HomeMy WebLinkAboutUtilities 2012-10-23 Item 2C - Contract Supplement #3 - Water and Sewer Comprehensive Plan with Carollo EngineersCit of Tukwila
Jim Haggerton, Mayor
INFORMATIONAL MEMORANDUM
TO:
Mayor Haggerton
Utilities Committee
FROM:
Bob Giberson Public Works Director
BY:
Mike Cusick, PE, Senior Engineer
DATE:
October 19, 2012
SUBJECT:
Water and Sewer Comprehensive Plans
Project No. 91040101, Contract No. 10 -055
Supplemental Agreement No. 3
ISSUE
Approve Supplemental Agreement No. 3 with Carollo Engineers to revise the Comprehensive
Water Plan.
BACKGROUND
In 2010 the City contracted with Carollo Engineers to update the Water Comprehensive Plan.
DISCUSSION
For the 2005 Comprehensive Water Plan, the Washington State Department of Health (DOH)
required no additional storage of water in lieu of the existing 2 million gallon reservoir and
multiple taps off Seattle pipelines. In 2009, DOH guidelines were revised to require standby
storage of water at 200 gallons per equivalent residential unit (ERU). With the 2009 DOH
storage guidelines, the existing Tukwila 2 million gallon reservoir is now undersized for the
current population of the city. With the projected 2030 population growth model provided by
the Tukwila Department of Community Development (DCD), the condition worsens.
Initially, Carollo Engineers used the 2010 -2030 population data study from Puget Sound
Regional Council (PSRC), as provided by DCD, to determine the required reservoir size to
meet the revised requirements from DOH. Using the PSRC 2030 population model, the City
of Tukwila would be required to construct a new reservoir to bring the City's total water
storage to 7.1 million gallons with a design and construction cost for the proposed reservoir at
over $5.5 million dollars. This cost estimate does not include the cost of land acquisition for
the reservoir and a necessary pump station. The total cost of the project could be over $10
million dollars for the reservoir, pump station, and land.
With the high cost of the required water reservoir and other water CIP improvements, Public
Works questioned DCD on the projected 2030 population growth model for the City. It was
agreed that the 2030 PSRC model used for population forecasting overstates projected
growth within the City. For the Comprehensive Water Plan, DCD agreed to cut the projected
growth in half by changing the time period from 2010 -2030 to 2010 -2040. With a reduced
population growth, the total reservoir requirement of 7.1 million gallons can be reduced to 4 to
5 million gallons of total storage. The reduction in reservoir size results in savings to the City
of several million dollars in costs to the Water Fund.
Carollo Engineers additional work will modify the Water Comprehensive Plan. The
supplement will focus on updating the revised growth projections with the new 2012 data
39
Info Memo Page 2
Carollo Engineers Supplement No. 3
developed by DCD. The reduced growth projections will be used to calculate new average
and maximum day water demand for future planning scenarios. The new demand will be
updated in the supply analysis, hydraulic modeling analysis, and storage analysis. The
system will be evaluated to determine the deficiencies and proposed improvements needed
with the new demand in each service area. It is anticipated that this will also modify the
proposed improvements in the CIP and this new data will modify most sections of the Water
Comp Plan.
FINANCIAL IMPACT
Supplemental Agreement No. 3 will increase the consultant's scope of work for Task 300
Planning Considerations for $16,250.00. Funding for the additional work will come from the
Interurban Water Reuse Project, page 86 of the 2012 CIP at $25,000.00 and Andover Park
West Water Line Project for $16,000.00, which will now be constructed in 2013.
EXPENDITURES
Original contract
Supplement No. 1
Supplement No. 2
Supplement No. 3
Total
$291,000.00
12, 662.00
21,721.50
16.250.00
$341,633.50
Fundina Budaet
Water Comp Plan
$160,000.00
Sewer Comp Plan
143,000.00
Interurban Water Reuse
25,000.00
APE Water Line
16.000.00
E, M
RECOMMENDATION
Approve Supplemental Agreement No. 3 to Contract No. 10 -055 with Carollo Engineers for
$16,250.00 to update population growth projects for the Comprehensive Water Plan and
consider this item at the November 13, 2012 Committee of the Whole and subsequent
November 19, 2012 Regular Meeting.
Attachment: Supplemental Agreement No. 3
WAPW EngTROJECT9k WT Pm*tslWater Comprehensive Plan -Water (91040101)ilnio Memo Carrollo Sup 10-16-12.dm
40
SUPPLEMENTAL AGREEMENT NUMBER 3
to
C
THIS SUPPLEMENTAL AGREEMENT is entered into between the City of Tukwila, Washington,
herein -after referred to as "the City," and Carollo Engineers hereinafter referred to as "the Consultant in
consideration of the mutual benefits, terms, and conditions hereinafter specified.
The City desires to supplement the agreement entered into with the Consultant and executed on, May 19,
2010, and identified as Agreement No. 10 -055. All provisions in the basic agreement remain in effect
except as expressly modified by this supplement.
The changes to the agreement are described as follows:
1. Scope of Services, for Supplemental Agreement #3 to the Comprehensive Sewer and Water Plans
(Plans) for the City of Tukwila. The purpose of this supplement is to add:
The following work effort is a modification to the Comprehensive Plan (Plan) for the City of
Tukwila. The update will be focused on updating the revised growth projections with the new
2012 data developed by the Planning Department. The growth projections will be used to
calculate new average and maximum day water demand for the future planning scenarios. Tile
new demand will be updated in the supply analysis, hydraulic modeling analysis and the storage
analysis. The system will be evaluated to determine the deficiencies and proposed improvements
needed with the new demand in each service area. It is anticipated that this will also modify the
proposed improvements in the CIP. This new data will modify most sections of the Plan.
2. Deliverables, Carollo will prepare a revised Executive Summary and Chapters 2, 3, 5, 6, 7 that
summarizes the new future demand, analysis and recommended improvements.
3. Time for Performance, is amended to change the number of calendar days for completion of the
work to read an additional 90 days for a total of 1,070 days.
4. Payment, shall be amended as follows:
Payment for the work provided by the Consultant as part of this supplement shall be made for an
additional $16,250.00. The total amount for the Consultant for this contact shall not exceed
$341,633.50 without express written modification of the Agreement signed by the City.
DATED this day of 2012.
CITY OF TUKWILA
Jim Haggerton, Mayor
CONSULTANT
By:
Lara Kammereck, Associate Vice President
41