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Home My WebLink AboutPLANNING 2019-02-28 COMPLETE AGENDA PACKETAllan Ekberg, Mayor Department of Community Development - Jack Pace, Director CHAIR, DENNIS MARTINEZ; VICE -CHAIR, HEIDI WATTERS; COMMISSIONERS, SHARON MANN, MIKE HANSEN, LOUISE STRANDER, KAREN SIMMONS AND DIXIE STARK PLANNING COMMISSION WORK SESSION February 28, 2019 - 6:30 PM TUKWILA CITY HALL COUNCIL CHAMBERS I. CALL TO ORDER II. ATTENDANCE III. ADOPT MINUTES IV. WORK SESSION ON CRITICAL AREAS REPORT V. ADJOURN Tukwila City Hall • 6200 authcenter Boulevard • Tukwila, WA 98188 • 206-433-1800 • Website: TukuvilaWA.gov 2 City of Tukwila BOARD OF ARCHITECTURAL REVIEW MINUTES Date: January 24, 2019 Time: 6:30 PM Location: Council Chambers Present: Chair Dennis Martinez, Vice -Chair Heidi Watters, Commissioners Sharon Mann, Mike Hansen, Louise Strander and Dixie Stark Absent: Commissioner Karen Simmons Staff: Planning Supervisor Minnie Dhaliwal, Senior Planner:Jaimie Reavis, and Planning Commission Secretary Wynetta Bivens Adopt Minutes: Commissioner Strander requested an amendment to the January 10, 2019 minutes. In the December 13, 2018 minutes the word "ritualization" should be revised to "re- channelization". Also, Commissioner Stark requested to amend the word "access" to "asset" on page 3. Commissioner Mann made a motion to adopt the January 10, 2019 minutes as amended. Commissioner Hansen seconded the motion. Motion passed. Commissioner Mann made a motion to adopt the October 25, 2018 Board of Architectural Review (BAR) minutes. Commissioner Hansen seconded the motion. Motion passed. Commissioner Hansen made a motion to adopt the October 25, 2018 Planning Commission (PC) work session minutes. Commissioner Watters seconded the motion. Motion passed, Chair Martinez opened the public hearing and swore in those wishing to provide testimony. CASE NUMBERS: L1S-0026 Design Review L18-0027 Conditional Use Permit (CUP) APPLICANT: Sean Hill of Broderick Architects on behalf of Vietnamese Martyrs Parish REQUEST: The applicant proposes a 7,000sf addition to an existing office building to create a learning center, partial demolition and construction of an addition to the main church building (67,500 sf), and related improvements including restriping and expanding the parking lot and landscaping. LOCATION: 6841 and 6847 S. 180th Street Minnie Dhaliwal, Planning Supervisor gave the presentation. She provided some background on the project. She said this item was before the BAR on October 25, 2018 and the hearing was continued to January 10, 2018 because the comment period for Department of Community Development (DCD) State Environmental Policy Act (SEPA) had not concluded. Therefore, no action could take place during the comment period. Additionally, the applicant submitted a letter at the hearing requesting 3 Page 2 of 5 January 24, 2019 BAR Minutes relief from the public access requirement, which was a Shoreline Master Program requirement. Staff worked with the applicant to find a mutually agreeable location for the public access, which was reviewed as part of the shoreline permit. The shoreline substantial development permit has been issued. Since the hearing was rescheduled to January 24, 2019 new public notice regarding the hearing date was provided, which included notice to the property owners within 500 feet of the property; posting the site; and publication in the newspaper. Staff asked the Commissioners the appearance of fairness questions. There were no disclosures, and no one objected to the Commissioners hearing the project. A walkthrough of the proposal was given, which is for a (CUP) and a design review application. CONDITIONAL USE PERMIT (CUP): There are three phases of the project. Staff recommended approval of the CUP with two conditions. Typically, CUP permits expire within a year. However, this is a phased project and the project requires a substantial shoreline development permit approval, which has a five-yearexpiration timeframe. Therefore, staff recommended the expiration of the CUP be consistent with the shoreline permit. Under the shoreline provisions the construction will start in two years and be completed in five years, with the possibility of a one-year extension that may be granted by the DCD Director. DESIGN REVIEW: Staff summarized the criteria of approval for the design review and recommended approval with two conditions. Staff answered questions from the Commissioner Sean Hill, Architect for the applicant, said the only change to the project since it was heard by the BAR in October was the public access they have been working on with staff. He asked for approval of the project. MOTION:..' Commissioner Hansen moved to approve with conditions case number L18-0026, Design Review based on the findings and conclusions contained in the staff reports dated January 15, 2019 and October 25, 2018 minutes. Commissioner Strander seconded the motion. Motion passed. Commissioner Hansen moved to approve with conditions case number L18-0027, CUP based on the findings and conclusions contained in the staff reports dated January 15, 2019 and October 25, 2018 minutes. Commissioner Strander seconded the motion. Motion passed. COMMENTS: Commissioner Watters said she is excited about the project, but she was disappointed that there wasn't specific plant species listed because it makes it hard to evaluate long-term value of the materials. She said, in the future, it would be better for it to be listed. Father Thanh Dao, the applicant, said they appreciate all the support for their church. He said they would like to work with the City and to make the city a better place. He also stated they will abide by the law. In conclusion he thanked the Commissioners. 4 Page 3 of 5 January 24, 2019 BAR Minutes CASE NUMBERS: APPLICANT: REQUEST: L18-0112 Variance L18-0065 Design Review Major Modification L08-079 Preliminary Subdivision Plat Mike Overbeck (1) Variance from side and rear yard setbacks, landscaping standards; and design review for construction of a third story on the building located at 14424 34th Ave S., and (2) Design Review Major Modification and Preliminary Subdivision Plat approval for phase 2 of the Osterly Park Townhomes. The 14424 34th Ave S. building will share recreation spaces and parking spaces within the Osterly Park Townhomes. Phase 2 of the Osterly Park Townhomes includes construction of 15 townhomes, guest parking, access, recreation space, and landscaping. LOCATION: 14426 34th Ave S., 14424 34th Ave S., and 14401-14420 34th Lane S., (Tax parcel numbers: 6433600090, 0040000083, 6433600110, 6391110000) 6433610240 Jaimie Reavis, Senior Planner, for DCD, gave the presentation. The preliminary subdivision plat and the design review applications were heard by the BAR on October 11, 2018. The October 11, 2018 hearing was continued because the BAR requested additional clarification and information be submitted. On December 13, 2018 the hearing was closed because the applicant added a variance application for approval for Lot 24 building. Information was given on the status of the construction and the phases of the project. Staff asked the BAR the appearance of fairness questions. Commissioners Hansen, Strander and Stark each disclosed they had exparte communication with the DCD staff about the project. No one objected to the Commissioners hearing the project. Staff provided background on the October 11, 2018 hearing. Staff said the applicant provided all items requested by the BAR and have also formed a Home Owners Association (HOA), which was formed with the owners of the Phase 1 property. An overview was given of the project for the variance, preliminary subdivision plat, and design review major modification. VARIANCE: The applicant requested a variance for setbacks and landscaping for the existing building located at 14424 34th Ave S. (Lot 24 of the proposed preliminary subdivision plat), which does not meet setback requirements along the west and north property lines. Also, it was noted that there is not enough space for required perimeter landscaping. Lot 24 will become part of the Osterly plat and will share landscaping. Staff recommended approval with three conditions as listed in the January 14, 2019 staff report. DESIGN REVIEW MAJOR MODIFICATION: An overview was given on the site plan, pedestrian and vehicular circulation, parking, and landscaping and building design. The applicant requested landscaping modifications to allow a perimeter sidewalk and to cluster required trees and shrubs. Staff recommended approval of the major modification to the design of the Osterly Park Townhomes with six conditions as listed in the January 14, 2019 staff report. Staff answered questions for the Commissioners. 5 Page 4 of 5 January 24, 2019 BAR Minutes PRELIMINARY SUBDIVISION PLAT: Staff said preliminary plat approvals are granted by the BAR for subdivisions of more than 10 lots or unit lots. The project initially received preliminary approval in 2008. The applicant is applying for new approval of a revised Phase II. The criteria address compliance with the City's Comprehensive Plan, appropriate infrastructure for the development, easements proposed for shared utility areas, lot design, compliance with subdivision and zoning regulations, maintenance, common infrastructure, recreation spaces and compliance with state law. Staff is recommending approval with 26 conditions as listed in the January 14, 2019 staff report. Mike Overbeck, applicant and developer, was present to answer questions. He said there were some minor changes to the recreation area. He talked about the challenges, many revisions and Jaimie Reavis' hard work. He said it has been a very trying project, but he has gotten lots of positive feedback regarding the project. Mr. Overbeck responded to questions and concerns from the Commissioners. Mr. Overbeck said some of the comments from the community were appalling. When asked about thenumber of conditions for approval for the preliminary plat hesaid he is not alarmed. Commissioner Watters inquired about the raised planters in the recreation space and suggested starter plants be put in the planters. The applicant said he could suggest it to the HOA that the planter be kept aesthetically pleasing. Commissioner Strander asked if the original homeowners had input in the plot design. Staff said a Notice of Application (NOA) and hearing was t recent NOA sent out done in October and again in December. There * d in response to the mos have also been conversations with the homeowners andmeetings with the HOA regarding the project. Staff said no public comments in December. There was no public testii The public hearing' DELIBERATION: Commissioner Hansen said he appreciated the amount of effort, time and years the applicant has spent to bring townhomes to Tukwila. He said itis not perfect but there is a lot to like about it, and he is supportive of keeping the project secure through fencing. He also said there were enough conditions that the project will be well monitored. Commissioner Mann said if this project is successful maybe there will be successive projects along the Tukwila Blvd. She also thanked staff and everyone else who have put patience and time into the project. Commissioner Martinez said our region is suffering from affordable housing and townhomes are helpful to young families starting out. He said staff done an excellent job on the presentation both last year and this year. Commissioner Stark said she feels very confident this will be a nice addition to Tukwila. 6 Page 5 of 5 January 24, 2019 BAR Minutes Commissioner Watters said she looks forward to seeing the improved entry level housing and diversification as well as activation of the community. The Commissioners were in consensus that the project will be a nice addition for the community. MOTIONS: Commissioner Hansen moved to approve with conditions case number L18-0112, Variance, based on the findings and conclusions contained in the staff report dated January 14, 2019. Commissioner Mann seconded the motion. Motion passed. Commissioner Hansen moved to approve with conditions case number L18-0065, Design Review Major Modification, based on the findings and conclusions contained in the staff report dated January 14, 2019. Commissioner Mann seconded the motion. Motion passed. Commissioner Hansen moved to approve with conditions case number L08-079, Preliminary Subdivision Plat, based on the findings and conclusions contained in the staff report dated January 14, 2019. Commissioner Mann seconded the motion. Motion passed. DIRECTOR'S REPORT: • An update was given of upcoming public hearings through May. Submitted by: Wynetta Bivens Planning Commission Secretary Adjourned: 8:10 PM 7 8 City of Tukwila Allan Ekberg, Mayor INFORMATIONAL MEMORANDUM TO: Planning Commission FROM: Minnie Dhaliwal, Planning Supervisor and Andrea Cummins, Urban Environmentalist DATE: February 19, 2019 SUBJECT: Update of TMC 18.45, Environmentally Sensitive Areas ISSUE Periodic update of the critical area regulations to reflect current best available science (BAS) as required by the Growth Management Act. BACKGROUND Staff had a work session with the Planning Commission on this item on November 8, 2019. The staff report for the November 8, 2018 meeting is available online. Here is the Il,iiin,k. At the Nov 8, 2018 meeting, the Planning Commission asked for some additional information on the following topics: 1. Mitigation plans and monitoring costs: At the last work session, the Planning Commission did not make a final decision on wetland buffers; and asked staff to provide examples of mitigation plans and associated monitoring costs. See Attachment A for a mitigation plan for buffer reduction of a stream. See Attachment B for a mitigation plan for filling some wetlands and doing offsite mitigation. Also, included in these attachments is the cost estimate for the mitigation and monitoring. The Department of Ecology recommends the buffers listed in table below. It should be noted that the buffer widths shown in the table below assume that the buffer is vegetated with native plants and minimization measures listed in the second table are implemented. If the buffer is unvegetated, sparsely vegetated, or vegetated with invasive species, the buffer would need to be re -planted or the buffer width increased to provide adequate buffer functions. 9 INFORMATIONAL MEMO February 19, 2019 Page 2 Category Wetland buffer width (ft), current TMC Wetland buffer width (ft), Ecology 2014, high -intensity land use impact Habitat score <6 Habitat score <6 Habitat score 6-7 Habitat score 6-7 Habitat score 8- 9 Habitat score 8-9 Standard Buffer Alternate Buffer if impact minimization measures taken Standard Buffer Alternate Buffer if impact minimization measures taken, plus 100 feet vegetated corridor between wetland and priority habitats Standard Buffer Alternate Buffer if impact minimization measures taken, plus 100 feet vegetated corridor between wetland and priority habitats I 100 100 75 150 110 300 225 II 100 100 75 150 110 300 225 III 80 80 60 150 110 300 225 IV 60 50 40 50 40 50 40 Listed below are the impact minimization measures that may allow 25 percent reduction from the upper range of recommended buffers: Disturbance Required Measures to Minimize Impacts Lights • Direct lights away from wetland Noise • Locate activity that generates noise away from wetland • If warranted, enhance existing buffer with native vegetation plantings adjacent to noise source • For activities that generate relatively continuous, potentially disruptive noise, such as certain heavy industry or mining, establish an additional 10' heavily vegetated buffer strip immediately adjacent to the outer wetland buffer Toxic runoff • Route all new, untreated runoff away from wetland while ensuring wetland is not dewatered • Establish covenants limiting use of pesticides within 150 feet of wetland • Apply integrated pest management 10 INFORMATIONAL MEMO February 19, 2019 Page 3 Disturbance Required Measures to Minimize Impacts Stormwater runoff • Retrofit stormwater detention and treatment for roads and existing adjacent development • Prevent channelized flow from lawns that directly enters the buffer • Use Low Intensity Development (LID) techniques where appropriate (for more information refer to the drainage ordinance and manual) Change in water regime • Infiltrate or treat, detain, and disperse into buffer new runoff from impervious surfaces and new lawns Pets and disturbance human • Use privacy fencing OR plant dense vegetation to delineate buffer edge and to discourage disturbance using vegetation appropriate for the ecoregion • Place wetland and its buffer in a separate tract or protect with a conservation easement Dust • Use best management practices to control dust Based on the field work done to categorize the wetlands north of 1-405, majority of the wetlands are Category III wetlands, with a low habitat score of 3-5. Buffer quality at the vast majority of wetlands is unhealthy (too narrow, dominated by invasive species, or sparsely vegetated.) Initial comparison of buffers required under the existing code and buffers recommended by the Department of Ecology indicates that buffers will increase for some wetlands while a few wetlands may see reduction in the required buffer width. Policy Options for buffer widths: Pros Cons Option 1 Adopt the standard buffer widths The larger buffers Buffer widths will recommended by the Department will provide better significantly increase of Ecology buffer function given majority of the buffers are sparsely vegetated; easier for the developer as no replanting or monitoring required which could limit development potential; quality of buffers will not improve as no replanting required. Option 2 Adopt the standard buffer widths Provides options for Quality of buffers will not recommended by the Department of Ecology; but allow alternate buffer if impact minimization measures are taken. This option assumes that the existing buffer is vegetated with native plants. It should be noted that most existing buffers are not vegetated with native plants, therefore standard buffer widths would apply under this option. the developer improve as no replanting required. Also, since the state of existing buffers is degraded, it is likely that under this option standard buffers will apply so this option will likely be similar to Option 1 during implementation. 11 INFORMATIONAL MEMO February 19, 2019 Page 4 Option 3 Adopt the standard buffer widths Provides options for Requires monitoring of recommended by the Department the developer with the replanted buffer for of Ecology; but allow alternate buffer if impact minimization measures are taken AND buffer is replanted incentives for buffer enhancement at least five years At the November 8, 2018 meeting the Planning Commission did not make a final decision on this item. Staff recommends Option 3. 2. Exempt wetlands: The existing code provides an exemption for certain wetlands that are under 1,000 square feet. The exemption is from sequencing (showing that the impact cannot be avoided or minimized). Mitigation of the impacts is still required per Ecology. Exempt wetlands have to meet the following criteria: a) habitat score under five; b) are not associated with a riparian habitat or Shorelines of the State; c) are not part of a wetland mosaic, and d) do not contain priority habitat. Per Ecology guidance, this exemption may be extended to isolated Category IV wetlands under 4,000 square feet. Here are policy options that the Planning Commission considered at the November 8, 2018 meeting: Pros Cons Option 1 Keep the existing code and exempt wetlands up to 1000 sq. ft with mitigation for wetland impacts These are exempt under the existing code. Code language could be clarified that wetland impacts still need to be mitigated. Some larger wetlands that could qualify for exemption would not qualify. Option 2 Exempt wetlands up to 4000 sq. ft. with mitigation for wetland impacts Increase the exemption to the highest allowed under BAS. Wetland impacts are mitigated Mitigation is off site or by fee in lieu. Loss of wetlands in Tukwila. Buffer impacts are not mitigated. Option 3 Exempt wetlands up to 1000 sq. ft. with mitigation for wetland impacts; exempt wetlands up to 4000 sq. ft. with mitigation for wetland and buffer impacts Increase the exemption to the highest allowed under BAS. Two tiers of mitigation: wetland and buffer impacts are mitigated for wetlands larger than 1000; and only wetland impacts mitigated for wetlands smaller than 1000 sq. ft. Mitigation is off site or by fee in lieu. Loss of wetlands in Tukwila. 12 INFORMATIONAL MEMO February 19, 2019 Page 5 At the November 8 work session, the Planning Commission recommended Option 3, but asked staff to do some additional research and provide data on how many wetlands would be impacted under Option 3. See Attachment C for the map of known wetlands in Tukwila that are less than 1000 square feet; and those that are between 1000 to 4000 sq. ft. Here is the data: 1,000 square feet or less: 5 wetlands 1,001-4,000 square feet: 17 wetlands; all are part of a mosaic except for 4 of them. It should be noted that 13 out of 17 wetlands that are between 1,001 to 4,000 square feet in size would not qualify for the exemption as they are part of a wetland mosaic. Based on this additional research staff recommends Option 1. 3. Non -conforming provisions: At the last work session, the Planning Commission asked staff to do additional research to establish new non -conforming thresholds for development in the wetland and stream buffers; and tie the new thresholds to incentives for improving the buffer and/or water quality. Tukwila Municipal Code 18.70.040 and .050 addresses code provisions for any non- conforming uses or structures in Tukwila. See Attachment D for Tukwila's code. See Attachment E for comparison of non -conforming provisions of other cities. Attachment F is an excerpt from Kirkland's code that has very specific guidelines for expansion of non- conforming structures in the critical area buffers. The policy options for the Planning Commission to consider are: A. Vertical Expansion Pro Con Option 1 Allow existing buildings Allow Reduces to expand vertically to improvements future potential add upper stories in to existing of the non - exchange for buffer buildings and conforming enhancement achieve buffer enhancement structure to come into compliance Option 2 Do not allow vertical Preserves Restricts expansion potential for non- conforming structure to come into compliance with critical areas code in the future. development potential. Missed opportunity for buffer enhancement 13 INFORMATIONAL MEMO February 19, 2019 Page 6 B. Lateral Expansion Pro Con i) Expansion to the building side that is opposite of critical area Option 1 Allow expansion on side of the building opposite of critical area in exchange for buffer enhancement; but limit it to one time expansion Allow improvements to existing buildings and achieve buffer enhancement Reduces future potential of the non - conforming structure to come into compliance. Harder to administer Option 2 Do not allow expansion in the buffer Preserves potential for non- conforming structure to come into compliance with critical areas code in the future. Easy to administer Restricts development potential. Missed opportunity for buffer enhancement Staff recommends Option 1 ii) Expansion along the sides provided that existing distance from the structure to the buffer's edge is not reduced. Option 1 Allow expansion along the existing building lines in exchange for buffer enhancement; but limit it to one time expansion and limit the sq. ft. of new intrusion into the buffer to less than 50 percent of the current intrusion. Further this option could be limited to situation where the buffer width is at least 75 percent of the required buffer Allow improvements to existing buildings and achieve buffer enhancement Reduces future potential of the non - conforming structure to come into compliance. Harder to administer 14 INFORMATIONAL MEMO February 19, 2019 Page 7 Option 2 Do not allow expansion in the buffer Preserves potential for non- conforming structure to come into compliance with critical areas code in the future. Easy to administer Restricts development potential. Missed opportunity for buffer enhancement Staff recommends Option 1 iii) Enclosing within existing footprint (such as enclosing carport, adding roof over decks) Option 1 Allow enclosing within existing footprint Less restrictive. No additional impact to the buffer. Option 2 Do not allow enclosing within existing footprint Restricts development potential without much gain to the critical areas. Staff recommends Option 1 4. Geologically Hazardous Areas Planning Commission had asked if there could be a minimum setback established from a steep slope in lieu of preparing a geotechnical report for the property. This section of the code is administered by the City's Public Works Department and their opinion is not to establish one standard setback for all slopes. Instead the setback should be established by the geotechnical engineer after evaluating site conditions for each site. RECOMMENDATION Consider policy options identified above and identify any additional research needed. Staff will then prepare an underline strike out of the code that addresses the gaps identified by the review of best available science. The Planning Commission will then hold a public hearing and send a recommended draft to the City Council for review and adoption. ATTACHMENTS A. Stream buffer monitoring report B. Wetland monitoring report 15 INFORMATIONAL MEMO February 19, 2019 Page 8 C. Map of known wetlands in Tukwila that are less than 4000 sq ft. D. Tukwila's non -conforming code provisions E. Comparison of non -conforming provisions of other cities. F. Kirkland's non -conforming code provisions 16 J. S. Jones and Associates, Inc. Type 4 Watercourse Buffer Enhancement Plan and Justification for Buffer Reduction of the 15404 40th Avenue South Property King County Tax ID No.: 004300-0266 Prepared for: FLS Development, LLC 155 SW 152nd Street, #A Seattle, Washington 98166 206-423-8425 Dated: May 14, 2010 Prepared by: Lance Erickson, Environmental Designer rimer 0 AUG 12 20 I o p vuo, 402 EAST MAIN STREET, SUITE 110 AUBURN, WASH 1 N G T O N 9 8 0 0 2 253-804-2645 / FAX 253-333-8584 17 Executive Summary The subject property is located at 15404 40th Avenue South, in Tukwila, Washington. A Type 4 watercourse is located between the north property line and South 154th Street. Type 4 watercourses are required to have a 50-foot buffer in the City of Tukwila. The applicant proposes to reduce the buffer by 50% and enhance the remaining buffer area. No evidence of additional sensitive areas are present south of the Type 4 watercourse. The remainder of the property is dominated by invasive vegetation which include Himalayan blackberry and non-native grasses. The applicant proposes to remove the invasive vegetation within the proposed enhancement area and install native trees and shrubs. The total area of enhancement is 3,057 square feet. The enhancement area will be planted with plant materials native to the Puget Sound lowlands. Native plant species will increase plant diversity, wildlife habitat and prevent the establishment of invasive species. In addition to the proposed enhancement, the reduced buffer will be fenced with split rail fencing and stream buffer signs will be posted. Detailed plans documenting the proposed enhancement are shown on the attached mitigation plan. Figure 1.0 Proposed buffer reduction and enhancement area (existing lawn located in the northwest corner of the subject property) Baseline Information The subject property is located at 15404 40th Avenue South, in Tukwila, Washington. The tax parcel number is 00430-0266. The property is located in the southwest quarter of Section 22, Township 23, Range 04 East of the Willamette Meridian. A watercourse flows from a culvert under 40th Avenue South and runs parallel to the north property line. The watercourse is located in the vacated Right of Way for South 154th Street. The stream is rated as a Type 4 Watercourse. Section 18.45.100.A.4 of the Tukwila Municipal Code (TMC) defines Type 4 Watercourses as "those watercourses that have intermittent flows and are not used by salmonid fish." Type 4 Watercourses are required to have a 50-foot wide buffer. No evidence of additional sensitive areas are present south of the Type 4 watercourse. The remainder of the property is dominated invasive vegetation which include Himalayan blackberry and non-native grasses. Most of the eastern portion of the property is being used as residential lawn. The property slopes approximately 5% to the east. A residence and four associated out buildings (a detached garage and three sheds) are present. Multi -family residences are present to the south and east. May 2010 2 J. S. Jones and Associates, Inc. 18 Figure 2.0 Type 4 Watercourse (view from side walk at northeast corner of property) The TMC allows for buffer width variations. Section 18.45.10.F.1 of the TMC states "The Director may reduce the standard watercourse buffers on a case -by -case basis, provided the buffer does not contain slopes 15% or greater. The approved buffer width shall not result in greater than a 50% reduction in width. Any buffer reduction proposal must demonstrate to the satisfaction of the Director that it will not result in direct, indirect or long-term adverse impacts to watercourses." The applicable sections of the TMC are attached. Justification for Buffer Reduction This action is permitted in the TMC in Section 18.45.100.F.la which states: "The Director may reduce the standard watercourse buffer on a case -by -case basis, provided the buffer does not contain slopes 15% or greater. The approved buffer width shall not result in greater than a 50% reduction in width. Any buffer reduction proposal must demonstrate to the satisfaction of the Director that it will not result in direct, indirect or long-term adverse impacts to watercourses, and that b), if there is no significant vegetation in the buffer, a buffer may be reduced only if an enhancement plan is provided. The plan must include using a variety of native vegetation that improves the functional attributes of the buffer and provides additional protection for the watercourses functions and values." The proposed buffer reduction meets the required conditions as follows: • The buffer is less than 15% slope • The proposed reduction is not greater than 50% • The existing buffer is mowed and maintained lawn, invasive Himalayan blackberry, and un- maintained grasses. In is current state the buffer provides little to no function or values to the Type 4 Watercourse. Enhancement will increase the functions and values of the buffer. • Enhancement with native trees and shrubs will increase both the function and the value of the buffer area. Native trees and shrubs will increase will increase plant diversity, wildlife habitat and prevent the establishment of invasive species. May2010 3 J. S. Jones and Associates, Inc.. 19 Environmental Goals and Objectives The goal of mitigation is to increase the functions and values of the existing Type 4 Watercourse buffer through enhancement. The area of stream buffer which is proposed to be reduced is currently maintained lawn, invasive Himalayan blackberry, un-maintained grasses and weeds. Enhancement will provide a greater functions and values by improving plant diversity, wildlife habitat, and protection for the off -site watercourse. The objectives necessary to meet the above stated goal area as follows: • Remove invasive vegetation from the stream buffer • Remove trash and debris from the stream buffer • Install native vegetation within the stream buffer • Install split rail fencing and stream buffer signs at the limits of the proposed buffer deter future intrusions into the sensitive area • Maintain and monitor the enhancement area for a period of three years or until the site meets the specified performance standards • Record the sensitive area in a "Notice on Title" • If the enhancement area fails to meet performance standards provide a contingency plan to rectify the situation. Buffer Reduction and Mitigation The area of the existing 50-foot buffer is 8,009 square feet. The applicant proposes a 50% reduction for enhancement. The remaining buffer area to be enhanced is 3,057 square feet. Section 18.45.10.F.1.B of the TMC, allows for reduction of a watercourse buffer by up to 50% if there is no significant vegetation present and an enhancement plan is provided. The western portion of the on -site buffer area is dominated by mowed and maintained lawn. The eastern portion is dominated by invasive Himalayan blackberry and un-maintained grass and weeds (see Figure 1.0 and Figure 3.0). The applicant proposes to remove the weeds and invasive vegetation and replant the area with native trees and shrubs. Native plant species will increase plant diversity, wildlife habitat and prevent the further establishment of invasive species. One existing maple tree will remain in the buffer area. No impacts to the Type 4 watercourse are proposed. Plant quantities were calculated on a 9'x 9' spacing for trees and 5'x 5'spacing for shrubs. 40 trees and 120 shrubs are proposed for installation within the enhancement area. The enhanced buffer will be fenced with split rail fencing. Two stream buffer signs will be posted on the split rail fence. Details for split rail fencing and stream buffer signs are shown on the attached planting plans. May 2010 4 J. S. Jones and Associates, Inc. 20 Figure 3.0 Invasive plant material and existing landscape trees in the mitigation area. Performance Standards The plant survival and cover standards established to measure the success of the mitigation area are as follows: Year 1 Year 2 Year 3 Shrub and Sapling Tree Cover* >10% >15% >20% Shrub and Sapling Tree Survival 100% >85% >80% *Includes beneficial native plants in that category that are naturally recruiting volunteers • Less than 10% invasive vegetation during any monitoring event. • The establishment of 3 species of native trees and 4 species of native shrubs at the end the monitoring period. Monitoring Program The applicant's environmental consultant will perform a three-year monitoring program. A monitoring report will be submitted to the City of Tukwila by December 31 st of each year beginning the first fall after enhancement installation. Sample points or transects will be established for vegetation monitoring. Photo -points will be established from which photos will be taken throughout the monitoring period. Linear transects are the preferred method for vegetation monitoring for this site. No less than one (1) 50 foot transect will be established in the mitigation area. Permanent transect location(s) must be identified on the approved mitigation plans in the first monitoring report (they may be drawn on approved mitigation plans by hand). Plots located at the end of each transect shall detail herb, shrub, and tree aerial cover at radii of 1m, 5m, and 10m respectively, using the Braun-Blanquet releve method or other acceptable field method. Monitoring of vegetation transects shall occur annually between August 1 and September 30, prior to leaf drop, unless otherwise specified. May 2010 5 J S. Jones and Associates. Inc. 21 As applicable, the monitoring reports must include description/data for: • Project reference number • Site plan and location map • Historic description of the project, including date of installation, current year of monitoring, restatement of enhancement goals, and performance standards • Plant survival, vigor, and aerial coverage from every plant community and an explanation of monitoring methodology in the context of assessing performance standards • Hydrologic data from wells, hand -ball test, and visual observations, and an explanation of monitoring methodology • Buffer conditions, e.g. surrounding land use, use by humans, wild and domestic creatures • Observed wildlife, including amphibians, avians and others • Assessment of nuisance/exotic biota and recommendations for management • Receipts for off -site disposal of any dumping, weeds or invasive plants • Receipts for structural repairs or replacement • Color photographs taken from permanent photo -points as shown on enhancement plan • Summary of maintenance and contingency measures proposed for next season and completed last season Maintenance Plan In order to achieve performance standards, the applicant shall have the mitigation area maintained for the duration of the monitoring period. Maintenance shall be required in accordance with City of Tukwila guidelines and approved plans. Maintenance activities will be conducted a minimum of twice per year (April and September) for the duration of the monitoring period, three years. Maintenance will include: • Watering • Weeding around base of installed plants • pruning • Replacement • Restaking • Removal of all classes of noxious weeds (see Washington State Noxious Weeds List, WAC 16- 7150-005) as well as Himalayan blackberry • Any other measures needed to insure plant survival • General maintenance activities which include the replacement of any vandalized or damaged signs, habitat features, fences or other structural component of the mitigation site. Chemical controls shall not be used in the mitigation area. However, limited use of herbicides may be approved depending on site specific conditions, only if approved by City of Tukwila staff. All invasive material and debris is to be disposed of off -site in a legal manner. The Permittee shall be responsible for the health of 100% of all newly installed plants for one growing season after installation has been accepted by City of Tukwila staff. A growing season for these purposes is defined as occurring from spring to spring (March 15 to March 15, following year). The Permittee shall replace any plants that are failing, weak, defective in a manner of growth, or dead during this growing season, as directed by the Landscape Designer, Wetland Biologist, and/or City of Tukwila staff. Water shall be provided during the dry season (July 1-October 15) for the first two years after installation to ensure plant survival and establishment. Water should be provided by a temporary above ground irrigation system. Water should be applied at a rate of 1" of water two times a week for Year I and 1" of water one time a week during Year 2. May 2010 6 J S. Jones and Associates, Inc. 22 Contingency Plan Should any monitoring report reveal the enhancement has failed in whole or in part, and should that failure be beyond the scope of routine maintenance, a contingency plan will be submitted. Once approved, it may be installed, and will replace the approved enhancement plan. If failure is substantial, the City of Tukwila may extend the monitoring period for the enhancement. Performance Bonds Prior to beginning any work, the Permittee must provide a mitigation bond or assignment of funds per City of Tukwila procedures. A bond quantity worksheet has been completed based on all elements of the mitigation plan. The total cost, plus contingency fees has been determined to be $ 13,894.37 , which will be the amount of the mitigation bond the Permittee is required to provide. Critical Areas Mitigation Bond Quantity Worksheet Project Name: Tukwila Property Date: 5/14/10 Prepared by: J. S. Jones and Associates, Inc. Location: 15404 40th Avenue South Applicant: FLS Development, LLC Phone: 206.423.8425 PLANT MATERIALS' Type Unit Price 1 Uni Quantity Descrt ion Cost PLANTS: Container, 1 gallon, medium sod I 311.50 Each 105 a .,. $ 1.207.50 PLANTS: Container, 29alIon, medium soil I 320.00 Each 15 S 300.00 3 1,440.00 PLANTS Container, 5 gallon, medium and I 338.001 Each) 40 • M cods intlude nweadan ITOTA! $ 2,947.50 INSTALLATION COSTS ( LABOR, EQUIPMENT, 8. OVERHEAD) Type Und Price Until 1, ... ............... general ) 340.001 24 I 980.00 Hauling and disposal : 34001 Cyr 4 Mulch, delivered and spread 335.7 CY 5 S 200.00 5.... 178.65 __.. ..... TOTAL S 1,338.65 GENERAL ITEMS ITEMS Unit Cost Uni Cost II Fencnsplit rail. 3' high (2.ratt ..... 310.54 L 185 ,.,. S 1.949.90 Sins sensible area boundary(inc. hacking, post install) 328.5 Each 2 TOTAL $ ...... 57.00 S 2,006.90 OTHER '', (Construction Cost Subtotal) S 8,293.05 ITEMS Percentage of I Construction Unit Cost Modgzabon 10%�.�.$ 829.31 CantingencY.._ ...... I .. 30% (TOTAL $ 1,887.92 5.... 2,517.22.. NOTE: Projects with multiple permit requirements may be required to have longer MAINTENANCE AND MONITORING monitoring and maintenance terms. This will be evaluated on a case -by -case basis for development applications. Monitonng and mainframe ranges may be 'I. assessed anywhere from Maintenance, Twice Annual n.,.,..,..�.._..._... I. Larger than 1,000 sq. fL but less than 5.000 sea. d buffer mitigation $ 180.00 EACH 9I4hr/0345/hr) I S 1,620.00 Morilaurg, annuat Larger than 1,000 sq.ft but less than 5,000 -buffer mitigation on .... $ 720.00 EACH( 3I(8 hrs gi 90/hrl S 2,180.00 Maintenance and Moniloring Inspection (City). annual 3382.25 EACHI 2 (2.5 hrs 5144.90/hr) S 724.50 Maintenance and Monitoring Inspection (City), final 3579.80 EACHI 1 (4 hrs 0 $144.901hr) I S 579.60 r _.. 'TOTAL ', $ 5,084.10 '.. Total $13,894.37 May 20/0 7 J. S. Jones and Associates. Inc. 23 24 I!%J\ IrMtr'J L IILl IV1.1.. UU'1,7UU-EJ OO 30 TREE AND SHRUB PLANTING AND:STAKING DETAIL ROOTENN NA-TERS. � ® z- —.z. �. rb :�a.�. NATIVES.. 7 / 7 #iL 1 — — AL15U I5. 3' � 1 SILT E 4 E E Teaizma r lALOY amBML+ Fa ErA... MOWN 8011.01A0 SE c-sue '1 ......100NRATELT SWARD A ROOT maxMraALA. i`oiss PLONTINGNOLE :-\LLrO ti f I ALO0 ALO f, O STRUC 10I I�BARRI R FENCE — TYPE 4 WATERCOURSE 20367 / `— SPLIT RAIL co —/— co I Lo N III ICE DETAILS aEGEWITN aONCENTER GE Imo' 7. III=Y N'STREAM BUFFER SIGN / 2' REDUCED BUFFER i / 25�-��\T I REMOVED VsACT 54TH i 9R E lR0I S OI571-7 SILT FENCE DETAILS EQUIRED BUFFER 1 1-�p4300 6p II N , 1 \ �,r= SYMBOL CQNMON.Nis PLANT SCHEDULE -SCIENTIFICNAME 510 BIG-LEAFiMAPLE .ACER MACROPHYLLUM 20 RED ALDER ,ALNUSRUBRA 20 DOUGLAS FIR IPSEUDOTSUGA MENZIESII 15 MINE MARLE ACER CIRCINATUM 20 RED -FLOWERING CURRANT ,RISES SANGUINEUM 40 NOOTKA ROSE -ROSA NUTKANA 30 SALMONBERRY RUBUS SPECTABILIS 40 SNOWSERRY 'SYMPHORICARPOS ALBUS 45 INVASIVE REMOVAL NOTES: NON NATIVE INVASIVE PLANT' MATERIAL SHALL BE GRUBBED OUT OF THE MITIGATION METHODS1(I.E EXCAVATOR OR BACKHOE). CONSULTING BIOLOGIST SHALL BE PRESET INVASIVE REMOVAL TOiSUPERVISE CLEARING ACTIVITIES. ORANGE CONSTRUCTION E SHALL BE INSTALLED AT THE DRIPLINE OF THE LARGE DOUGLAS FIR TREE TO MINIMIZ ROOT SYSTEM (SEE DETAIL). 'ALL INVASIVE REMOVALWITHIN THE DRIPLINE OF NATIVI REMAIN WILL BE DONE BY. HAND. 2-4 L'1� r!GG FUEL OR MEDIUM BARKTi JLT SHALL dB. CR MEDIUM BARK MULCH YNLL NFFLP ER-MTAIR SPLIT RAIL FENCE DETAI STREAM. SIGN DETAIL (TYPICAL) ATTACH Ole GALVANIZED UG 9 WITS WASHERS L, SIG N TAIL THE BOUNDARY ABBSIGN ETWEEN NrESE.E°� AREA. SETBACK TRACT AND T„EBU o GS...1R. TO GRADE PRENRI RUSTIC A Type 4 Ddfer kW. pan theP ham trent Proposea In with naive um and ersity, we habitat ark on within the proposed s. The total area of proposed enhancement, :Mg and stream buffer nd values of the existing 'he area of stream buffer ad omimental rotection for the off -site above stated goal area as offer er s at the limits of the sensitive area r a period of five years or ;tandards race standards provide a u, in Tukwila, :wile standards and shown on these plans. an impute trapethion ur gectitnitval shall be -Cemmunity rovided to the City of lumbers of persons/firms estomtion area, installing ice and monitoring. f m mitigation and there is one person on the thoroughly familiar with sthods for their formed under these installing native plant sets, unless otherwise gist and/or City of :ape Designer and/or :ely to be deterimental to as depicted in the Wetland Biologist may iced on field conditions. ie following conditions: ively wet weather, hanges should be City of Tukwila upon 9.2 Plant Names: Plant names shall comply with those generally accepted in the native plant nursery trade. Any questions regarding plant species or variety shall be referred to the Landscape Designer, Wetland Biologist or City of Tukwila staff All plant materials shall be true to species and variety. 9.3 Plant Substitutions: Plant substitutions are not permitted without the Mitre L am. Destg_avr, 2§..elmxl _ roe midlth City of Tukwila ila staff Saute ciao. roloarbinchs of tram suedo oth riNithe bra: palmt of i5 eenr null pots ohm wi ltiaa lays traspilma shed and adavt more quickly to site sondirons, resultng in a him =tress raat€. As sarit vrtallet Maori will be thrompand: s mitratitinom bad certain sits- ifs; QmrLitimo (M5 Mt IfISS elan I grit siZt e'er).. 9.4 QuaTiM and Condrtrent Plants shall be ton -smut in petherecrtionialt health, warbrorthcit vigorc.s, with well-dovemtol Mead yST,MT, th-th ?lire of perms aeon Amami. Damaged, dimmed, piton , lionsedi th-ioduitt, burned, ed, Prrokrat iv defective pfaas will be rajwithi 93 lottralediattakpadimv All plantsshall he 'ed byig.L 000ipnDtssgsm anthorWad.:atara-to thitafiethian CBEs of rthasuia:ankdc sample Mks will be 'be irapethadievelm. aL above:= moods en all piano ROOtS of any been root plaraa, if parmstt: d fi.€ i wall Y 3- Plant material. may bo apX,31-T4 of sow at the di,c-rction of the r 'urW iPsetoggs4 r but all erut in.=. insist be re -inspected mid�eed. tm the siem-am- to installation. 9.6 Handling: Plants shall be handled so as to avoid all damage, including breaking, bruising, root damage, sunburn, drying, freezing or other injury. Plants must be covered during transport. Plants shall not be bound with wire or rope in a manner that could damage branches. Protect plant roots with shade and wet soil in the time period between delivery and installation. Do not lift container stock by trunks, stems, or tops. Do not remove from containers until ready to plant. Water all plants as necessary to keep moisture levels appropriate to the species horticultural requirements. Plants shall not be allowed to dry out. All plants shall be watered thoroughly immediately upon installation. Soak all containerized plants thoroughly prior to installation. Bare root plants are subject to the following special requirements, and shall not be thed halms between Davin I and March 1, and only with the permiethim of the Landscape t1 and City of Tukwila staff. Bare root p enss omit ham math* fibuto miens to Menu plant survival) Roots must be covered at all times with mud and/or wet straw, moss, or other suitable packing material until time of installation. Plants whose roots have dried out from exposure will not be accepted at usulailrrtion inspettim Plan - ed. dried othior otim€wi.__.m dl Piatdn cs-iitt he reacted at irsiallutien inspection All oetnc.. d planM 498 he thiradiamity removed from the kin 9,8 Realm ARM -arils shall be bailed andbur7agiped ur coresiineerzart. urn explthity aeeiiirieml by the Lasdscapo Piithimer thiathor Wetland Biologist Roth. booth mitts or B plants cormdamsgol, ermthed m tons fmu30 lei will to red intriediatelybefa' on, plants w muter root damage Nam breken ondlor [wig`) m,in bo reithismithext Matted or cashes roots of trodamenied plitaings intrat M. mimed aightnsnd and the skim of the riot hall most be rampiamed Theo tem to lesions ra n doh of ntimoseuntely half and atth in two to font toot pings of woody material is allowed . only with pianteishim fuses ttu lam: pe Demeter. Watimith Doiugist, orellor City M Tarim& 9.9 Slams Plant vices shall be the size indseated is the plant atheichile Larger stock may be acceptable provided that it has not been cut back to size specified, and that the root ball is proportionate to the size of the plant. Smaller stock may be acceptable, and under some circumstances perferable, based on site -specific conditions. Measurements, caliper, branching and balling and burlapping shall conform to the American Standard of Nursery Stock by the American Assoiciation of Nurserymen (latest edition). 9.10 Form: Evergreen trees, if used, shall have single trunks and symmetrical, well -developed form. Deciduous trees shall be single [ranked unless specified as multi -stem in the plant schedule. Shrubs shall have multiple stems, and be well -branched. 9.11 Planting: Planting shall be done in accordance with illustrated details in the mitigation/restoration plan set and accepted industry standards. Plant locations shall also be inspected and approved prior to planting. 9.12 Timing of Planting: Unless otherwise approved by City of Tukwila staff, all planting shall occur between September 1 and March 31 9.13 Planting in Pits: Planting pits shall be circular or square with vertical sides, and shall be 6" larger in diameter than the root ball of the plant. Break up the sides of the pit in compacted sods. Set plants upright in pits, as illustrated in planting detail. Burlap shall be removed from the planting pit Backfill shall be worked back into ]roles such that are pockets are removed without adversely compacting soils. 9.14 Soil Amendments: Unless otherwise specified and approved by City of Tukwila, native soil will be incorporated into the planting pits. 9.15 Mulch: The entire mitgation area shall receive no less than 2"-4" of hog fuel or medium bark mulch after planting. Hog fuel or mulch shall be kept well away (at least 2") from the trunks and stems of woody plants. 9.16 Fertilizer: Slow release fertilizer may be used if pre -approved by City of Tukwila staff. Fertilizers shall be applied only at the base of plantings underneath the required covering of mulch (that does not make contact with stems of the plants). No fertilizers will be placed in planting holes. 9.17 Water: Plants shall be watered upon completion of backfilling. For spring plantings (if approved), a rim of earth shall be mounded around the base of the tree or shrub no closer than the drip line, or no less than 30" in diameter, except on steep slopes or in hollows. Plants shall be watered a second time within 24-48 hours after installation. The earthen rim/dam should be leveled pnor to the second growing season. 9.18 Staking: Most shrubs and many trees do not require any staking. If the plant can stand alone without staking in a moderate wind, do not use a stake. If the plant needs support, then strapping or webbing should be used as low as possible on the trunk to 1`oosely brace the tree with one stake (see Planting Detail). Do not brace the tree tightly or too high on the trunk. If the tree is unable to sway, it will further lose the ability to support itself As soon as supporting the plant becomes unnecessary, remove the stakes. All stakes must be removed within two (2) years of installation. 9.19 Weeding: Existing and exotic vegetation in the mitigation and buffer areas will be hand weeded from around all newly installed plants at the time of installation and on routine basis through monitoring period. No chemical control of vegetation on any portion of the site is allowed without the written permission of City of Tukwila staff. 10.0 Maintenance Maintenance shall be required in accordance with City of Tukwila guidelines and approved plans. 10.1 Duration and Extent: In order to achieve performance standards, the Permittee shall have the mitigation/restoration area maintained for the duration of the monitoring 3 man. Al matitsith shall be directed by the Landscape Onsigradthalleir Wetim d Its, Maintenance will include: • watering (see. 1O, 7 for details) • weeding around base of installed plants • pruning • replacement (see 10.5 for details) • restaking • removal of all classes of noxious weeds (see Washington State Noxious Weeds List, WAC 16-7150-005) as well as Himalayan blackberry • any other measures needed to insure plant survival (see 10.6 for details) • general maintenance activities which include the replacement of any vandalized or damaged signs, habitat features, fences or other structural component of the mitigation site. 10.2 Survival: The Permittee shall be responsible for the health of 100% of all newly installed plants for one growing season after installation has been accepted by City of Tukwila staff (see Performance Standards). A growing season for these purposes is defined as occurring from spring to spring (March 15 to March 15, following year). For fall installation (often required), the growing season will begin the followingspring. The Pemsittee shall replace any plants that are failing, weak, defective in a manner of gui.wai, or thud dies this - _ es dime -Mel by the TM Lthiseute Thisignia Wetland Biologist,sir =cr City of Tukwila staff 103 tiatithatderi Timing far Raplasetheaffinetio rla tmii sins Abel be walled bra_ Seth-MutesSeth-Mutes I and March 31, *less otherwise i dmainaned by theLandscape Designer,WadandiBiol. math City of Tukwila staff. 10.4 Standards for Replacement Plants: Replacement plants shall meet the same standards for size and type as those specified for original tosiothithei ran. i ativss - d by the Lanbtpt Deirigram Walawd Bielogitat. anther City of Tukv da ear ma 3 Nam anal Ce inspected. ta described abovefor the or€grnal trimatliatian 195 Replanting: Plano s at smiledts theirplatingtop deeptw sltalluw, l e, toemptred Mall be nignanted as thommil by the Landieme Desionth, Wetland Biclo$lat, thithor City off:=s i4d5 Pfartielem/Pealealem C'hr ucal cdaaob thell on he used rn mitigationhestoration area, sensitive areas or their buffers. However, limited use of herbicides may be approved depending on site specific conditions, only if approved by City of Tukwila staff. 10.7 Irrigation/Watering: Water shall be provided during the dry season (July 1-October 15) for the first two years after installation to ensure plant survival and establishment Water should be provided by a temporary above ground irrigation system. It is the responsibility of the applicant to have the temporary irrigation designed, installed and maintained so that the necessary water amounts are provided. Water should be applied at a rate of I" of water two times a week for Year 1 and I" of water one time a week during Year 2, 11.0 Performance Standards - Plant Cover and Survival • Plant survival and cover standards are established -to measure mitigation success as follows: Year 1 Year2 Year3 Shrub and Sapling Tree Cover* >10% >15% >20% Shrub and Sapling Tree Survival 100% >85% >80% *Includes beneficial native plants in that category that are naturally recruiting volunteers • Less than 10% invasive vegetation during any monitoring event • The establishment of 3 species of native trees and 4 species of native shrubs at the end the the monitoring period. 12.0 Monitoring hf€uiitrruug shall to condivtheci arethally fitr 5 years in accordance with the mingatots mmutmueig;am 12.1 Vegetation Monitoring: Sample points or transects will be established for vegetation monitoring, and photo -points established from which photos will be taken throughout the monitoring period. Linear transects are the preferred method for vegetation monitoring for this site. No less than one (1) 100-foot transect per 10,000 square feet of area will be established in the mitigation/restoration area. Permanent transect location(s) must be identified on mitigation/restoration site plans m the first monitoring report (they may be drawn on approved mitigation/restoration plans by hand). Plots located at the end of each transect shall detail herb, shrub, and tree aerial cover at radii of l as, 5m, and I tin respectively, using the nr",,.,-mien„es r rev. method or other nceentable field method. Monitoring 12,2. Fhotopotnta No km than oree 11I pp,metp to point pet' 10," squarefaro ar"" coiligaliVilreggratiOil will to b i ' within Om mitigthiardnisthastam. amp Photographs will be teen from them points to visually record the co -§on.. Mite mitininamilraithin area Plythim shah he takes thirsolly bvw z Ate _ mid Scum -oft - PO (prior t tmf'dreup),. unless otherwise specified. 12.3 Ra eir-t - M mg r Oda be submitted by December 31 of each yam &Pinstbe nr[ -Mg ;mot As applicable, monitoring reports must include description/data for: • Site plan and location map • Historic description of project, including date of installation, current year of monitoring, restatement of mitigation/restoration goals, and performance standards • Font staNwal, -vt . ar fiat cssxmage from z.: rty Math conthanam (try daft),end imMthathod. ofsamara-us melhaiininu m the thrimat of maistaing noff-c - - • Site hydrology, including titan el -- o depth to youndthatm, firm tsar Maio hyithetolla thaptara, r r mica g i evalta a, rips . -;s t . KC.r • Slope .dsi site stair City, any grl.KnI.M5 or special features • Diffica pooditom,ea. uasncrtmding lad mei use by humans, wild and domestic creatures • Observed wildlife, including amphibians, avians and others • Assessment of nuisance/exotic biota and recommendations for management • Soils, including texture, Munsell color, rooting and oxidized rhizoshperes • Receipts for off -site disposal of any dumping, weeds, or invasive plants • Receipts for any structural repair or replacement • 4"x6" color photograph taken from permanent photo -points as shown on Monitoring/Restoration plan. • Summary of maintenance and contingency measures proposed for next season and completed for past season. 12.4 Defrciences: Any deficiency discovered during any monitoring or inspection visit must be corrected within 60 days of approval by City of Tukwila 12.5 Contingency Plan: Should any monitoring report reveal the mitigation has failed m whole or in part, and should that failure be beyond the scope of routine maintenance, a Contingency Plan will be submitted. The Contingency Plan may range in complexity from a list of plants substituted, to cross -sections of proposed engineered structures. Once approved, it may be installed, and will replace the approved mitigation/restoration plan. If the failure rs substantial, the City of Tiikwila may extend the monitoring period for that mitigation 13.0 Bond Prior to beginning any work, the Pemrttee must provide a mitigation/restoration bond or igmnem zt City of Tukwila procedures. A bond quantity aTre be 3 on all elements of the mingationietet inazi ttiqn cost, plm contingency fees has been momnioadlo be $ 20,013.20 which will iVffie amount of the iniingmlanditheri. bond the Permittee is rewire vr€ ide REVISED FINAL WETLAND MITIGATION PLAN TUKWILA POND Tukwila, Washington Prepared for Wig Properties LLC-SS 4811 SE 134th Place SE Bellevue, Washington 98006 Prepared by: Chad Armour LLC 6500 126th Avenue SE Bellevue, Washington 98006 (425) 641-9743 August 2006 RECENED AUG 14 2006 1 o ihf u;,i t'f 29 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington TABLE OF CONTENTS 1. EXECUTIVE SUMMARY 1 2. PROJECT DESCRIPTION 3 2.1 PROJECT LOCATION 3 2.2 RESPONSIBLE PARTIES 3 2.3 DESCRIPTION OF THE OVERALL PROJECT 3 3. BASELINE INFORMATION 4 3.1 WETLANDS ON THE PENNEY SITE 4 3.1.1 Wetland A 4 3.1.2 Wetland B 4 3.1.3 Wetland C 4 3.1.4 Wetland D 4 3.1.5 Wetland E 5 3.1.6 Wetland F 5 3.1.7 Wetland Ratings 5 3.1.8 Wetland Functions 5 3.1.9 Fauna Associated with the Penney Wetlands 5 3.2 TUKWILA POND SITE 5 3.2.1 Existing Vegetation 6 3.2.2 Existing Soils 6 3.2.3 Existing Hydrology 6 3.2.4 Wetland Ratings 7 3.2.5 Wetland Functions 7 3.2.6 Tukwila Pond Fauna 7 3.3 PRECIPITATION ANALYSIS 7 4. PROBABLE IMPACTS OF THE PROPOSED DEVELOPEMENT 8 4.1 SHORELINE PROTECTION 8 4.2 HYDROLOGIC SUPPORT 8 4.3 STORM/FLOOD WATER ABATEMENT 9 4.4 GROUNDWATER EXCHANGE 9 4.5 WATER QUALITY IMPROVEMENT 10 4.6 BIOLOGICAL SUPPORT 10 5. MITIGATION APPROACH 11 5.1 CODE COMPLIANCE 11 5.1.1 Permitted Alterations 11 5.1.2 Mitigation Sequencing 12 5.1.3 Mitigation Plans 12 5.1.4 Mitigation Location 13 5.2 RATIONALE FOR CHOICE 13 5.2.1 Case Study 13 5.2.2 Projected Conditions of the Mitigation Site 14 C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc ii 08/10/06 Chad Armour LLC 30 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington 5.3 CONSTRAINTS 14 5.4 GOALS AND OBJECTIVES OF THE MITIGATION PLAN 14 5.4.1 Goals 14 5.4.2 Objectives 14 5.5 PERFORMANCE STANDARDS 15 5.5.1 Hydrology 15 5.5.2 Soil 16 5.5.3 Vegetation 16 5.5.4 Structure 17 6. CONSTRUCTION PLAN 17 6.1 HYDROLOGY 18 6.2 SOILS 18 6.3 VEGETATION 18 6.4 HABITAT STRUCTURES 19 6.5 INSTALLATION SEQUENCE 19 7. MONITORING PLAN 20 7.1 PRE -CONSTRUCTION MONITORING 20 7.2 CONSTRUCTION MONITORING 20 7.3 POST -CONSTRUCTION MONITORING 20 7.3.1 Hydrology 21 7.3.2 Soils 21 7.3.3 Vegetation 21 7.3.4 Fauna 21 7.3.5 Habitat Structures 21 7.3.6 Water Quality 21 7.3.7 Buffers 21 8. SITE PROTECTION 22 9. MAINTENANCE PLAN 22 10. CONTINGENCY PLAN 22 10.1 POST A BOND 23 10.2 INSTALL PLANTS SUITED TO SEASONAL FLOODING 23 10.3 ANNUAL MONITORING FOR THE FIRST 5 YEARS 23 10.4 REMOVE ALL REED CANARYGRASS 23 10.5 INSTALL ADDITIONAL PLANTS AS NECESSARY 23 11. SCHEDULE 24 12. PERFORMANCE BOND 24 13. LIMITATIONS 24 C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc 08/10/06 Chad Armour LLC 31 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 REFERENCES TABLES Wetland Functional Assessment of Various Wetlands Pre- and Post -Construction Water Detention and Water Quality Comparison Groundwater and Surface Water Elevations in the Tukwila Pond Mitigation Area Comparative Analyses of Precipitation Records Functional Wildlife Habitat of Various Wetlands Plants to be Installed on the Mitigation Site FIGURES Vicinity Map Wetlands on the Penney Site Upland Location Plan Comparative Precipitation Analyses Grading Plan Planting Plan APPENDIX A U.S. Army Corps of Engineer Jurisdictional Determination of Wetlands on the Penney site U.S. Army Corps of Engineer Recommendation for Off -Site Mitigation Washington Department of Ecology Recommendation for Off -Site Mitigation U.S. Army Corps of Engineer Nationwide Permit 39 Notification APPENDIX B Wetland Rating for the Penney site Wetland Rating for the Tukwila Pond site Wetland Rating for the Mitigation site — Existing Conditions Wetland Rating for the Mitigation site — Projected Conditions C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc iv 08/10/06 Chad Armour LLC 32 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington 1. EXECUTIVE SUMMARY Wig Properties LLC-SS (Wig) plans to construct the Southcenter Shopping center on the 18.77- acre Penney warehouse distribution site in Tukwila, Washington (Figure 1). To do so, Wig proposes to fill 1.16 acres of wetlands that developed on fill soil placed on the Penney site in the late 1960s (Figure 2). Based on the City of Tukwila's (Tukwila) wetland rules, four of the six Penney site wetlands meet the criteria for Type 3 wetlands. The other two are unregulated. The U. S. Army Corps of Engineers (Corp) determined that only one of the six wetlands on the Penney site is jurisdictional and therefore regulated by the Corps (Appendix A). All six of the Penney site wetlands are regulated by the Washington Department of Ecology (Ecology). As a whole the wetlands on the Penney site exhibit low wetland functions because they are small and support immature plant communities that developed on imported fill soils (Table 1). Upon closer inspection, the Penney site wetlands exhibit high water quality functions and low hydrologic and habitat functions. The road ruts that support wetlands store water that would otherwise be released quickly to the lower Green River. They also provide limited water quality improvement and biological support. To mitigate for filling the Penney site wetlands, Wig proposes to create and enhance a total of 3.48 acres of lacustrine emergent and open water wetland dominated by reed canarygrass (Phalaris arundinacea). The mitigation site is located in the southeast quadrant of the 24-acre Tukwila Pond site. It is surrounded by open water, scrub -shrub and forested wetland, forested upland, and upland shrubs. The Tukwila Pond site as a whole, rates at the low end of Category II wetlands (Appendix B). Its water quality functions rate high and it's hydrologic and habitat functions are rated as moderate. The mitigation site currently rates as a solid Category III wetland. It has a moderate rating for water quality and hydrologic functions and a low habitat function. Following completion of mitigation and at the end of the 10-year monitoring and maintenance effort, the Mitigation site is projected to function as a high end Category II wetland. The Tukwila Pond site is located about 1,000 feet northeast of the Penney site. The Tukwila Pond was selected for mitigation for the following reasons: • The quality of the existing wetland at the Tukwila Pond site can be substantially improved (Table1); • Both Ecology and the Corps prefer that mitigation occur off site (Appendix A); • The sensitive areas regulations allow for off site mitigation; • Tukwila's long-term plans include enhancing degraded portions of the Tukwila Pond site; • The mitigation site is located in the same drainage basin as the Penney site; and • The mitigation site is bounded by existing open water and forested wetlands as well as upland forest and shrub plant communities. In addition to providing compensation for wetland loss, the benefits of the wetland mitigation plan include: C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.docl 08/10/06 Chad Armour, LLC 33 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington • Increasing the complexity of the Tukwila Pond site; and • Increasing the detention capacity of the Tukwila Pond. In addition to providing these benefits, the wetland mitigation plan is designed to more than replace the wetland functions that will be lost on the Penney site. Filling the Penney site wetlands will have minimal impact on the hydrological support function because their contribution to base flow is very small. Conversely it will have a positive effect on floodwater abatement and water quality improvement. The shopping center's stormwater management system together with the new detention capacity on the Mitigation site represents a 574 percent increase over existing conditions (Table 2). Similarly, the shopping center's water quality system and landscaping together represents a 1,345 percent increase in water quality treatment capacity. Replacing the immature forest and meadow habitat present on the Penney site with four wetland classes, including open water, will more than offset the lost habitat functions (Table 1). Wig recognizes that it is likely that some of the plants installed on the Mitigation site will not survive the seasonal flooding typical of the Tukwila pond. Wig also recognizes that seasonal flooding tends to favor reed canarygrass. To reduce these potentials Wig will: • Install plants that tolerate seasonal flooding; • Monitor the Mitigation site for 10 years — annually for the first 5 years; • Install new plants annually to replace those that are lost; and • Post a bond sufficient to cover the cost of replanting the Mitigation site. C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc2 Chad Armour, LLC 08/10/06 34 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington 2. PROJECT DESCRIPTION This plan presents information about the proposed Southcenter Square Shopping Center project (Proposed Development), the wetlands that are present on the Penney site, the land present in the southeast quadrant of the Tukwila Pond site, and the mitigation plan designed to compensate for lost wetland functions due to the Proposed Development. 2.1 Project Location The Proposed Development is located in Tukwila, Washington (King County) in Sections 26, Township 23 North, Range 4 East (Willamette Meridian) (Figure 1). It is bounded by Southcenter Parkway to the west, Minkler Boulevard to the south, the Bon distribution warehouse to the north, and a business park to the east. The Mitigation site is located within a larger parcel typically referred to as the Tukwila Pond. The Mitigation site is located west of Andover Parkway West (Andover). 2.2 Responsible Parties The following key people are responsible for this project: Ms. Leshya Wig, Project Manager Wig Properties LLC-SS 4811 134th Place SE Bellevue, Washington 98006 (425) 957-4774 Ms. Moira Bradshaw, Sr. Planner City of Tukwila Department of Community Development 6300 Southcenter Boulevard Tukwila, Washington 98188-2544 (206) 431-3651 Mr. Chad Armour, Principal Chad Armour LLC 6500 126th Avenue SE Bellevue, Washington 98006 (425) 641-6743 Mr. Armour prepared this wetland mitigation plan and delineated the wetlands on the Penney site and the central uplands on the Mitigation site (Figure 3). 2.3 Description of the Overall Project Wig plans to construct a commercial shopping center on the 18.77-acre Penney site. There are currently two buildings on the western 13.55 acres of the Penney site. The eastern 5.22 acres is the location of immature deciduous forest and meadow plant communities that developed on fill soils. These soils were placed on the site some 35 years ago (Armour, 2004). To build the shopping center, Wig proposes to fill 1.16 acres of low quality emergent and forested wetlands. To mitigate for filling these wetlands, Wig proposes to enhance and/or create 3.48 acres of existing upland and wetland present on the Tukwila Pond site. This includes creating wetland at a ratio of 1.5:1, enhancing degraded wetland at a ratio of 3:1, and enhancing degraded wetland at a ratio of 1:1. At the end of the 10-year monitoring the functional value of the created and C:/Jobs/Wig/Revised Final Wetlan Mitigation Plan.doc3 08/10/06 Chad Armour, LLC 35 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS enhanced wetlands on the Mitigation site will be considerably greater than the functions of the existing wetlands on both the Penney and Tukwila Pond sites (Tables 1 and 2). 3. BASELINE INFORMATION Chad Armour LLC (Armour) delineated the wetlands on the Penney site in April 2004. Armour installed and measured the water levels in 14 shallow groundwater monitoring wells on the Mitigation site from October 2004 to the present. Bush, Roed & Hitchings, Inc. (BRH) is Wig's civil engineering consultant. BRH surveyed the delineated wetland boundaries on the Penney site, calculated pre- and post -development stormwater runoff on the same, and prepared the grading plan for the Mitigation site. 3.1 Wetlands on the Penney Site There are six wetlands located on the Penney site (Figure 2). 3.1.1 Wetland A Wetland A is an isolated Type 3 wetland that covers 13,718 square feet (0.32 acre). Its most notable feature is a rutted road. Grasses and herbs dominate most of Wetland A, including the road. Trees dominate a small portion of this wetland. The forested portion of Wetland A occupies 2,698 square feet; almost 20 percent of the wetland. During the rainy season standing water about 6 inches deep is present on about 75 percent of the wetland. 3.1.2 Wetland B Wetland B is an isolated Type 3 wetland that covers 24,461 square feet (0.57 acre). Trees dominate the western half of Wetland B. Emergent herbs typically growing in a deeply rutted road dominate the remaining wetland. During the rainy season standing water averages about 6 inches deep; however, can be up to 1.5 feet deep in places. 3.1.3 Wetland C Wetland C is an isolated Type 3 wetland that covers a total of 6,305 square feet (0.15 acre). It includes a forested area that covers 40 percent of the wetland and a rutted road. The road contains standing water during the rainy season and supports emergent vegetation. The understory of the forested area is generally devoid of vegetation, presumably as a result of standing water. During the rainy season 100 percent of this wetland is covered with about 6 inches of standing water. 3.1.4 Wetland D Wetland D is a Type 3 wetland that covers 3,943 square feet (0.09 acre). Himalayan blackberry (Rubus discolor) shrubs, grasses, and herbs dominate it. Surface water accumulates in this wetland during the rainy season. This water discharges west to the asphalt apron and associated stormwater drain located on the developed portion of the distribution center. After the water enters the catch basin, it flows into a series of pipes (sizes range from about 6 inches to 66 inches in diameter) and swales before being discharged into a King County regional stormwater detention pond. This water is then pumped into the Green River (Clark, 2004). Wetland D is the only wetland considered jurisdictional by the Corps (Appendix A). C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc4 08/10/06 Chad Armour, LLC 36 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington 3.1.5 Wetland E Wetland E covers 179 square feet (<0.01 acre) and is dominated by soft rush (Juncus effusus). The slight grade of this wetland precludes standing water during the rainy season. This isolated wetland is too small to be regulated by Tukwila, but is regulated by Ecology. 3.1.6 Wetland F Wetland F is an isolated wetland that covers 1,971 square feet (0.05 acre). Trees dominate the central 40 percent of this wetland. The remainder of Wetland F is dominated by emergent plant species. Like all of the other Penney site wetlands, a rutted road represents a significant portion of this wetland. During the rainy season standing water about 6 inches deep is present on about 50 percent of the wetland. As with Wetland E, this isolated wetland is too small to be regulated by Tukwila, but is regulated by Ecology. 3.1.7 Wetland Ratings Based on Tukwila's criteria (Tukwila, 2005), the wetlands individually and collectively are rated as Type 3 wetlands. The wetlands are classified as a Category III wetland using Ecology's wetland rating system (Appendix B). 3.1.8 Wetland Functions Based on the revised Washington State Wetland Rating System for Western Washington (Hruby, 2004), the Penney site wetlands are rated at the low end of Category III wetlands (Table 1). As a whole the wetlands on the Penney site exhibit low functions because they are small and support immature plant communities that developed on imported fill soils. When the wetland functions are partitioned, the Penney site wetlands exhibit moderate water quality and habitat functions and low hydrologic functions. They rated high for water quality because very little surface water flows off of the site and the wetlands are surrounded by urban development. The road ruts on the site that are wetlands store water that would otherwise be released quickly to the lower Green River. We assume that this stored water infiltrates into the soil and contributes to the regional groundwater system. These open water areas also provide some habitat for waterfowl, and the trees and shrubs provide some nesting opportunities for small birds. 3.1.9 Fauna Associated with the Penney Wetlands During one of our site visits we recall observing mallard (Anas platyrhycos) and American crow (Corvus brachyrhyncos). The Penney site likely attracts and supports a number of bird species typically attracted to western Washington's urban and suburban habitats. Small mammals could also be present. There are three listed threatened species reported to be located in the vicinity of the Penney site. They are Chinook salmon (Oncorhynchus tshawytscha), bull trout (Salvelinus confluentus), and bald eagle (Haliaeetus leucocephalus). The salmonids are present in the Green River. An abandoned bald eagle nest was reported about 2 miles southwest of the Penney site (WDFW, 2004). 3.2 Tukwila Pond Site The Tukwila Pond site is located about 1,000 feet north northeast of the Penney site (Figure 1). It occupies approximately 24 acres, more than 19 acres of which are open water. The Tukwila Pond site is bounded by uplands and urban development. Its buffers are narrow, confined to short steep slopes, and support trees and shrubs. Relatively tall (-75 foot) black cottonwood C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc5 08/10/06 Chad Armour, LLC 37 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS (Populus balsamifera) trees are rooted in the buffer along the east side of the Tukwila Pond site. The southeast corner of the Tukwila Pond site is the location of the Mitigation site. This area covers a total of 3.48 acres. 3.2.1 Existing Vegetation There are five plant communities in the southeast corner of the Tukwila Pond site. A forest dominated by black cottonwood is located along the eastern perimeter of the Tukwila Pond site. The southern boundary is dominated by Himalayan blackberry. Both of these plant communities function as uplands. Most of the Tukwila Pond site is dominated by a monoculture of reed canarygrass (meadow). A portion of this meadow functions as upland (Figure 3). A Himalayan blackberry thicket is present at the south end of this upland. A forest composed of Pacific willow (Salix lasiandra) and red -osier dogwood (Corpus stolonifera) separate the meadow from the pond proper. The steep slopes of the railroad grade along the southern site boundary are covered with a tangle of blackberry and the flats with red -osier dogwood in two places. A depression near the southeast corner of the Mitigation site supports rooted floating vegetation. 3.2.2 Existing Soils A 1986 geotechnical engineering report on the Mitigation site described the near -surface soils as silty fine sand and sandy silt (Dames and Moore, 1986). When Tukwila delineated the wetlands on the Tukwila Pond site, they described the near -surface soils as silt loam. 3.2.3 Existing Hydrology Permanent open water is present in the Tukwila Pond site throughout the year. We understand that the pond is groundwater fed and know that there are seasonal inputs from precipitation and runoff from adjacent built up areas. On occasion Green River flood water is routed to the pond. We understand that the pond is relatively shallow, averaging about 2 to 3 feet deep, with the deepest point about 6 feet below the surface (Partee, 2004). A 1988 construction drawing for a site to the north indicated a static pond water level of ±13.0 feet (Barghausen, 1988). The same drawings indicate that the flood elevation is 25.8 feet. In 2005 and 2006 we found the pond elevation to range from 19.2 to 19.3 feet in April (Table 3). The elevation of the water in the pond is controlled by a 15 inch corrugated metal culvert (CMP) fitted with a flap gate located on the east side of the Mitigation site adjacent to Andover. When the lower Green River is in flood, Tukwila opens the flap gate to allow flood water to enter the pond for temporary storage. This stored water is released back into the river after the flood crest has passed (Howat, 2004). The invert elevation of this CMP is18.8 feet (BRH, 2004). We have observed that a significant portion of the Mitigation site can be flooded during the rainy season (Figure 3). The southeast corner of the Mitigation site is flooded with water as much as 5 feet deep. Standing water in this depression extends from the area southeast of the upland to the flap gate CMP (Figure 3). The pond proper floods the western edge of the Mitigation site. In April 2005 and 2006 we measured the elevation of the pond to be about 19.2 feet (Table 3). During the same month the elevation of the standing water in the southeast corner of the Mitigation site was about 18.1 feet in 2005 and 18.4 feet in 2006. Apparently the flap gate CMP allows the smaller body of water to drain quickly, and retards pond drainage. When the mitigation area is flooded the surface of the water is covered with pieces of reed canarygrass. We assume that this flotsam includes reed canarygrass seed. C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc6 Chad Armour, LLC 38 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS 3.2.4 Wetland Ratings There are several lacustrine wetland classes present on the Tukwila Pond site. A portion of the proposed Mitigation site is emergent and open water seasonally flooded wetland. To the west is a forested wetland and beyond that is open water (Cowardin et al., 1979). Based on Ecology's wetland rating system for western Washington, the wetland present on the Tukwila Pond site is classified as a Category II wetland (Appendix B). 3.2.5 Wetland Functions The Tukwila Pond site wetland as a whole, rates at the low end of Category II wetlands (Table 1). It is completely surrounded by impervious surfaces associated with retail and commercial development. The Tukwila Pond wetland has a good mixture of open water, emergent, scrub - shrub, and forested wetland habitat, as well as unmanaged upland buffers. Its water quality functions rate high because it temporarily stores untreated stormwater prior to discharge to the Green River. It's hydrologic and habitat functions are rated as moderate (Appendix B). Because the pond is not regularly flushed, is shallow, has a limited outflow, and during the dry season the size of the pond shrinks, the quality of the water is poor. This is particularly so in the summer when algal blooms rob the water of oxygen. The pond can be flushed during the rainy season. When viewed independently of the Tukwila Pond site, the Mitigation site rates as a Category III wetland (Table 1). The thick mat of reed canarygrass prevents other species of plants — including woody shrubs and trees — from becoming established. This persistent monoculture is unattractive to most animals. It has a moderate rating for water quality because it is covered solely with herbaceous vegetation. It exhibits moderate hydrologic functionality because it temporarily stores untreated stormwater during the rainy season. It provides low habitat functions because of the predominance of the reed canarygrass monoculture. 3.2.6 Tukwila Pond Fauna Many different animal species have been reported on the Tukwila Pond site. Waterfowl are attracted to the Tukwila Pond in an otherwise highly urbanized area. It is reported to be used as permanent habitat for some animals and as a migratory stopover for others (Watershed Dynamics, 1994). During periods of low water in the fall and winter, mudflats form on the southern end of the pond. These mudflats provide foraging opportunities for waterfowl. And the pond provides foraging opportunities for diving birds such as pied -billed grebe (Podylimbus podiceps) and double-breasted cormorant (Phalocrocorax auritus). During the summer the limited diversity afforded by thick vegetation limits the value to waterfowl and marsh birds. Brown bullhead (lctalurus nebulosus) is present in the pond. Few mammals are reported for the Tukwila Pond site. Muskrat (Onodantra zibethica) haul -out sign was reported in the southeast corner of the Tukwila Pond site. Bull frog (Rana catesbeiana) is found near the edge of open water. The only reported priority species on the site is the great blue heron (Ardea herodias). A report prepared by the WDFW for the Penney site also covers the Tukwila Pond and Mitigation sites. The WDFW report indicates that no priority species are present on or near the Tukwila Pond site. 3.3 PRECIPITATION ANALYSIS As indicated in Section 3.3.2, the surface water elevation of the Tukwila Pond is affected by groundwater, runoff from surrounding areas, and on occasion flood water from the Green River. All of these factors are related to precipitation. As shown on Figure 4 the 2004/2005 water C:/JobsNVig/Revised Final Wetland Mitigation Plan.doc7 Chad Armour, LLC 08/10/06 39 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS years was somewhat drier than normal for the first 5 months (October through February), normal in March and June, and somewhat wetter than normal in April and May (Table 4). The 2005/2006 water year began normally (October and November) but quickly became wetter than normal in December and January, particularly in January when nearly twice the amount of expected rain fell on the region (Seattle Times, 2004, 2005, & 2006). The following two months of the 2005/2006 water year (February and March) were drier than normal and April exhibited a near normal amount of precipitation. 4. PROBABLE IMPACTS OF THE PROPOSED DEVELOPEMENT Wetlands have several physical, chemical, and biological processes or attributes that are important to the ecosystem. These wetland functions include shoreline protection, hydrologic support, storm/flood water abatement, groundwater exchange, water quality improvement, and biological support. Each of these functions and the probable impact of site development are discussed in detail in the following subsections. 4.1 Shoreline Protection Wetlands provide shorelines protection from erosion caused by tidal action along coasts, currents in rivers and streams during flooding, and wind or wake generated erosion along coastlines. Wetlands reduce shoreline erosion by absorbing or dissipating wave energy, by binding and stabilizing shoreline substrates, and by enhancing suspended sediment deposition (Hammer, 1992). None of the wetlands on the Penney site are located adjacent to shorelines. Therefore, filling these wetlands will have no impact on shoreline functions. We anticipate that limited areas of soil adjacent to the Tukwila Pond shoreline will be exposed as part of mitigation. As such, a limited amount of erosion from wave action will likely occur the first couple of years following construction. 4.2 Hydrologic Support Hydrology is the single most important factor for establishing and maintaining wetlands and wetland processes. Hydrologic inputs include precipitation, surface water runoff, groundwater, tides, and flooding. Water inputs are almost always the major source of nutrients to wetlands. Water outflows often remove biotic and abiotic material from wetlands. These physiochemical modifications of the environment have a direct impact on the biotic response in wetlands (Mitsch and Grosselink, 1986). During the winter rainy season surface water from Wetland D (one of the Penney site wetlands) flows into a nearby catch basin. From this parking lot catch basin, water flows through a man- made storm water conveyance system into a detention pond where it is pumped into the Green River. The other five wetlands at the Penney site are isolated depressions with no direct connection to nearby streams. We assume that the water that accumulates in these depressional wetlands percolates through the soil profile and contributes to the base flow of the Green River. Filling the Penney site wetlands will have a minimal impact on the hydrological support function because the contribution to Green River base flow is extremely small. C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc8 08/10/06 Chad Armour, LLC 40 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington 4.3 Storm/Flood Water Abatement Wetlands can have an effect on the peak flows of floodwaters in streams and on their base flows during dry periods. Floodwater modification is most often identified with bottomland hardwood swamps. Forested wetlands in river floodplains can reduce the height of downstream floodwater peaks by acting as natural reservoirs and directly obstructing and slowing flows. By retaining stormwater and releasing them at a controlled rate, wetlands augment base flows (Hammer, 1992). Tukwila's stormwater management strategy is to release stormwater into the Green River before flood flow reaches Tukwila. This strategy limits the potential for high water in the river from blocking runoff generated in the city and reduces the potential for flooding beyond the river's levees. In support of this strategy, Tukwila will require no detention for the existing impervious surfaces on the Penney warehouse distribution site, but will require Wig to detain runoff from the pervious surfaces currently present on this site. The development plan has these pervious surfaces — which cover 5.8 acres of the Penney distribution site — being converted to impervious surfaces. Based on visual observations over a period of two winters, we estimate that the wetlands on the Penney site provide approximately 16,875 cubic feet (cf) of detention capacity (Table 2). This capacity assumes that all but one of the wetlands stores water averaging 6 inches deep throughout the rainy season. It also assumes that standing water represents 100 percent of the surface area of Wetlands C and D, 75 percent of Wetland A, and 50 percent of Wetlands B and F. Wetland E is located on a slight slope and retains no surface water. The wetland mitigation plan includes removing a significant quantity of soil from the Mitigation site (Figure 5). This action will increase the detention capacity of the Tukwila Pond site by about 46,900 cf (BRH, 2006). Using the King County Runoff Time Series (KCRTS) method for estimating runoff, Tukwila will require 26,200 cf of storage for the additional 5.8 acres of impervious surfaces that will be created by the Planned Development (BRH, 2004). This is a conservative estimate because the model assumes that the impervious surfaces are occupied by a mature Douglas -fir (Pseudotsuga menziesii) forest. The impervious surfaces are actually represented by 0.6 acre of mowed lawn and 5.22 acres of immature forest and meadow. The volume of water to be detained on the Planned Development is somewhat less than three times the stormwater holding capacity of the Penney site wetlands (50,000cf/16,875cf). When the added capacity on the Mitigation site is also factored into the equation, the increase stormwater holding capacity of the Planned Development represents nearly a 575 percent increase over existing conditions (Table 2). Thus the mitigation plan compensates for the lost stormwater holding capacity of the Penney site wetlands many times over. 4.4 Groundwater Exchange Groundwater recharge has been shown to occur in isolated wetlands such as prairie potholes, cypress domes, and floodplain forests. A few wetlands in Wisconsin, North Dakota, and Florida were shown to have direct connections and contributed significantly to groundwater. But other wetlands have been shown to have little influence on groundwater or, in some cases, the wetland is present because of surfacing groundwater (Hammer, 1992). C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc9 08/10/06 Chad Armour, LLC 41 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington It is likely that the Penney site wetlands do not owe their existence to surfacing groundwater. Rather the precipitation that accumulates in these wetlands seasonally likely contributes to the regional groundwater system. This phenomenon is thought to be largely due to the original soil being covered some 35 years ago with up to 10 feet of imported fill soil (Armour, 2004). 4,5 Water Quality Improvement Wetlands have the ability to remove pollutants from water, through a variety of physical, chemical, and biological processes. Water purification functions of wetlands are dependent on four principal components — vegetation, water column, substrates, and microbial populations. With respect to water quality improvement, the principal function of vegetation in wetlands is to provide environments for microbial populations. Not only do plants in the water column obstruct flow and facilitate sedimentation they also provide habitat for microbes. In addition to attachment surfaces for microbes, substrates provide physical support for plants, and surfaces for chemical reactions. The water column transports substances and gasses to microbial populations, carries off by-products, and provides matrix for biochemical processes (Hammer, 1992). No surface water flows onto the eastern 5.22 acres of the Penney warehouse distribution site. Only surface water from Wetland D flows off of this area. As such, sediment retention is limited and most of the water quality improvement capacity of Penney site wetlands is provided by microbes attached to vegetation and to soil particles. The water flowing from Wetland D receives some water quality treatment when it flows through grass -lined ditches and is detained in the regional stormwater pond adjacent to the Green River. The water quality treatment capacity of the Penney wetlands is 1.16 acres. The Planned Development specifies treating approximately 14 acres of pollution -generating surfaces (i.e., asphalt). Surface water runoff from the asphalt will be directed to a water quality treatment system. The water quality treatment system will be designed and maintained in accordance with Tukwila engineering standards. The Penney site currently has 7.1 acres of untreated pollution -generating surfaces (BRH, 2006). In addition to the water quality treatment system, the Planned Development will have about 1.5 acres of landscaping. Most of the landscaping will be located around the perimeter of the shopping center. This landscaping represents pervious surface directly connected to the regional groundwater system. The microbes attached to soil particles in the landscaped areas will treat water that falls on these areas. Wig will provide water quality treatment far in excess of that provided by the Penney site wetlands (Table 2). The water quality treatment system, together with the landscaped areas, represents about a 1345 percent increase in water quality treatment capacity relative to these wetlands. The total increase is even larger when the relatively clean water entering the Penney site wetlands is compared to the water entering the treatment system, which contain petroleum hydrocarbons and metals. 4.6 Biological Support Wetlands produce many diverse forms of life and provide habitat for countless others. Wetlands are dynamic, transitional, and dependent on disturbance. Wetlands receive, hold, and recycle nutrients continually washed from upland regions. The combined interactions of abiotic and biotic factors create a diversity and abundance of habitats that make wetlands the most C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.docl0 08/10/06 Chad Armour, LLC 42 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS important wildlife habitat. Basic productivity of many wetlands far exceeds the most fertile farm fields (Hammer, 1992). The Penney site wetlands offer limited biological support functions because they are small and support immature or simple plant communities. Ducks use the wetlands seasonally during periods of prolonged precipitation. Other animals likely utilize the wetlands when they are dry. Filling the Penney site wetlands will have very little impact on the biological support function of these wetlands. Listed salmonids cannot access the wetlands and bald eagles are not known to be present on the Penney site. The immature black cottonwood trees on the Penney warehouse distribution site are too small (<12 inches in diameter and 70 feet tall) to support nesting and/or roosting bald eagles. 5. MITIGATION APPROACH After carefully evaluating several scenarios, Wig concludes that filling 1.16 acres of wetlands on the Penney site is unavoidable. With the exception of the Tukwila Pond site, options for mitigating for lost wetland functions are limited. In exchange for filling the Penney site wetlands, Wig proposes to create and/or enhance 3.48 acres of degraded upland and wetland located at the Tukwila Pond site. Off -site mitigation makes the most sense in this case because: • The quality of the existing wetland at the Tukwila Pond site can be substantially improved (Table1); • Both Ecology and the Corps prefer that mitigation occur off site (Appendix A); • Tukwila's rules allows for off site mitigation; • Tukwila's long-term plans include enhancing degraded portions of the Tukwila Pond site; • The Mitigation site is located in the same drainage basin as the Penney site; and • The Mitigation site is bounded by existing open water and forested wetlands as well as upland forest and shrub plant communities. 5.1 Code Compliance 5.1.1 Permitted Alterations Per Tukwila's sensitive area regulations, any use or development of wetlands requires the review and approval of the Director of Community Development (TMC 18.45.090). Requests may be approved if the alteration does not adversely affect water quality; fish, wildlife, or their habitat; drainage or stormwater detention capabilities; lead to unstable earth conditions or create an erosion hazard; be materially detrimental to any other property; and have an adverse effect on any other sensitive areas (TMC 18.45.090.6.1). Isolated wetlands exhibiting low functions that formed on fill material in highly disturbed environmental conditions may be altered (TMC 18.45.090.B.6). Per these requirements, the Penney wetlands clearly qualify as wetlands that may be altered (Tukwila, 2005). C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.docl l 08/10/06 Chad Armour, LLC 43 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS 5.1.2 Mitigation Sequencing Tukwila requires that development proposals demonstrate a reasonable effort to avoid and minimize impacts to wetlands and their buffers. If avoidance and minimization are not possible, the preferred order of compensation is: • Restoring wetlands on upland sites that were formerly wetlands; • Enhancing significantly degraded wetlands; • Creating wetlands on disturbed upland sites (TMC 18.45.090.C). Wig cannot avoid or minimize filling the wetlands on the Penney site because Wig's tenant - driven key criteria are that the land be at least 18 acres in size and be located on the main strip of Southcenter Parkway. There are no other properties that meet these criteria. Wig evaluated off site options including the Macadam site, River Bend site, and a site off of Strander Boulevard. The Macadam site was too steep and not large enough to be considered a viable option. The River Bend site was too small and as much as 15 feet of soil would need to be removed to create wetlands. The Strander site is owned by the Boeing Corporation and is not readily available for sale. None of these three options represented upland sites that were formerly wetlands. The Mitigation site is a significantly degraded wetland with the potential to be enhanced. Enhancing this degraded wetland is supported by the Corps, Ecology, and Tukwila staff. Here Wig can create four wetland classes where only one wetland class now exists. Enhancement will significantly increase the functional value of the degraded wetland. There is no opportunity to create wetlands on disturbed upland sites in Tukwila. After evaluating the attributes of four potential mitigation sites, Wig concluded that enhancing the degraded wetland present on the Tukwila Pond site was the only reasonable available option. Further, on site mitigation has been discouraged by both the Corps and Ecology (Appendix A). 5.1.3 Mitigation Plans Per section 18.45.090.D of the wetland regulations, "wetland and/or buffer relocation may be allowed only when a mitigation plan clearly demonstrates that the changes would be an improvement of wetland and buffer quantitative and qualitative functions." Further, the plan shall "show how water quality, wildlife and fish habitat, and general wetland quality would be improved." The close proximity of available degraded upland and wetland adjacent to a large expanse of open water, scrub -shrub and forested wetland, and upland in an urban environment provide a unique opportunity to mitigate for impacts to wetlands. The enhanced wetland area will improve the habitat function of the existing wetland (Table 1) and be composed of four wetland classes — open water, forested, scrub -shrub, and emergent wetland (Figure 6). The existing Mitigation site wetland is composed of two wetland classes. The enhanced wetland will be bordered on the east by upland forest, on the south by wetland and upland shrubs, and on the northwest by a combination of existing open water and forested wetland. The resultant plant communities in conjunction with open water will provide excellent habitat for wildlife (Table 5). C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.docl2 Chad Armour, LLC 08/10/06 44 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS 5.1.4 Mitigation Location According to Section 18.45.090.E of the wetland regulations, on -site mitigation shall be provided, except where the application can demonstrate that: a) On -site mitigation is not scientifically feasible due to problems with hydrology, soils, waves, or other factors; or b) Mitigation is not practical due to potentially adverse impact from surrounding land uses; or c) Existing functional values created at the site of proposed restoration are significantly greater than lost wetland functional values; or d) That established regional goals for flood storage, flood conveyance, habitat or other wetland functions have been established and strongly justify location of mitigation at another site. On -site mitigation is not preferred because the Penney site wetlands are very small, surrounded by asphalt and concrete, and generally isolated from the closest wetland — the Tukwila Pond. Wig qualifies for off -site mitigation under provisions b) and c). Table 1 demonstrates that the functional values of the Tukwila Pond site are significantly greater than the function values of the Penney site wetlands. Further, the Penney site wetland functions can be more than compensated for by converting degraded upland to wetland and enhancing degraded wetland on the Tukwila Pond site. Wetland functions currently present on the Mitigation site are projected to increase from the current rating of a Category Ill wetland to a Category II wetland by 2015. When considering wildlife habitat functions in isolation, the created and enhanced wetland (score = 70) is projected to out perform the existing wetland (score = 15) as well as the Penney site wetlands (score = 42) (Table 5). Tukwila requires that off -site mitigation shall occur within the same watershed where the loss occurred. The Tukwila Pond site is located in the same basin as the Penney site and therefore meets this requirement. Finally, the regulation lists an order of preference for off site mitigation. The Tukwila Pond site contains existing degraded upland and wetland. Degraded upland areas are listed as the second and degraded wetlands the fourth preference for off site mitigation. All of the other sites considered but the unavailable Strander site fall into the third preference. These sites were deemed unsuitable because they were either too small or contained excess overburden. 5.2 Rationale for Choice The 24-acre Tukwila Pond site was selected because it is the only suitable area available in the drainage basin. Also, the degraded area of the Tukwila Pond site has been identified by Tukwila as an area suitable for enhancement. Tukwila owns the site. 5.2.1 Case Study A 6.3-acre monoculture of reed canarygrass in Auburn was converted to a wetland complex possessing open water, emergent, scrub -shrub, and forested wetland classes (Raedeke Associates, 2002). This wetland was identified by Ecology as an example of a successful reed canarygrass conversion project. C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.docl3 08/10/06 Chad Armour, LLC 45 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington 5.2.2 Projected Conditions of the Mitigation Site At the end of the 10-year monitoring period the monoculture of reed canarygrass currently present on the Tukwila Pond site is projected to have been transformed into a wetland complex composed of open water, emergent, scrub -shrub, and forested habitats. All three wetland functions will improve relative to existing conditions (Table 1). Similarly Wig projects that they will exceed the functions exhibited by the Tukwila Pond site as a whole (Appendix B). The improved Mitigation site is projected to enhance water quality and habitat functions largely by adding complexity and structure where little previously existed. The Mitigation site ten years after it is improved would rate at the high end of the Category II wetlands. As shown on Table 1 the restored wetland (Projected Mitigation site) scored higher than the Tukwila Pond site for habitat largely because of added complexity. The Projected Mitigation site will have more plant communities and habitat amenities as well as fewer weeds than the existing Tukwila Pond site. 5.3 Constraints It appears that potential constraints can be adequately mitigated. The 3.48 acre wetland will be designed so that seasonal flooding and near -surface groundwater will support and maintain wetland plant communities. It will be vegetated with native plants that typically tolerate temporary seasonal flooding during the dormant season. The plan includes removing reed canarygrass. If the grass were not treated it would create a maintenance challenge during the monitoring and maintenance period. Its seed will be distributed throughout much if not all of the Mitigation site during flood events. As such Wig will remove the reed canarygrass, including its stolon mat, at the time of site grading. The resultant bare soil will be revegetated with native plants. A robust monitoring and maintenance plan will limit invading weeds, including reed canarygrass. Tukwila will protect the Mitigation site in perpetuity. In the event Tukwila alters other parts of the Tukwila Pond site to enhance its water quality or to increase its capacity to store stormwater, a deed restriction or some other site development -limiting instrument will protect the enhanced wetland. 5.4 Goals and Objectives of the Mitigation Plan To meet Tukwila's no net loss of wetland functions requirement, Wig proposes to improve the functions of 3.48 acres of degraded wetland and upland on the Tukwila Pond site. 5.4.1 Goals The goal of the mitigation plan is to create 0.88 acre and enhance 2.6 acres of degraded lacustrine emergent and open water wetland habitat by converting it to a diverse wetland complex composed of four wetland classes. This action will considerably improve the habitat for indigenous and migratory wildlife. It will also increase the stormwater detention capacity of the Tukwila Pond. 5.4.2 Objectives Hydrology • Open Water Wetland — water at least 2 feet deep into the late growing season; C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.docl4 08/10/06 Chad Armour, LLC 46 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS • Existing Degraded Wetland — seasonally flooded with saturated soil within 12 inches of the ground surface into the late growing season; • Emergent Wetland — seasonally flooded with saturated soil within 12 inches of the ground surface into the late growing season; • Scrub -shrub Wetland — seasonally flooded with saturated soil within 12 inches of the ground surface into the middle of the growing season; and • Forested Wetland — saturated soils within 12 inches of the ground surface in the early growing season. Wetland Classes • Open Water — occupy approximately 0.92 acre; • Existing Degraded Wetland — occupy approximately 0.88 acre and contain at least 3 native plant species (Table 6); • Emergent — occupy approximately 0.52 acre and contain at least 3 native plant species; • Scrub -shrub — occupy approximately 0.51 acres and contain at least 2 native plant species; and • Forested — occupy approximately 0.65 acre and contain at least 2 native plant species. Habitat Attributes • 6 hardwood snags ranging from 10 to 30 feet tall and 6 to 12 inches in diameter; and • 12 hardwood logs ranging from 10 to 30 feet long and 6 to 12 inches in diameter. 5.5 Performance Standards Performance standards provide a basis for measuring the success of the mitigation plan. The target for meeting the performance standards is within 10 years of installation. Comparing actual results of the interim monitoring events (i.e., Years 1, 2, 3, 4, 5, 7, and 9) with the performance standards will determine whether contingency actions are warranted. The following standards will apply. 5.5.1 Hydrology • Open Water Wetland — 0.92 acre of open water from 0 to more than 7 feet deep (constructed bottom 15.2 feet elevation) November through May; • Existing Degraded Wetland — 0.88 acre of emergent wetland with saturated soil between 17.7 and 20.0 feet elevation November through June; • Emergent Wetland — 0.52 acre of emergent wetland with saturated soil between 17.2 and 17.7 feet elevation November through June; • Scrub -shrub Wetland — 0.51 acres of scrub -shrub wetland with saturated soil between 17.7 and 18.2 feet elevation November through May; and • Forested Wetland — 0.65 acre of forested wetland with saturated soil between18.2 and 19.2 feet elevation November through April. C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.docl5 08/10/06 Chad Armour, LLC 47 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington 5.5.2 Soil At final grade, the upper 6 inches of soil will contain 20 to 25 percent organic matter, as validated by an approved agricultural testing laboratory. This requirement will be reflected in final plan specifications. 5.5.3 Vegetation • Emergent Wetland — 0.52 acre of emergent wetland that contains at least 3 or more native emergent plant species each consisting of at least 20 percent of total native emergent plant cover. The total native emergent plant cover will be at least: • 5%inYear 1, • 25% in Year 2, • 30% in Year 3, • 40% in Year 4, • 50% in Year 5, • 70% in Year 7, • 80% in Year 9, and • 90% in Year 10. • Existing Degraded Wetland — 0.88 acre of emergent wetland that contains at least 3 or more native emergent plant species each consisting of at least 20 percent of total native emergent plant cover. The total native emergent plant cover will be at least: • 5%inYear 1, • 25% in Year 2, • 30% in Year 3, • 40% in Year 4, • 50% in Year 5, • 70% in Year 7, • 80% in Year 9, and • 90% in Year 10. • Scrub -shrub Wetland — 0.51 acres of scrub -shrub wetland that contains at least 2 or more native shrub plant species each consisting of at least 20 percent of total native shrub plant cover. The total native shrub plant cover will be at least: • 5%inYear 1, • 20% in Year 2, • 30% in Year 3, • 40% in Year 4, • 50% in Year 5, • 70% in Year 7, C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.docl6 08/10/06 Chad Armour, LLC 48 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington • 80% in Year 9, and • 90% in Year 10. • Forested Wetland — 0.65 acre of forested wetland that contains at least 2 or more native tree plant species each consisting of at least 20 percent of total native tree plant cover. The total native tree plant cover will be at least: • 5%inYear 1, • 10% in Year 2, • 15% in Year 3, • 20% in Year 4, • 30% in Year 5, • 70% in Year 7, • 80% in Year 9, and • 90% in Year 10; and • No more than 20 percent of the vegetation will consist of non-native invasive plant species at any time during the monitoring period. This includes Himalayan blackberry, reed canarygrass, purple loosestrife (Lythrum salicaria), and all other Class A, B, and C weeds on the state noxious weed list. 5.5.4 Structure • Emergent Wetland — vegetation ranging from 1 to 4 feet tall by Year 3; • Existing Degraded Wetland — vegetation ranging from 1 to 2 feet tall by Year 3; • Scrub -shrub Wetland — vegetation ranging from 4 to 8 feet tall by Year 5; and • Forested Wetland — vegetation ranging from 8 to 20 feet tall by Year 7. 6. CONSTRUCTION PLAN This section of the plan describes the strategies that will be used to achieve the objectives described in Section 5.4.2. The plan is to remove all of the reed canarygrass and replace it with native trees, shrubs, and herbs adapted to seasonally flooded and saturated soil conditions. We reviewed the file, visited the site, and interviewed the designer of what appears to be a successful reed canarygrass conversion project in the City of Auburn. As indicated in Section 5.2.1, the 6-1--acre Goedeke wetland enhancement project was transformed from a monoculture of reed canarygrass to a diverse wetland composed of four wetland classes. To achieve this result, the reed canarygrass was mowed and the stolon mat was excavated, buried and covered with fabric and soil. In 2004 this precipitation driven wetland contained a wide variety of native trees, shrubs, and herbs, with very little reed canarygrass. Based on results of the Goedeke project, it appears that the reed canarygrass can successfully be converted to a wetland complex possessing increased water quality, hydrologic, and habitat values. C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.docl7 Chad Armour, LLC 08/1 0/06 49 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington 6.1 Hydrology Wig installed 14 shallow groundwater monitoring wells and 2 staff gauges in late 2004 to characterize the hydrology of the Mitigation site. Based on April measurements the central ridge of the Mitigation site is upland covering 0.88 acre (Figure 3). A significant portion of the area surrounding the upland is flooded in the winter and spring. The flooded area west of the upland drains slowly, presumably because the flap gate CMP is small relative the volume of water in the pond proper. We believe that the flooded area east of the upland drains more quickly because it represents a much smaller volume of water. 6.2 Soils Wig will grade the finished elevation of the Mitigation site according to the grading plan prepared by BRH (Figure 5). The grading plan is based on the results of the groundwater monitoring program during April 2005 & 2006. At a minimum, the upper ±6 inches of soil will be excavated and exported. Exporting the upper layer of soil removes the canarygrass' subsurface reproductive parts. More than a 6-inch-deep scoop will be required to eliminate reed canarygrass' subsurface reproductive parts on occasion. Wig will take every precaution to avoid or minimize impacts to existing stormwater control structures, including the flap gate CMP. If the flap gate and/or the associated berm are disturbed, Wig will repair these structures to Tukwila standards. We understand that the Tukwila Pond is considered a jurisdictional wetland by the Corps. As such a permit to export soil from the Mitigation site and if necessary import topsoil onto the same will require a permit from the Corps (Whiting, 2006). With respect to Wetland D on the Penney site, Wig must notify the Corps within 30 days after it is filled (Appendix A). Wig will match grades along the edge of the existing forested and scrub -shrub wetlands, the edge of the pond, and/or the upland buffers to the south and east. The slopes of the excavated channel will be nearly vertical. The intent is to encourage fish and wildlife that are attracted to open water to utilize these habitats and discourage emergent vegetation. Our hope is that the channel will promote water circulation from the Tukwila pond. The flow and the resultant mixing action could help improve the quality of the water in the Tukwila pond. To facilitate this flow, Wig will excavate the edge of the Tukwila pond at the entrance to the channels to match the bottom elevation of the channel. To augment the organic content of soils subject to excavation, Wig will rotovate three inches of fertile mulch (organic compost) into the upper 8 inches of the subgrade as necessary. 6.3 Vegetation As shown on Figure 6, at least four wetlands classes are proposed — open water, forested, scrub -shrub, and emergent. These new wetland classes will be juxtaposed with three existing wetland classes and two upland classes. The existing open water, scrub -shrub, and forested wetland classes and upland plant communities have been incorporated in the design to compliment the created/enhanced wetland area. Wig will vegetate the Mitigation site as indicated in Table 6. Several of the herbaceous plant species will be broadcast seeded throughout the emergent, scrub -shrub, and forested habitats. Larger herbs will be installed in the emergent wetland between 17.2 and 17.7 feet elevation. Selected herbs and the indicated shrubs will be installed in the scrub -shrub wetland between 17.7 and 18.2 feet elevation. The forested wetland will be vegetated with herbs, shrubs, and trees between 18.2 and 19.2 feet elevation. A mixture of grass species will be broadcast C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc18 08/10/06 Chad Armour, LLC 50 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS seeded throughout the Existing Degraded Wetland. The seed will be covered with about'/ inch of soil to minimize the potential for the seed to float away during subsequent flood events. Mulch will be placed around the base of all installed trees and shrubs for weed control and moisture retention in the spring after the threat of flood has past. Wig will install a temporary irrigation system designed to deliver up to 1 inch of water per week in the mitigation area for at least one growing season after the plants are installed. 6.4 Habitat Structures Wig will place 12 medium-sized (6 to 12 inches in diameter and 10 to 30 feet long) hardwood logs on the Mitigation site as habitat amenities. To reduce the potential for these logs to float away during anticipated periods of high water, Wig will anchor the logs to the ground. Wig will also install 6 hardwood snags — ranging from 10 to 30 feet tall and 6 to 12 inches in diameter on the Mitigation site. 6.5 Installation Sequence During a pre -construction meeting, the grading contractor, Wig, the project biologist, and appropriate regulatory agency staff will review the grading plan and best management practices (BMP), including stormwater pollution prevention plans (SWPPP), temporary erosion and sediment control plans (TESC), and spill control and prevention plans. In addition, components of the mitigation plan will be reviewed with the landscaping contractor at this meeting. Based on the outcome of the pre -construction meeting, the grading contractor will flag the construction limits consistent with the grading plan and BMPs, and will install temporary filter fabric fences as necessary. A temporary fence will also be installed between the construction area and the Sitka willow trees along the northwest boundary of the Mitigation site. Temporary fence will also be placed around existing clumps of red -osier dogwood shrubs along the southern Mitigation site boundary. Track hoe excavators, dump trucks, and/or dozers will be used to grade the Mitigation site. Machines will enter and leave the site via temporary construction entrances off Andover Parkway West. Because road drainage may contain soil and mud from construction vehicles and since the associated catch basins ultimately discharge to the Green River, filter fabric sediment traps will be installed and maintained at each catch basin. In addition, Andover will be swept as dirt or mud accumulates. Dust abatement measures, such as site watering during grading, will be instituted as necessary. As indicated previously, prior to site grading the reed canarygrass will be mowed and the cuttings will be disposed off site. Following mowing the reed canarygrass mat will be excavated and exported. If the results of the soil chemical analysis indicate that organic augmentation is warranted, approximately three inches of fertile organic mulch will be rotovated into the upper top 8 inches of soil. Next the contractors will install the habitat amenities, the temporary irrigation system, fence, sign, etc. In the spring after floodwaters have subsided, seed from residual weedy plants that likely are distributed over most of the Mitigation site will sprout. As such the landscaping contractor will likely have to treat the Mitigation site for weeds prior to planting. After the weeds are treated the landscaping contractor will broadcast seed the Mitigation site that is not designated open water C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.docl9 08/10/06 Chad Armour, LLC 51 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS habitat. About'/2 inch of soil will be raked over the seed. Landscapers walking all over the site will also help "set" the seed. Following seeding the landscaping contractor will install the plants specified on Table 6. Following construction and plant installation, the project biologist and landscaping contractor's representative will meet with Tukwila staff to develop a punch list of deficiencies. After the punch list items are addressed by Wig, Wig will seek approval for concluding the construction phase of the mitigation plan and seek Tukwila's approval to initiate the start of the ten-year monitoring period. Wig will develop an as -built plan that will be used as a basis for evaluating future results. 7. MONITORING PLAN The purpose of the monitoring plan is to assess the existing Mitigation site and the results of the mitigation measures. Monitoring the water regime prior to final design and construction increases the probability of success. Post -construction monitoring provides an index for measuring the performance of the mitigation plan, the extent and timing of remedial actions (if necessary), and ultimately the length of the monitoring period. The monitoring plan consists of three separate but equally important steps; pre -construction monitoring, construction monitoring, and post -construction monitoring. 7.1 Pre -Construction Monitoring Wig has been monitoring the hydrology of the Mitigation site since October 2004. 7.2 Construction Monitoring Wig will maintain quality assurance by monitoring grading and landscaping contractors during construction. This aspect of the monitoring plan is particularly important because the final design elevation of the wetland is critical to establish and maintain the appropriate wetland hydrology. Similarly the methods and techniques used to install the plants are important because in many cases survival is dependent on the quality of the installation. Tukwila will be responsible for final approval of construction. Wig will consult with Tukwila to assess deviations from the approved plan. After construction is completed, Tukwila will evaluate the installation and develop a punch list as necessary. Wig will address punch list items and prepare a post -installation report for review and approval by Tukwila. The post - installation report will be the basis for comparing future monitoring reports. 7.3 Post -Construction Monitoring Hydrology monitoring will commence immediately following construction to characterize the modified hydrologic conditions. The pre -construction shallow groundwater monitoring wells and staff gauges will be replaced and incorporated as part of the post -construction monitoring plan. Their position will be located by survey and shown on the As -Built Plan. Wig will monitor the mitigation area for 10 years following installation. A qualified biologist will be engaged for this effort. To document the results of the mitigation measures and to ensure that reed canarygrass and other incompatible weeds do not invade and take over the Mitigation site, Wig will monitor the Mitigation site annually for the first 5 years following installation as well as in Years 7, 9, and 10. Post -construction monitoring will include hydrology monitoring as well as vegetation monitoring. Wig will submit a detailed report comparing actual versus expected C:/JobsMfig/Revised Final Wetland Mitigation Plan.doc20 Chad Armour, LLC 08/10/06 52 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS performance standards to Tukwila for review and approval by December 31 each year the Mitigation site is monitored. 7.3.1 Hydrology Wig will measure the water levels at least four times a year (April, May, June, and August) during the growing season with an electronic water level meter. 7.3.2 Soils Wig will not monitor soils after post -installation sampling, provided that the performance standard is met at that time. 7.3.3 Vegetation To measure the success of the vegetation effort, Wig will install permanent photographic and vegetation monitoring points in the Mitigation site. The monitoring points will be established by installing a permanent structure such as rebar, wood, fence post, plastic pipe, etc. Wig will characterize the vegetation in August in 1/100-acre circular plots. The monitoring biologist will also informally assess the vegetation when on site to monitor hydrology. The intent of informal vegetation monitoring is to identify areas where undesirable weeds (e.g., reed canarygrass, purple loosestrife, etc.) are present. These observations will be relayed to the maintenance contractor for timely removal action. Photographs will be taken facing a predetermined direction for consistency to provide a visual record of the Mitigation site throughout the monitoring period. The vegetation monitoring will assess: • Species composition; • Percent cover of each plant stratum and species; • Stand height; and • The health of the vegetation. 7.3.4 Fauna Wig will record site observations of fish and wildlife during vegetation and groundwater monitoring activities. 7.3.5 Habitat Structures After the habitat amenities are installed and their location noted on the As -Built Plan, it will not likely be necessary to monitor them again. However, as indicated in Section 5.4.4, Wig will characterize the average height of the plants present in the emergent, scrub -shrub, and forested habitat types. Wildlife habitat is determined by the interspersion of plant communities, by the structure of the plant communities, and by the mixture of species within a community. Although all of these are important, most species of wildlife respond more to structure of the plant community than to the plant species making up a community (Hall, et al., 1985). 7.3.6 Water Quality Wig will not monitor water quality. 7.3.7 Buffers Wig will not monitor the buffers. C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc21 Chad Armour, LLC 08/10/06 53 Revised Final Wetland Mitigation Plan Wig Properties LLC-SS Tukwila, Washington 8. SITE PROTECTION To discourage human intrusion, a permanent post -and -rail fence at least 4 feet tall will be installed along the eastern boundary of the Mitigation site adjacent to Andover Parkway West. The eastern and southern perimeter of the Mitigation site will be posted with Habitat Conservation Area signs (Figure 6). Tukwila will be responsible for protecting the Mitigation site. In accordance with Section 18.48.090.0 of the sensitive areas regulations, the Mitigation site shall remain undeveloped and be protected from development in perpetuity. As such, Tukwila shall protect the Mitigation site via deed restriction, conservation easement, or other legally binding instrument. After Wig's monitoring and maintenance obligation is completed, the installed vegetation should be protected against any impacts from mowing, cutting, dredging, or other adverse activities to the Mitigation site. 9. MAINTENANCE PLAN Wig will maintain the Mitigation site during the 10-year monitoring period. Maintenance includes irrigating recently installed plants to promote their establishment and survival. One inch of water per week shall be applied to the Mitigation site from the time the plants are installed to mid - September the first year of plant installation. Irrigation is not required in subsequent years. Maintaining the Mitigation site is paramount to prevent unwanted plant species — particularly reed canarygrass and purple loosestrife — from expressing dominance during the 10-year monitoring period. Maintenance measures beyond the required monitoring period will become the responsibility of Tukwila. In addition to collecting hydrologic and vegetative data as specified in Section 7.3, the monitoring biologist will also note physical and biological features on the Mitigation site that need attention, are of note, or reflect the ecological health of the mitigation area. These features include, but are not necessarily limited to, wildlife use, trash, plant mortality, weeds, and predation by herbivores, etc. When reed canarygrass, purple loosestrife, or another aggressive undesirable weed is observed, Wig will instruct the maintenance contractor to treat the offending plants within 14 days. Manual weeding is the preferred method for removing the plants. However, on occasion it may be necessary to spot spray clumps with an approved herbicide. Rodeo is an herbicide approve for use in aquatic environments 10. CONTINGENCY PLAN Wig recognizes that there is a chance that some of the installed plants will not survive the seasonal flooding typical of the Tukwila pond. Wig also recognizes that seasonal flooding tends to favor reed canarygrass. To reduce these potentials Wig will: • Post a bond sufficient to cover the cost of replanting the Mitigation site; • Install plants that tolerate seasonal flooding during the dormant season; • Monitor the installed plants annually for the first 5 years; • Remove all reed canarygrass and purple loosestrife plants present on the Mitigation site; and • Install new plants annually to replace those that expired. C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc22 Chad Armour, LLC 08/10/06 54 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS 10.1 Post a Bond As indicated in Section 12, Wig will provide Tukwila with a surety instrument in the amount of 150 percent of the estimated cost to install plants on the mitigation site. 10.2 Install Plants Suited to Seasonal Flooding Wig will install plants native to Western Washington that are adapted to seasonal inundation during the winter rainy season. Many wetland plants survive seasonal inundation during the winter rainy season because these plants are dormant at the time of flooding. As indicated on Table 6 these plants include: • Trees - black cottonwood and Oregon ash (Fraxinus latifolia), and to a limited extent red alder (Alnus rubra); • Shrubs - Pacific willow, Piper's willow (Salix hookeriana), Sitka willow (Salix sitchensis), black twinberry (Lonicera involucrata), Pacific ninebark (Physocarpus capitatus), and red -osier dogwood; and • Herbs such as slough sedge (Carex obnupta), tufted hairgrass (Deschampsia cespitosa), common spike-rush (Eleocharis palustris), wool -grass (Scirpus cyperinus), and reed mannagrass (Glyceria grandis). The Mitigation site can be subject to flooding events during the rainy season. We observed inundation in both 2005 and 2006. The duration of these events can be as long as 4 months. The plants selected to replace reed canarygrass typically survive short -duration inundation during the winter rainy season when plants are typically dormant. 10.3 Annual Monitoring for the First 5 Years Plant succession on bare ground is fairly predictable. A number of weeds, including reed canarygrass, are expected to invade the bare areas initially. Bare areas are common on mitigation sites the first couple of years following plant installation. That is, bare soil is typical between installed trees and shrubs as well as locally where seeded grasses and herbs are removed by herbivory, flowing water, etc. To minimize the potential for reed canarygrass to become established in these bare areas, Wig will monitor the mitigation site several times a year (April, May, June, and August) during the first 5 years following plant installation. 10.4 Remove All Reed Canarygrass If reed canarygrass (and purple loosestrife) is observed during monitoring visits by the project biologist, its location will be marked in the field by the biologist. Initially, the biologist will accompany the maintenance contractor when they treat the offending plants to ensure that all of these plants are treated. Once the biologist feels comfortable with the maintenance contractor's ability to identify and treat offending weeds, it will no longer be necessary to accompany the maintenance contractor when weeds are observed. Wig will make every attempt to treat volunteer reed canarygrass plants before they go to seed. The entire plant, including stolons will be treated. This action will increase the potential that reed canarygrass plants represent a small fraction of the plant community. 10.5 Install Additional Plants as Necessary Typically 80 percent of the installed trees and shrubs survive installation. As such, Wig assumes that installing additional trees and shrubs and quite possibly herbs will be necessary near the end of the first growing season. If during subsequent years the monitoring biologist C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc23 Chad Armour, LLC 08/10/06 55 Revised Final Wetland Mitigation Plan Tukwila, Washington Wig Properties LLC-SS concludes that additional plantings are required, Wig will install additional plants as necessary. The selected replacement plants will include the most robust plant species growing on the site at the time of site evaluation. 11. SCHEDULE Wig anticipates executing the construction plan in 2007 and upon receipt of permits and/or approvals from Tukwila and/or Ecology. Site grading will be limited to the drier months when groundwater elevations are at their lowest. Wig anticipates installing the plant material the following spring after flood waters have subsided. It is important that the surface soil (i.e., upper 12 inches) is moist at the time of plant installation. Monitoring will commence immediately following acceptance of plant installation by Tukwila. 12. PERFORMANCE BOND Wig will post a bond or other surety in the amount of 150 percent of the value of the expected cost to install plants on the Mitigation site. 13. LIMITATIONS Work for this project was performed, and this plan prepared, in accordance with generally accepted professional practices for the nature and conditions of the work completed in the same or similar localities, at the time the work was performed. It is intended for the exclusive use of Wig Properties LLC-SS and its assigns for specific application to the referenced property. This plan is not meant to represent a legal opinion. No other warranty, express or implied, is made. It should be noted that Chad Armour, LLC relied on information provided by others indicated previously. Chad Armour can only relay this information and cannot be responsible for its accuracy or completeness. Also note that wetland mitigation planning is an inexact science. Biological professionals may disagree on the nature and extent of mitigation plans. Final acceptance of this wetland mitigation plan is the responsibility of the permitting authority. Accordingly, this wetland mitigation plan should be reviewed by the appropriate permitting authority prior to committing to detailed planning and design activities. C:/Jobs/Wig/Revised Final Wetland Mitigation Plan.doc24 Chad Armour, LLC 08/10/06 56 Chad Armour, LLC August 25, 2006 Moira Bradshaw, Senior Planner City of Tukwila Department of Community Development 6300 Southcenter Boulevard, Suite 100 Tukwila, Washington 98188-2544 Subject: Mitigation Plan Bond Southcenter Square Tukwila, Washington SEP 2 2 2006 i UKWIi A PUBLIC WORKS Dear Ms. Bradshaw: In your August 22, 2006 email you asked us to estimate the cost to construct and restore the wetland in the Tukwila Pond and to monitor and maintain it for 10 years, We trust that this information meets your needs. If you have any questions about the spreadsheet, please let us know. Sincerely, Chad Armour, LLC Chad Armour Principal Attachments: Attachment A — Bond Quantity Worksheet for the Tukwila Pond Wetland Restoration 6500 1261h Avenue SE Bellevue, Washington 98006 www.chadarmour.corn (425) 641-9743 (425) 643-3499 (Fax) chadSchadarmaur.com Pu1o6-gal 57 Bond Quantity Worksheet for Sensitive Area Mitigations Project Name: Southcef'ier Square Project Address: Tukwila Pond Wetland Restoration Wetland File No. 23-Aug-06 Contact Person/Phone: Chad Armour (425.641.9743) Date: Trees (includes delivery, installation, and materials) Scientific Name Common Name I Qty Unit Price 1 gallon Alnus rubra Fraxinus lataolia Pop:dustrichocarpa re• alder regon as lblack cottonotrd [Total $0.0 Qty Unit Price 2 gallon 2 gal i Qty Unit Price 1.5"* caap Total Ct Total I 1.5" cal Total a1. u 4 55 u I ,)> -,)8D 56. of 31 $ 55.00 $1,705 11,705 � OS $0.00 Total $0.00 Total $6,8751 S6,875 Shrubs (includes delivery, installation, and materials) Sclentintc Name Common Name I Qty Unit Price 1 gallon :era i Ira Pi a at Live Stakes / Cuttings Scientific Name Populus trichocarpa Salix lasiandra Salix pipers Salix sitchensis d-osier dogwood black twinberry Pacific ninebark Common Name ty otaI Unit Price Slack cortoraw Pacific willow Piper's willow Sitka willow 440 $2.00 1 gal Total au. 3.56 I a _t .uu ltu,a40 0- j au vu aau air. G.0ul 30 ) $ 30.00 I $900.00 ( I $0.0u $9a00 00 $1 00 OAQI$900 _ 30 I $ 30AG ' $9GU.OU1 i �, $0.00 i I $ii,94'O,tlil s0.001 Total I $11,940.001 'Total T sue, Cost Unit Qty Unit Price I 2 gal 2 gallon Total Total. Cos $0.00 5� 124 $2.00 $24 123 $2.001 Sub Total $1,374.00 Qty Unit Price 5 gal 5 gallon I Total Page 1 Bond Quantity Worksheet.xls 58 Earthwork/Organics (labor, equipment, overhead and profit) S , ecific Name I Unit Price Gradin Topsoil - delivered & spread Mulch 14.0 Unit 40 Amount 4, 0 Ttstal $3.00 4000 $12.951 1400 $20.001 681 4.000 1.400 681 12,000.,00 Sub Total Grasses/Emeraents (includes delivery, installation, and mater'als) Name Seeding Acre Unit Pounds Total Cost. Rate Price ,10 . 2..25 (land See cax, including: Beckmannia syzigachne Deschanapsio cespitosa flymus glaucres Giyseria occtdentalis Horde atm brachyantherum 2 to 40 lb./acre American sloughgrass tufted hairgrass blue wildrye western mannagrass meadow barley apvia cespitosa crop.k lure rra rarul s ufted hairgrass large -leaved avens reed mannagrass 1.68 $50.00; 0.55 1.68 S120.001 1.68 $100.00 5.9 $27.50 $120.00 $590.00 Sub Total 53,465.50 Specific Name Qty Unit Price br Total Cost Carex obnupta 'slough sedge 1 , Isawbeak sedge2 7436 $1.65 ' 1 x2,267.40' ,ar°ex stipata Bieachris ahastris [commonsppire-ntsb 1898 $1.65 1.31 40 5rirpus cyperinus Iwool-grass 950 $1.65 $1.56770 bcrrpars da2rerracrernarretarai (softstem bulrush 950 $1.65 $1„56+.50 $0.00 Sub Total $30,150.45 Page 2 111.30.00 1',620.00 S99,750,.00 Bond Quantity Worksheet.xls 59 Habitat Structures (includes delivery, installation, and materials) Specific Name Unit Price Wood debris, large Snags General Items (includes delivery, installation, and Specific Name Fencing, Split Rail, 4' High (3-rail) or 3' High C2-rail)'' Signs, Sensitive Area Boundary Irrigation, Temporary s350.00 1 S500.001 12 0 Sub Total $7,200.00 materials) Unit Cost ! Units 1 I $10.001 8b0 I 320.001 12 1 S9,500.001 I Sub Total ** may be included in construction bond instead of wetland bond with City approval Monitoring and Maintenance Costs tenance - next 8 ye,ats Monitoring attnnuta1- 1st 5 years Monitoring annual - Year 7 Monitoring annual - Years 9 & 10 O Unit Price(' Unit 1 LI I I 8 I 5,650.001 L 5 2,500.001 1 I 3,000.001 1 2 I 3,500.001 Sub Total Total Construction/Maintenance/Monitoring Costs Total Bond Amount Agency Multiplier 150% I Cast 6,000 Off $240.00 ,500.00 S15,740.00 Total Cost — $26,366.004 S45,200.00 S12,500 00 0.00 $7 S94,066.00 $26.9,186, 95 $4 9,43 • Page 3 Bond Quantity Worksheet.xls 60 6500 128a" Avenue S.E. elievue, 'Washington 98006-39411 (425p 841 9"743 Office (425) 43•34 99 Fax chadir archadarmour.com August 13, 2010 Job No. 08-002 Ms. Anjali Wig Wig Properties LLC-SS 4811 — 134mh Lace SE. Bellevue, Washington 98006 Subject: Third Year Wetland Mitigation Monitoring Report Tukwila Pond Mitigation Area (Fed Ref No. 200601027; St Ref No. 3815) Tukwila, Washington Dear Ms. Wig: We are pleased to present the results of our wetland mitigation monitoring report the third year after installing plants on the above -referenced property. This is the third of several monitoring reports to assess the condition of the mitigation area relative to the performance standards. The purpose of the work is to satisfy federal, state, and local wetland permit requirements. The report is organized in sections and includes: SUMMARY OF FINDINGS that presents the results of the third year of monitoring and recommendations for additional work; BACKGROUND INFORMATION that explains the purpose for the mitigation and how the mitigation area came to be; MONITORING METHODS that describes how we collected the data, and presents the goals and performance standards of the mitigation plan; MITIGATION AREA OBSERVATIONS that presents the results of our current hydrological and vegetative observations; CONCLUSIONS that summarize the results of wetland mitigation to date relative to the performance standards; and LIMITATIONS of this project. Tables, figures, and representative photographs follow the text of the report. Table 1 shows the precipitation that fell on the region in the 2009/2010 water year. Table 2 presents the hydrological data for the mitigation area. Table 3 presents the vegetative data for the various wetland classes. And finally Table 4 summarizes the current vegetative data relative to the performance standards. Figure 1 is a vicinity map that shows the location of the mitigation area. Figure 2 shows the location of the vegetation classes, monitoring wells, and other pertinent features, as well as the size of the wetland classes and the plants that were installed on the mitigation area. Representative photographs follow the figures. C:/Jobs/Wig/3rd Year Mitigation Report.doc 1 08/13/10 Chad Armour, LLC 61 Third Annual Wetland Mitigation Monitoring Tukwila Pond Mitigation Site Tukwila, Washington SUMMARY OF FINDINGS Wig Properties, LLC-SS (Wig) converted the area east of the Tukwila Pond from a wetland and upland plant community dominated by reed canarygrass to a wetland plant community containing four wetland classes — open water, emergent, scrub -shrub, and forested. During the grading operation Wig was able to retain a significant portion of the mature trees and shrubs present in and adjacent to the mitigation area (site). Soon after the site was graded Wig installed several thousand native trees, shrubs, and herbaceous plants. Wig also applied the seed of several different grasses and herbs to the site. Chad Armour, LLC (Armour) collected groundwater data from several shallow groundwater monitoring wells several times in the spring and summer and collected vegetative data in the summer of 2010. The results of the third year of monitoring indicate that the site is in the process of complying with the performance standards. It appears that wetland hydrology is present throughout most of the site. The monitoring well measurements that are out of compliance appear to be related to excess ground elevation. Most of the vegetative performance standards are in compliance at this time. Currently the dominant plant species include Pacific willow, Sitka willow, red -osier dogwood, and tufted hairgrass. We observed less than 1 % cover of non-native invasive plant species. Recommendations We recommend that Wig continue to aggressively treat non-native invasive plant species, particularly reed canarygrass and purple loosestrife. The reed canarygrass and purple loosestrife should be removed from the ground, roots and all and disposed off of the site. However; the reed canarygrass is prevalent enough that the clumps can be sprayed with an approved herbicide. Install up to 25 Oregon ash trees in the forested wetland near where red alder and/or black cottonwood trees have died. Installing `large' trees is not beneficial. Rather the new trees should be of the 5-gallon variety. Fit the existing `large' trees and the 25 trees to be installed with tree trunk protectors. The tree trunk protectors will make it difficult for rodents to access the bark of these trees. It will be necessary to remove the grass before the protectors are installed. Remove the wooden stakes that were installed to support the `large' trees. These trees no longer need the support. Remove any remaining irrigation pipe on the site. BACKGROUND INFORMATION Wig constructed a wetland and enhanced degraded wetland in 2007 to compensate for filling slightly less than 1.16 acres (ac) of wetland on their Tukwila Southcenter shopping center. The 3.48ac site is a part of a larger 24-ac Tukwila Pond property that includes the pond and what was once a field of reed canarygrass, both with fringes of willow and/or black cottonwood trees. The site is located west of Andover Parkway West about 600 feet (ft) south of the intersection of Strander Boulevard and Andover Parkway West in Tukwila Washington (Figure 1 — Tukwila Pond Site). C:/Jobs/Wig/3rd Year Mitigation Report.doc 2 08/13/10 Chad Armour, LLC 62 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site Upland was transformed to wetland and degraded wetland was improved by replacing non-native invasives with a native plant assemblage. First Wig mowed the reed canarygrass then removed its rhizome mat before hauling it from the site. Then they removed some soil from the site, bringing the surface closer to the seasonal water table. To boost post -grading soil productivity, Wig mixed 3 inches (in) of Steergrow, a top soil substitute, into the upper layer of soil. They then installed several snags and added several pieces of large woody debris (LWD) to the finished surface prior to installing the plants. At the time the mitigation area was graded, Wig made every effort to avoid cutting down existing mature trees and shrubs. The net result is more forested wetland and less emergent wetland that planned. The City of Tukwila (City) was concerned that the Steergrow (50% steer manure and 50% sawdust) would negatively impact the water quality of the Tukwila Pond. For this reason the City asked Wig to bridge the open water channel to prevent the water in the channel from mixing with the water in the pond. The sand dike at the south end of the channel has been breached and water from the pond has been comingling with water in the channel for the last two rainy seasons. Wig also added a berm adjacent to the northwest edge of the mitigation area. Following grading, Wig installed several thousand trees and shrubs. Wig also installed several thousand sedge, rush, and spike-rush plugs as well as a mixture of emergent plant seeds to the bare soil. The plan was to install plugs and seeds differentially among wetland classes. During installation the plugs and seeds were installed across the entire wetland mitigation area. Prior to construction Armour installed 17 shallow groundwater monitoring wells (wells) made from plastic PVC pipe across the site to model the groundwater elevation (Figure 2). Ten of these wells survived site grading. The seven new wells replace those lost during site grading. Together they completely cover the site. The wells serve as the centers of 13 circular 1/100 acre vegetation assessment plots. After the first years monitoring we noticed that some wells yielded plots that straddled vegetative classes (i.e., emergent and forested). In other areas large branches of willows fell into plots, causing an emergent class to look like a forested class. For these reasons we moved five of the vegetative plots about 20 to 75ft from the similarly numbered well. For the past two years Wig has maintained the site by removing non-native noxious weeds. Weeds removed and/or treated include Himalayan blackberry, reed canarygrass, and purple loose -strife. In 2008 Wig installed about 80 additional willow live stakes on the site to replace those that had died. MONITORING METHODS Armour used an electronic water level indicator to detect ground and/or surface water in each of the 17 wells five times (March, April, May, June, and August). These measurements allow us to calculate the elevation of the groundwater or surface water. Groundwater elevation can be used as a surrogate to infer surface soil saturation. In this instance we assume that wetland hydrology is present if groundwater is within 1ft of C:/Jobs/Wig/3rd Year Mitigation Report.doc Chad Armour, LLC 3 08/13/10 63 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site the surface or the surface soil is saturated. We record the data in the field and transfer it to a spreadsheet that calculated the ground and/or surface water elevation. In each vegetative plot we note the health, estimated the cover of the trees, shrubs, herbs, and undesirable plants by species, and estimated the height of the vegetation. We designed the performance standards to evaluate short-, mid-, and long-term vegetation targets. Armour assessed the vegetation on August 11, 2010; recording the data in the field and transferring the data to an electronic spreadsheet for analysis. Goal The goal of the mitigation plan is to create 0.88ac and enhance 2.6ac of degraded lacustrine emergent and open water wetland habitat by converting it to a diverse wetland complex composed of four wetland classes. This action will considerably improve the habitat for indigenous and migratory wildlife. It will also increase the stormwater detention capacity of the Tukwila Pond. Performance Standards Hydrology Performance Standards The design performance standards used to assess wetland hydrology include: • Open water wetland — water from 0 to more than 7ft deep November through May; • Emergent wetland — saturated soil between 17.2 and 17.7ft elevation November through June (the hydrology performance standard for the existing degraded wetland [now folded into the emergent wetland] ranged from 17.7 to 20.0ft); • Scrub -shrub wetland — saturated soil between 17.7 and 18.2ft elevation November through May; and • Forested wetland — saturated soil between 18.2 and 19.2ft elevation November through April. Vegetation Performance Standards The vegetation performance standards include: • Emergent wetland — at least 3 or more native emergent plant species each consisting of at least 20% of total native emergent plant cover and ranging from 1 to 4 ft tall at the end of the 1-year monitoring effort; • Scrub -shrub wetland — at least 2 or more native shrub plant species each consisting of at least 20% of total native shrub plant cover and ranging from 4 to 8 ft tall at the end of the 1-year monitoring effort; • Forested wetland — at least 2 or more native tree plant species each consisting of at least 20% of total native tree plant cover and ranging from 8 to 20ft tall at the end of the 1-year monitoring effort; • The total native plant cover for each wetland class in Year 3 will be at least: • Emergent — 30%, • Scrub -Shrub — 30%, C:/Jobs/Wig/3`d Year Mitigation Report.doc 4 08/13/10 Chad Armour, LLC 64 Third Annual Wetland Mitigation Monitoring Tukwila Pond Mitigation Site Tukwila, Washington • Forested — 15%, and • No more than 20% of the vegetation will consist of non-native invasive plant species at any time during the monitoring period. MITIGATION AREA OBSERVATIONS The 2009/2010 water year was wetter than normal. Excess precipitation for the 6 'wet' months ranged from 21 % to 73% of normal. The two 'dry' months — November and February — were 51 % and 16% drier than normal. A normal amount of precipitation fell in March (Table 1). Much of the wetland was flooded for a significant period. The open water channel was flooded a month longer than it was in 2009. Water was somewhat more than a foot deep in mid -August (Table 2). Parts of the emergent, scrub -shrub, and forested wetland classes were flooded though the end of June. Other areas were flooded though May. Wetland hydrology was consistently present through the target date for the existing forested and open water wetlands. Depending on the elevation of the ground, wetland hydrology was either present or absent through the target date in parts of the scrub - shrub and emergent wetlands. The total cover of installed, volunteer and non-native plant species ranged from 3 to 197% (Table 3). As expected plant cover in the open water wetland was negligible, although in some areas grasses and herbs adapted to prolonged flooding in shallow water are colonizing the channel. About half of the plant cover in the emergent wetland is represented by tree seedlings. Similarly, nearly half the cover in the scrub -shrub wetland is represented by tree seedlings. Willow is aggressively colonizing that part of the mitigation area that is regularly flooded. Trees represent nearly half of the cover in the forested wetland. As expected, trees represent most of the cover in the existing forest. Table 4 shows the vegetative results relative to the performance standards. To date Wig has met all but two of the vegetative standards. Only one dominant is present in the emergent wetland (three are required) and the average height of the vegetation on the forested wetland is less than the 20ft requirement. The following paragraphs summarize our observations based on the data collected in 2010 by wetland class. Emergent Wetland Based on the 2010 hydrology data for the emergent wetland it would appear that wetland hydrology met the performance target in three of the four wells (Table 2). Two of the areas as represented by wells G-103 & G-7 were flooded through the end of June. The groundwater in the area represented by well G-106 was below or at the target elevation through the end of June; however, we never observe surface soil saturation at this location. Well G-101 missed the target significantly. Here groundwater ranged from 1.1 to 1.5ft below the target elevation from the end of March through the end of June. The area represented by well G-101 does not meet the regulatory wetland hydrology requirement of being inundated or saturated to the surface for more than 30 consecutive days. The emergent wetland in the northeast corner of the site is dominated by herbs and tree seedlings, including tufted hairgrass, creeping buttercup, and black cottonwood. Other 5 08/13/10 C:/Jobs/Wig/3`d Year Mitigation Report.doc Chad Armour, LLC 65 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site common plant species include bulrush, soft rush, and Pacific willow (Attachment A — Photograph 1). The emergent wetland in the southwest corner of the site is dominated by creeping buttercup, black cottonwood, and Pacific willow. Soft rush and western yellowcress are common (Photograph 2). Branches of willow trees have fallen into the emergent wetland from the adjacent willow forest at a number of spots. The black cottonwood and willow seedling that form a virtual carpet in areas of prolonged flooding suggest that these parts of the emergent wetland will eventually become forested wetland. There are a total of 25 different plant species in the emergent wetland. The native plant species cover 96% of the emergent wetland; far more than the 30% Year 3 cover standard (Table 4). The dominant plant species — black cottonwood and Pacific willow seedlings — represent more than half of the total vegetative cover. Less than 1% of the cover is attributable to non-native invasive plant species (Table 3). Scrub -Shrub Wetland Two of the three wells in the scrub -shrub wetland met the hydrology performance target (Table 2). One area was flooded through the end of June; the other area was flooded through the beginning of June. From a regulatory perspective the areas represented by all three wells exhibited wetland hydrology because the soil was saturated to the surface for at least 30 consecutive days during the growing season. From the performance standard perspective the area in the vicinity of well G-105 missed the hydrology target. We counted a total of 17 plant species in the scrub -shrub wetland (Table 3). The total native plant cover (110%) far exceeds the 30% Year 3 cover standard (Table 4). The areas that are regularly flooded (G-8 & G-109) are dominated by Sitka willow saplings, Pacific willow seedlings, and soft rush. Black cottonwood saplings and spotted ladysthumb are common (Photographs 3 & 4). The non -flooded shrub -shrub wetland is dominated by red -osier dogwood and tufted hairgrass. Hooker willow saplings are common (Photograph 5). We observed only a trace of non-native invasive plants in this wetland class. Forested Wetland Both of the wells in the forested wetland met the hydrology performance target (Table 2). They also met the regulatory hydrology requirement. The forested wetland is covered with a thick blanket of vegetation (Photograph 6). We counted 14 different plant species (Table 3). The 102% cover of native plants far exceeds the 15% Year 3 cover standard (Table 4). Pacific willow, red -osier dogwood, American sloughgrass, tufted hairgrass, and creeping buttercup dominate. Climbing nightshade is common in the forested wetland. We observed only a trace of non-native invasive plants in this wetland class. In late April we observe that several of the installed trees appear to be dying. On closer inspection we saw that several black cottonwood and red alder trees are rooted in standing water during the early growing season. Both of these tree species are adapted to mesic (i.e., moderate) water regimes, but not hydric (i.e., flooded are prolonged surface soil saturation) water regimes. In August we counted 11 dead red alder trees and 9 black cottonwood trees. It is entirely possible that additional red alder trees will expire in the next year or so due to prolonged flooding during the early growing season. C:/Jobs/Wig/3rd Year Mitigation Report.doc 6 08/13/10 Chad Armour, LLC 66 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site Although the outer bark of the Oregon ash trees has been gnawed by small rodents, none of these threes are dead. They are adapted to wetter soil conditions than are the alder and cottonwood. Open Water Wetland The hydrology performance standard for the open water wetland was achieved in 2010. This wetland class was flooded through the middle of August with nearly 1.5ft of water (Table 2). Near the end of the second growing season the open water wetland continues to be sparsely vegetated. The presence of standing water limits the vegetation in this wetland class. We observed 2 different plant species that cover 3% of the area (Table 3). Although not rooted in the open water wetland willow branches overhang the channel in places (Photograph 7). In other places aquatic vegetation is beginning to colonize the more protected areas (Photograph 8). We observed no non-native invasive plant species in the open water wetland. Existing Forested Wetland Wetland hydrology for the existing forested wetland was present through the end of June (Table 2). Three of our original wells are located in existing forested areas dominated by Pacific willow trees ranging from 45 to 50ft tall. The total vegetative cover for the existing forested wetland is 197%, with trees representing 130%, shrubs 3%, and herbs 33% of the cover, respectively (Table 3). In addition to Pacific willow, dominant plant species include Sitka willow, creeping buttercup, and Watson willow -herb. Grasses are common volunteers. We observed only a trace of non-native invasive plants in this wetland class. CONCLUSIONS The wetland mitigation plan for the Tukwila Pond site currently appears to be on track. Hydrology With a few possible exceptions it appears that wetland hydrology in the created and enhanced wetlands is present. After three years of monitoring it appears that one area — the area represented by well G-101 — may not meet the hydrology performance standard. This area has consistently been 'dry' since the wetland was created/enhanced. A hydrological snapshot of this area in early April 2005 and mid -April 2006 prior to creation/enhancement indicates that this area functioned as upland prior to grading. At that time depth to groundwater ranged from 2.3 to 4.1ft below the ground surface. Other areas not a part of the open water wetland is wetter than planned. These areas are subject to prolonged seasonal flooding and are represented by wells G-103 & G-7 (emergent wetland), G-8 & G-109 (scrub -shrub wetland), and G-113 (forested wetland). All of these areas are adjacent to the open water wetland and are in the process of being dominated by Pacific willow. C:/Jobs/Wig/3rd Year Mitigation Report.doc 7 08/13/10 Chad Armour, LLC 67 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site Vegetation Wig is on track to meet the vegetative performance standards. Many of the cover and height requirements have been met (Table 4). Although the data does not show it, we observe considerably more non-native invasives on the site, particularly reed canarygrass and purple loosestrife. What were once small clumps are now small patches of reed canarygrass. Purple loosestrife has spread beyond the western edge of the Pacific willow forest. It is now also present along the edge of the open water wetland in the northeastern sector of the wetland. LIMITATIONS Work for this project was performed, and this letter report prepared, in accordance with generally accepted professional practices for the nature and conditions of the work completed in the same or similar localities, at the time the work was performed. It is intended for the exclusive use of Wig Properties LLC-SS and their assigns for specific application to the referenced property. This report is not meant to represent a legal opinion. No other warranty, express or implied, is made. Any questions regarding our work and this report, the presentation of the information, and the interpretation of the data are welcome and should be referred to the undersigned. Sincerely, Chad Armour, LLC Chad Armour Principal Table 1 — Precipitation measured at SeaTac from October 2009 through June 2010 Table 2 — Third Year (2010) subsurface hydrologic characteristics on the mitigation site Table 3 — Third Year (2010) vegetation characteristics on the mitigation site Table 4 — Third Year (2010) performance standard assessment for the mitigation site Figure 1 — Vicinity Map Figure 2 — Post -Construction Plan Attachment A — Representative Photographs cc: Sandra Whiting, City of Tukwila Amy Klein, U.S. Army Corps of Engineers Patrick McGraner, Department of Ecology C:/Jobs/Wig/3rd Year Mitigation Report.doc 8 08/13/10 Chad Armour, LLC 68 TABLES 69 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site Table 1 - Precipitation measure at SeaTac from October 2008 through June 2009 Month October November December January February March April Measured Normal 5.54 3.19 8.96 2.75 6.17 3.52 5.9 5.62 5.13 4.18 1.04 -0.66 3.76 3.75 0.01 Cumulative Departure 2.35 5.41 2.54 3.58 2.92 2.93 May June 3.49 2. 59 0.90 2.83 1.78 ........ 1.05 2.49 1.49 1.00 3.83 4.88 5.88 C:/Jobs/Wig/3rd Year Mitigation Report .doc 08/12/10 Chad Armour, LLC 70 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site Table 2 - Third Year (2010) hydrologic characteristics on the Tukwila Pond Groundwater Monitoring Well Habitat T pe Ground l Elev ft Target Elev ft NA (17.7)c 3/31/10 Groundwater Elevation 4/27/10 s 6/1/10 18.75f 1 18.559 ft)a 6/30/10 18.44g 8/11/210 16.6 G-2b Forested Wetland (ex) 18.7 18.88f G-4b Forested Wetland (ex) 18.5 NA (17.5)c 18.83f 18.68f 18.519 18.429 17.2 G-11 b Forested Wetland (ex) 13.5 NA (12.5)c 18.82ef 18.71 of 18.54ef 18.5ef 16.48ef =' G-7 Emergent Wetland 17.6 16.6c 18.79f 18.76f 18.52f 18.42f 17.38g G-101 Emergent Wetland 19.4 18.4c 17.0 17.2 16.9 14.3 G-103 E Emergent Wetland 18.0 17.0c 18.51 f 18.69f 18.49f 18.41 f 14.4 G-106 Emergent Wetland 19.2 18.2c 18.7 18.7 18.4 18.2 16.3 G-8 Scrub -Shrub Wetland 18.5 17.5c 18.82f 18.68f 18.52f 18.4 16.4 G-105 Scrub -Shrub Wetland 18.9 17.9c 17.92g 17.2 16.6 16.5 14.4 G-109 Scrub -Shrub Wetland 17.8 16.8c 18.77f 18.67f 18.49f 18.39f 15.7 G-113 Forested Wetland 18.0 17.0c 18.84f 18.73f 18.54f = 18.47f 14.8 G-115 Forested Wetland 18.9 17.9c 18.79g 18.72g 18.5g 17.4 _ 15.0 G-10 Open Water Wetland 15.0 15.2d 18.8f 18.74f 18.56f 18.49f 16.49f G-12 Open Water Wetland 15.0 15.2d 18.83ef 18.71 of 18.54ef 18.5ef 17.13f G-14 Open Water Wetland 15.0 15.2d 18.92f 18.75f 18.55f 18.5f 16.52f S-1 Open Water Wetland 15.1 15.2d 18.87f 18.74f 18.56f 18.47f 16.48f S-2h O Open Water Wetland 18.7 15.2d 18.84f 18.73f 18.5 1 18.45g 15.7 a Emergent target through June; Scrub -Shrub target through May; Forested target through April; & Open Water target through May b control - for comparison only; ° 1 ft below the ground elevation d the design elevation e estimated elevation based on elevations from nearby monitoring wells f flooded; g soil saturated to the surface; h located on the northern dike shaded numbers indicate that the target elevation was not met and wetland hydrology is not sent C:/Jobs/Wig/3`d Year Mitigation Report .doc Chad Armour, LLC 08/12/10 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site Table 3 - Third Year (2010) vegetation characteristics on the Tukwila Pond mitigation site Open Water Wetlands Emergent Wetlandb Scrub -Shrub Wetlands Forested Wetland` Forested Wetland (Ex)a Cover Freq Cover Freq Cover Fre • Cover 1 Freq Cover I Fre • black cottonwood Populus balsamifera Trees -- -- 18% 50% 6% 100% -- -- -- -- Pacific willow Salix lasiandra -- -- 37% 75% 16% 100% 52% 100% 90% 100% red alder Alnus rubra -- -- 1.1111.IIIIII -- -- 8% 50% Sitka willow Salix sitchensis -- -- 4% 50% 28% 67% _ -- -- 40% 67% Total Trees 0% 55% 1 Shrubs 50% 60% 130% Hooker's willow ll Salix hookeriana -- i -- 5% 33% _ 3% 50% -- red elderberry red -osier dogwood Sambucus ' racemosa -- -- Cornus stolonifera -- -- T 25% -- T 50% 10% 100% 67% 20% 100% 3% Rubus thimbleber parviflorus -- -- T 25% -- 1111 -- Native Shrub Subtotal 0% -- T -- 10% -- 23% -- 3% Himalayan blackberry Rubus discolor -- -- T 50% -- -- -- T 1 33% Non -Native Invasive Shrub Subtotal 0% T -- ? 0% 0% ° Total Shrubs 0% T 10% 23% 3% Herbs American slou • .rass Beckmannia syzi. achne -- -- T 25% -- -- 10% 50% -- -- American waterplantain Alisma plantago- aquatica T 33% -- -- -- -- -- -- -- -- C:/Jobs/Wig/3rd Year Mitigation Report .doc Chad Armour, LLC 08/12/10 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site Table 3 - Third Year (2010) vegetation characteristics on the Tukwila Pond miti� bulrush Scirpus acutus -- -- 4% 25% -- -- -- -- -- climbing ni•htshaded Solanum dulcamara -- 3% 50% -- -- 8% 50% T 67% common spike-rush Eleocharis1111 palustris -- T 33% -- -- --- -- -- common cattail T pha latifolia -- -- T 25% -- creeping buttercups Ranunculus . repens -- -- 11% 50% T 33% -- -- 27% 67% unidentified rasses -- -- -- -- T 33% 10% 1 50% 5% 33% large -leaved avens g Geum , macrophyllum -- 2% 50%-- -- T 50% -- -- mint Mentha sp. -- -- -- T 33% -- -- -- -- prostrate knotweed Polygonum aviculare 3% 33% 1 % 25% -- -- -- -- -- -- slough sedge Carex obnupta T 25% -- -- T 100% ' -- -- soft rush Juncus effusus -- -- 6% 75% 7% 33% 4% 100% 2% 33% spatter -dock Nuphar lutem -- -- ® -- -- 10% 33% spotted ladysthumb Polygonum = persicaria -- -- 1% 25% 3% 33% -- thick-headed sedge Carex pachystach a -- -- T 25% 2% 33% T 50% ---- three -square bulrush Scirpus americana T T 25% -- -- -- -- tufted hairgrass Deschampsia cespitosa -- -- 16% 75% 33% 33% 10% 100% -- -- Watson willowherb Epilobium watsonii -- -- 2% 50% T 33% 3% 50% 20% 67% western yellowcress Rorippa curvisiliqua 3% 25% 2% 67% white clovers Trifolium re.ens ° -- -- -- -- T 3 33% C:/Jobs/Wig/3`d Year Mitigation Report .doc Chad Armour, LLC 08/12/10 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site Table 3 - Third Year (2010) vegetation characteristics on the Tukwila Pond mitigation site wool -grass Scirpus cyperinus -- -- 2% 25% -- -- yellow iris Iris pseudacorus -- -- -- -- T 33% -- -- -- -- Native Herbs Subtotal 3% -- 51% -- 47% -- 45% -- 64% -- purple loosestrife Lythrum salicaria -- -- T 25% -- -- -- -- T I 33% reed canarygrass Phalaris arundinacea -- -- T 25% T 33% T 50% T 33% Non -Native Invasive Herbs Subtotal 0% -- T -- T -- T -- T -- Total Herbs 3% 51% 53% 45% ? 64% Total Cover 3% 106% 113% 128% 197% a 3 plots; b 4 plots; ° 2 plots; d non-native; T trace C:/Jobs/Wig/3rd Year Mitigation Report .doc 08/12/10 Chad Armour, LLC Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site Table 4 - Third Year (2010) performance standard assessment for the Tukwila Pond mitigation site Performance Standard Cover of native dominantsa Dominant Plant S•ecies Pacific willow Plant Association Emer•ent 1 Scrub -Shrub Forested 52%0 -- 37% 16% 4% 28% Sitka willow red-osier dogwood T 10% 20% tufted hairgrass 16% 33% 10% Total native plant coverb 96% 110% 102% Non-native invasive coverc T T T Average plant heights 3.6ft 6.1ft 4.6ft a Year 10 standard - 20% cover for 3 species (Emergent) & 20% cover for 2 species (Scrub -shrub & Forested) b Year 3 standard - Emergent 30%, Scrub -shrub 30%, Forested 15% ° Standard <20% s 1-4 ft (EM) Year 3 Standard, 4-8 ft (SS) Year 5 Standard, & 8-20 ft (FO) Year 7 Standard shaded species are dominants C:/Jobs/Wig/3`d Year Mitigation Report .doc 08/12/10 Chad Armour, LLC 75 FIGURES 76 dVIN AlINIOIA 4 32If10Id 03 Cr) n cD o cu Q ) c " g rn D D2 ccnn O 5'c C CO CD co 0 co 0 0 rn Source: The Thomas Guide, 2002, King/Pierce/Snohomish Counties; Page 655. 31VOS Ol ION Plants Installed on the Tukwila Pond Mtigation site Scientific Name Common Name Erneram) isn.i Fpreatot l Size Trees Alms rubra red alder 47 15' OC 1.5" caliper Fraxinus latifolia Oregon ash 47 15' OC 1.5" caliper Populus balsamifera black cottonwood 31 30' OC 1.5" caliper Salix lasiandra Pacific willow 440 8' OC cuttings Shrubs :Corpus stolonrera red -osier dogwood 338 50 6OC 2-gallon Comas stolonifera red -osier dogwood 338 145 6' OC bare root Lonicera involucrata black twinberry 30 6' OC 2-gallon Physocarpos capdatus Pacific ninebark 30 6' OC 2-gallon Salix piped Piper's willow 124 6' OC cuttings Salix silchensis Sitka willow 123 6' OC cuttings Herbs Beckmannia syzigachne American sloughgrass 2.67Ib 2.671b 2.671b broadcast seed Carex obnupta slough sedge 2253 1336 3,450 24"0C bare root Carex stipata sawbeak sedge 2,380 1,413 3644 24"OC bare root Deschampsia cespitosa tufted hairgrass 3.051b 3.051b 3.051b broadcast seed Eleochds palustris common spike-rush 607 361 930 24"0C bare root Elymus glaucus blue wildrye 2.671b 2.671b 2.671b broadcast seed Seam macrophyllum large -leaved avens 0.51b 0.51b 0.51b broadcast seed Glyseria alata tall mannagrass 0.421b 0.421b 0.421b broadcast seed Glyseria grandis reed mannagrass 0.031b 0.031b 0.031b broadcast seed Glyseria occidentalis western mannagrass 3.58Ib 3.581b 3.581b broadcast seed Hordeum brachvanlherum meadow barley 2.671b 2.671b 2.671b broadcast seed including Existing Degraded Wetland LEGEND Wetland Class Area (SF) Area (Acres) Forested (F0) 58,866 1.35 Scrub -Shrub (SS) 22,868 0.52 Emergent (EM) 37,778 0.87 Open Water (OW) 32,849 0.75 152,361 3.50 Source: Bush. Rood 8 Hitchings, Inc. MITIGATION BOUNDARY LAD NUMBER & LOCATION OF MONITORING WELLS Scrub Shrub EXISTING OW TUKWILA POND MONITOR WELL G-106 �vR �P Existing Forest Emergent MONITOR WELL G-® e/FO a.WEWGEW sue} G-a wWW Forest MONITOR WELL G-115 FO MONITOR WELL G-109 POST -CONSTRUCTION PLAN ao EXISTING FO MONITOR WI, 0--2�1 Assumed Edge of OW .--: MONITOR WELL 5-2 MONITOR WELL 0-101 MONITOR W LL G-I MONITOR WELL 5-I Open GE OF WATER Water / MONITOR WELL G-12 ' 05. _m1 / 001?01, WELL G-10 ' 5 IMO NI TOR WELL 0-11 CGRCREEE SIDEWALK 9e Existing Forest -z- ANDOVER PARKWAY WEST 1 FIGURE 2: POST -CONSTRUCTION PLAN (REVISED) 1 Sig Prapsrtiss LLC-SS Tukwila. Washagten Chad Armour, LLC 1 6500 126111 Alenue SE 1 eflak , WeMhgtw 99006 DWG NAME: G:Vy oj.ot\Clients\armour\69g Praparties\wlg012.deg DATE: 12/23/08 09:34am ATTACHMENT A Representative Photographs 79 Third Annual Wetland Mitigation Monitoring Tukwila, Washington 00,10',N!?kolor Tukwila Pond Mitigation Site Photograph 1. View of the Emergent Wetland from Plot G-101 looking southeast. ��mipmV�Il�lilY� IPIIP,1„„,,, Photograph 2. View of the Emergent Wetland from Plot G-7 looking east. C:/Jobs/Wig/3rd Year Mitigation Report .doc Chad Armour, LLC 08/13/10 80 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site Photograph 3. View of the Scrub -Shrub Wetland from Plot G-109 looking west. dlii1flllY11 h ° I'IIIN „ u Photograph 4. View of the Scrub -Shrub Wetland from Plot G-8 looking east. C:/Jobs/Wig/3rd Year Mitigation Report .doc Chad Armour, LLC 08/13/10 81 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site Photograph 5. View of the Scrub -Shrub Wetland from Plot G-115 looking northeast. IPAV Photograph 6. View of the Forested Wetland from Plot G-105 looking southwest. C:/Jobs/Wig/3rd Year Mitigation Report .doc 08/13/10 Chad Armour, LLC 82 Third Annual Wetland Mitigation Monitoring Tukwila, Washington trl�a�n opl gel 'IIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIlum lilfilmoolovotili MIIYNNG'HMMIIHHNHu ml W��,,,IIIIIIIIII iii luuuuumouuuuuuuu i''1'1'''''11'1'11111'11'1'1'111 I^I lllpll111101,6111111111111111111111111111111111111111111111III III IIIIIIII 11 I� III 111111111111 I1�111111I IINlllllll ul 11 I11 lllluu°uullN'Imulll II rmalwllnmll n'IIIIIII I I uuuiNNNNNNNNNNINN NIIu�N II 1111111111111111111101111111111 Tukwila Pond Mitigation Site III III 111111111111111111111111111 I IIIIIIII 111111111111111II �� Photograph 7. View of the Open Water Wetland from Plot G-10 looking west. „I',�'I1il'd,up1W°wu�l17 SIN I� IbVPVdIIIi'Im I IIII "d � � III I NnI Illiil i IPflI) W III' ull llii 1u uu llll l lill 1, Il YiN lI 11 dwNt"i'IIII' N' lllpltl °IIIIIIIINIf111 ik � i VU,V,Vu ,p'IN'1I ww l I111000I mu pl �fuSI'„i' Ylo m V III kliiVuuuuu liiiiiiiiiiliiiiliiiiiiiliiiiiiiiililiiiiiiiliiliiiiiiiilililiiiiiliiiiiliiliiiilliiiiiiiimuuiilliiiiuiuiiiiuiiiiiiliiliiliiiii„,�„�uulu��l ,„„I�m,IIIIIIN�I�1Vli IIIIiI li�l 1111 Illllllluu � NNVI'^m�l�klm ulll u��m��M el. uu l 1IIIIIIIIIIIIIIIIIyp Photograph 8. View of the Open Water Wetland from Plot G-12 looking southwest. C:/Jobs/Wig/3rd Year Mitigation Report .doc Chad Armour, LLC 08/13/10 83 Third Annual Wetland Mitigation Monitoring Tukwila, Washington Tukwila Pond Mitigation Site Photograph 10. View of the Existing Forested Wetland from Plot G-2 looking southwest. Photograph 10. View of the Existing Forested Wetland from Plot G-4 looking northwest. C:/Jobs/Wig/3rd Year Mitigation Report .doc 08/13/10 Chad Armour, LLC 84 Source: The Thomas Guide, 2002, King/Pierce/Snohomish Counties; Page 655. ukwila Pond Sit NOT TO SCALE FIGURE 1: VICINITY MAP Wig Properties LLC-SS Tukwila, Washington Chad Armour, LLC 6500 126'" Avenue SE Bellevue, Washington 98006 85 Wetland E (179 sf) Wetland A (13,718 sf) •5P-1 P-120 24 .., 23 MINKLER BOULEVARD O P-1 Monitoring Well Designation and Location • SP-1 Plot ID Designation and Approximate Location Photograph Number and Direction Survey Source: Bush, Roed & Hitchings, Inc. 0 80 160 Scale in Feet FIGURE 2: SITE PLAN (REVISED) Wig Properties Tukwila, Washington Chad Armour, LLC 6500 126th Avenue SE Bellevue, Washington 98006 DATE: DWG NAME: 86 07/06/0 rrnour\Wig Properties\wig002.dwg PLANTING DETAIL (6' TO 8' HEIGHT) OTE INTO J t,* WATER ONLY ---"� LANTING DETAIL tc. 441'.'sr COO Aland i52-172 1 7.7`- .0' 40, 6 i0,92 38.4'2• 0,88 17,'�17 7' 22,779 7.7'-182. 22,152 I 0,51 18.2'=1 . ' 28,157 .65 ;A ON_ AREA A 2.2.222 EVSTING EXISTING E GRAO Ep WETLAND' E =._'N - SIGN DETAIL SCALE: NONE LOG LENGTH; 10` — O' LOG 0I:.1#ER.r 6' — LOG DETAIL scALE NONE FENCE DETAIL SCALE:NONE TuK A POND NOTE SNACS TO LE NCILIONG LAE COT MD SNA, IfEMS NON KAM WOO HABITAT SNAG S NONE ISTING F 1111,7 ,vi la lands 1,000 square feet or less 1,001-4,000 square feet 4,000 square feet or larger TITLE 18 — ZONING Sections: 18.70.010 18.70.020 18.70.030 18.70.040 18.70.050 18.70.060 18.70.070 18.70.080 18.70.090 18.70.100 18.70.110 18.70.120 18.70.130 CHAP f�� 00000IOR 1 870 NO ,C 14IIII OIIklVlIIIIit G ILOTS, sT'f"RUC°T"UURES A i`IIII) usIllr''`;$ Purpose Construction Approved Prior to Adoption of Title Substandard Lots Nonconforming Uses Nonconforming Structures Repairs and Maintenance Building Safety Nonconforming Parking Lots Nonconforming Landscape Areas Conditional and Unclassified Uses Nonconforming Adult Entertainment Establishment Sidewalk Dedication Cargo Containers 18.70.010 Purpose It is the purpose of this chapter to establish limitations on the expansion and extension of nonconforming uses and structures which adversely affect the development and perpetuation of desirable residential, commercial, and industrial areas with appropriate groupings of compatible and related uses. (Or 1819 §1 (tram), 1997) 18.70.020 Construction Approved Prior to Adoption of Title To avoid undue hardship, nothing in this title shall be deemed to require a change in plans, construction or designated use of any building on which actual construction was lawfully begun prior to adoption of this title and upon which actual building construction has been carried on in a diligent manner. Actual construction shall consist of materials in permanent positions and fastened in a permanent manner, and demolition, elimination and removal of one or more existing structures in connection with such construction; providing, that actual construction work shall be diligently carried on until the completion of the structure involved. (Ord 1819 §1 (a 1, 1 1( 18.70.030 Sustandard Lots A. A lot, as defined in TMC 18.06.500, which does not meet the minimum standard for average lot width for the zone in which it is located, may still be developed as a separate lot if the proposed use is one which is permitted in the zone, and the proposed development can comply with the remaining requirements of this title regarding basic development standards for the applicable zone and other applicable land use and environmental requirements. B. A lot, as defined in TMC 18.06.500, which cannot meet the basic development standards (other than lot width) for the applicable zone and other applicable land use and environmental requirements, may be developed only if it is combined with adjacent lot(s) in a manner which allows the combined lots to be developed in a manner which does comply with the basic development standards for the applicable zone and other applicable land use and environmental requirements. In the event lots are combined in order to comply with the requirements of this subsection, a boundary line adjustment shall occur so that the combined lots are henceforth considered a single lot. C. Nothing in this subsection shall be deemed to prevent the owner of a sub -standard lot from applying for or receiving approval of variances pursuant to TMC Chapter 18.72. 18.'70.040 NonconformingUses Any preexisting lawful use of land made nonconforming under the terms of this title may be continued as a nonconforming use, defined in TMC Chapter 18.06, so long as that use remains lawful, subject to the following: 1. No such nonconforming use shall be enlarged, intensified, increased or extended to occupy a greater use of the land, structure or combination of the two, than was occupied at the effective date of adoption of this title. 2. No nonconforming use shall be moved or extended in whole or in part to any other portion of the lot or parcel occupied by such use at the effective date of adoption or amendment of this title. 3. If any such nonconforming use ceases for any reason for a period of more than six consecutive months, or a total of 365 days in a three-year time period, whichever occurs first, any subsequent use shall conform to the regulations specified by this title for the district in which such use is located. 4. No existing structure devoted to a use not permitted by this title in the zone in which it is located shall be structurally altered, except in changing the use of the structure to a use permitted in the zone in which it is located; except where minor alterations are made, pursuant to TMC Section 18.70.050(1), TMC Section 18.70.060, or any other pertinent section, herein. 5. If a change of use is proposed to a use determined to be nonconforming by application of provisions in this title, the proposed new use must be a permitted use in its zone or a use approved under a Conditional Use or Unclassified Use Permit process, subject to review and approval by the Hearing Examiner and/or the City Council. For purposes of implementing this section, a change of use constitutes a change from one Permitted, Conditional or Unclassified Use category to another such use category as listed within the Zoning Code. 6. Any structure, or structure and land in combination, in or on which a nonconforming use is superseded by a permitted use, shall thereafter conform to the regulations for the zone in which such structure is located, and the nonconforming use may not thereafter be resumed. (Ord 111100 § 1,2016; Ord 1819 §1(1(, 111111( Produced by the City of Tukwila, City Clerk's Office Page 18-209 91 TUKWILA MUNICIPAL CODE 18.70.050 Nonconforming Structures Where a lawful structure exists at the effective date of adoption of this title that could not be built under the terms of this title by reason of restrictions on area, development area, height, yards or other characteristics of the structure, it may be continued so long as the structure remains otherwise lawful subject to the following provisions: 1. No such structure may be enlarged or altered in such a way that increases its degree of nonconformity. Ordinary maintenance of a nonconforming structure is permitted, pursuant to TMC Section 18.70.060, including but not limited to painting, roof repair and replacement, plumbing, wiring, mechanical equipment repair/replacement and weatherization. These and other alterations, additions or enlargements may be allowed as long as the work done does not extend further into any required yard or violate any other portion of this title. Complete plans shall be required of all work contemplated under this section. 2. Should such structure be destroyed by any means to an extent of more than 50% of its replacement cost at time of destruction, in the judgment of the City's Building Official, it shall not be reconstructed except in conformity with provisions of this title, except that in the LDR zone, structures that are nonconforming in regard to yard setbacks or sensitive area buffers, but were in conformance at the time of construction may be reconstructed to their original dimensions and location on the lot. 3. Should such structure be moved for any reason or any distance whatsoever, it shall thereafter conform to the regulations for the zone in which it is located after it is moved. 4. When a nonconforming structure, or structure and premises in combination, is vacated or abandoned for 24 consecutive months, the structure, or structure and premises in combination, shall thereafter be required to be in conformance with the regulations of the zone in which it is located. Upon request of the owner, the City Council may grant an extension of time beyond the 24 consecutive months. 5. Residential structures and uses located in any single-family or multiple -family residential zoning district and in existence at the time of adoption of this title shall not be deemed nonconforming in terms of bulk, use, or density provisions of this title. Such buildings may be rebuilt after a fire or other natural disaster to their original dimensions and bulk, but may not be changed except as provided in the non -conforming uses section of this chapter. 6. Single-family structures in single- or multiple -family residential zone districts that have legally nonconforming building setbacks, shall be allowed to expand the ground floor only along the existing building line(s), so long as the existing distance from the nearest point of the structure to the property line is not reduced, and the square footage of new intrusion into the setback does not exceed 50% of the square footage of the current intrusion. 7. In wetlands, watercourses and their buffers, existing structures that do not meet the requirements of the Sensitive Areas Overlay District chapter of this title may be remodeled, reconstructed or replaced, provided that: a. The new construction does not further intrude into or adversely impact an undeveloped sensitive area or the required buffer; b. The new construction does not threaten the public health, safety or welfare; and c. The structure otherwise meets the requirements of this chapter. 8. In areas of potential geologic instability, coal mine hazard areas, and buffers, as defined in the Sensitive Areas Overlay District chapter of this title, existing structures may be remodeled, reconstructed or replaced, provided that: a. The new construction is subject to the geotechnical report requirements and standards of TMC Sections 18.45.120B and 18.45.120C; b. The new construction does not threaten the public health, safety or welfare; c. The new construction does not increase the potential for soil erosion or result in unacceptable risk or damage to existing or potential development or to neighboring properties; and d. The structure otherwise meets the requirements of this chapter. 9. A nonconforming use, within a nonconforming structure, shall not be allowed to expand into any other portion of the nonconforming structure. (Ord, 2518 §15, 2016; Ord, 2175 1, 2007; Ord, 2077 §1, 2004; Ord, 1819 "t (part), 1997) 18.70.060 Repairs and Maintenance If any building is devoted in whole or in part to any nonconforming use, work may be done in any period of twelve consecutive months on ordinary repairs, or on repair or replacement of nonbearing walls, fixtures, wiring or plumbing to an extent not exceeding 25% of the current replacement value of the building. (Ord. 1819 §1 (part), 1997) 18.70.070 Building Safety A. Nothing in this title shall be deemed to prevent the strengthening or restoring to a safe condition of any nonconforming building or part thereof declared to be unsafe by order of any City official charged with protecting the public safety. B. Alterations or expansion of a nonconforming use which are required by law or a public agency in order to comply with public health or safety regulations are the only alterations or expansions allowed. (rd. 1819 §1(mart), 1997) 18.70.080 Nonconforming Parking Lots A. Nothing contained in the Off-street Parking and Loading Regulations chapter of this title shall be construed to require a change in any aspect of a structure or facility covered thereunder including, without limitation, parking lot layout, loading space Page 18-210 92 Produced by the City of Tukwila, City Clerk's Office evue quah TAC t Moines wila to the critical area isn't increased. Prohibited if it further encroaches on the critical area Building expansion over existing impervious surface area within the buffer is allowed provided the building expansion does not encroach closer toward a wetland or stream. Nothing mentioned Existing buildings may expand vertically to add upper stories. Nothing mentioned Nothing mentioned Minor, nonstructural, and repairs of mechanical systems within or supporting the accessory structure allowed Nothing mentioned Repair and maintenance of non- conforming uses or structures is permitted provided they do not increase the degree of nonconformity harm critical area further. If destroyed by an unforseen circumstance, the structure can be rebuilt in the same footprint, if commenced within one year of destruction. Temporary distrubance of surrounding areas from this construction will be restored afterwards. If destroyed by an unforseen circumstance, the structure can be rebuilt in the same footprint. Nothing mentioned Reconstruction or additions to existing structures that intrude into critical areas or their buffers shall not increase the amount of such intrusion potential stormwater impacts to groundwater. Nothing mentioned Nothing mentioned Nothing mentioned Where a legally established, nonconforming use of the buffer exists (e.g., a road or structure that lies within the width of buffer recommended for that wetland), proposed actions in the buffer may be permitted as long as they do not increase the degree of nonconformity, or if no reasonable alternative exists. This means no increase in the impacts to the wetland from activities in the buffer. Nothing mentioned Allowed if the Allowed if it doesn't reconstruction doesn't Nothing mentioned Nothing mentioned affect the critical area intrude further into or or buffer impact the sensitive area or buffer Only permitted if it doesn't infringe further into Eton the critical area or increases the level of Nothing mentioned nonconformity If it doesn't increase the level of nonconformity, Upper floor additions are allowed above the ground floor of an existing Can only be reconstructed if the new structure or use is in conformity with the code, except for ongoing argricultural use. Can be reconstructed if Nothing mentioned nvn, ncinn is , IInsA,nrl if if nn nrn nfn rminrr A lInsA,nrl rirnniirinrl +k,+ tk0 nasA, rnnctrtirt inn 94 ATTAC ENT 1' Kirkland Zoning Code: 90.185 Nonconformances in Critical Areas 6. Expansion of Nonconforming Building that Increases the Nonconformance — An existing, legally established nonconforming building may be expanded into a critical area buffer or the building setback under the following standards and limitations: a. General Standards for Any Expansion 1) Expansion is only permitted for those buildings that have not received City approval for a critical area or buffer modification allowed under this or a previous code or not received approval for a reasonable use exception pursuant to KZC 90.180; 2) A one (1) time expansion of each option found in subsections (6)(b) through (e) of this section is permitted on a subject property. No more than one expansion is permitted for each option. See vegetative buffer standards in KZC 90.130; 3) No expansion is permitted in a critical area buffer that is a fish and wildlife conservation area without an approved management plan pursuant to KZC 90.95; 4) The following nonconforming improvements are allowed without going through review under subsections (6)(b) through (e) of this section if a new or replacement foundation is not required: a) Upper floor additions are allowed above the ground floor of an existing nonconforming building if they do not encroach closer to the critical area buffer or structure setback from the buffer beyond the existing exterior walls; b) Existing carports and decks with roofs may be enclosed if the new exterior walls do not extend beyond the existing foundation or corner supports of the structure; and c) An interior open courtyard of an existing building may be enclosed if the courtyard is covered entirely with impervious material. See subsection (6)(d) of this section if the material is not entirely impervious; 5) Covering an existing deck with a roof or an existing pathway with a breezeway or similar improvements may be proposed using subsections (6)(b) through (e) of this section; 6) Any commercial parking required for additions shall not be located in the critical area buffer; 7) A critical area determination, report and a survey pursuant to KZC 90.105 and 90.110 are required if the wetland has not been rated and delineated pursuant to KZC 90.55 within the past five (5) years or the stream has not been classified or delineated pursuant to KZC 90.65; 8) Compensatory mitigation through buffer restoration shall be provided as follows: 95 a) A native vegetative buffer at a minimum ratio of 1:1 (new footprint area is equal to or less than vegetative buffer area) shall be provided; b) If the new or expanded building footprint results in removal of a significant tree in a buffer, the tree shall be replaced with two (2) native trees in the buffer. The replacement tree shall be six (6) feet tall for a conifer and 2-inch caliper for deciduous or broadleaf. For a removed significant tree in a buffer that is 24 inches in diameter, the tree shall be replaced with three (3) native trees; c) The vegetative buffer shall be located along the edge of the critical area or as close to the critical area as possible if the critical area is located off -site; d) The vegetative buffer shall be 10 feet in depth and located across from the building expansion area; e) The buffer vegetative standards pursuant to KZC 90.130 shall be used as a guideline for the mitigation area; and f) The mitigation is in addition to revegetation of any disturbed area; 9) A mitigation planting plan, prepared by a qualified critical area professional approved by the City, shall be submitted for approval as part of the building permit. Prior to final inspection, replanting of any disturbed area and the mitigation planting shall be installed by the applicant and inspected by the City; 10) A performance and three-year maintenance and monitoring security shall be submitted with the building permit pursuant to KZC 90.165 for the mitigation plan; 11) Permanent critical area fencing and signage is required. Prior to issuance of a building permit, the Planning Official shall determine the location of the required critical area fencing and signage to be installed pursuant to KZC 90.190. a) The fencing shall be located at the edge of the buffer. However, if all or portions of the buffer is covered by legally established lawn, nonnative vegetation and/or improvements, then the fencing shall be located at the boundary of that maintained area; b) If the critical area is off site and that maintained area extends to the property line, then the fencing shall be located at the property line; and c) Existing buffer fencing may need to be relocated to meet this provision; 12) A critical area covenant on a form approved by the City shall be recorded along with an as -built site plan showing the location of the approved expansion and mitigation vegetation in the buffer to protect the vegetated portion of the buffer in perpetuity. A critical area dedication pursuant to KZC 90.210 is not required for the vegetated portion of the buffer. 96 b. Expansion into Critical Area Buffer on Side of the Building Opposite of Critical Area 1) The footprint of an existing building may be expanded into the critical area buffer on the side of the building opposite of the critical area buffer up to a maximum of 1,000 square feet. The existing building must be between the addition and the critical area (see Chapter 180 KZC, Plate 26); 2) Only a one (1) time expansion of this option is permitted for the subject property. See subsection (6)(a)(2) of this section; and 3) See general standards in subsection (6)(a) of this section for an expansion. c. Expansion into Structure Setback from the Buffer 1) The footprint of an existing building may be expanded into the structure setback up to a maximum of 500 square feet; 2) If an addition is located at the edge of the buffer, the portion of the buffer next to the side of the addition abutting the buffer is considered a structure setback from the buffer. Only necessary maintenance and repair of the addition are permitted in this portion of the structure setback. No improvements pursuant to KZC 90.140 are permitted in this portion of the structure setback; 3) Only a one (1) time expansion of this option is permitted for the subject property. See subsections (6)(a)(2) of this section; and 4) See general standards in subsection (6)(a) of this section for a building expansion. d. Expansion into Critical Area Buffer but No Closer than the Existing Building 1) The footprint of an existing building may be expanded into the critical area buffer, but no closer than the edge of the existing building nearest to the critical area, up to a maximum of 500 square feet (see Chapter 180 KZC, Plate 26); 2) An interior open courtyard of an existing building may be enclosed up to 500 square feet if the courtyard is covered partially or entirely with pervious material. This improvement can be done in conjunction with subsection (6)(d)(1) of this section if the total new impervious area of the expanded building does not exceed 500 square feet; 3) The minimum buffer width for the addition shall be 60 percent of the required buffer width standard pursuant to KZC 90.55 for wetlands and KZC 90.65 for streams; 4) Only a one (1) time expansion of this option is permitted for the subject property. See subsections (6)(a)(2) of this section; and 5) See general standards in subsection (6)(a) of this section for a building expansion. 97 e. Expansion into Critical Area Buffer between the Building and the Critical Area 1) The footprint of a building may be expanded into the critical area buffer between the building and the critical area up to a maximum of 250 square feet (see Chapter 180 KZC, Plate 26); 2) The new footprint must be attached to the original building and not to any subsequent footprint addition under subsection (6) of this section; 3) The minimum buffer width for the addition shall be 60 percent of the required buffer width standard pursuant to KZC 90.55 for wetlands and KZC 90.65 for streams; 4) Only a one (1) time expansion of this option is permitted for the subject property. See subsection (6)(a)(2) of this section; and 5) See general standards in subsection (6)(a) of this section for a building expansion. 98