Memorandum
City of Lawrence
Utilities Department
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TO: |
David L. Corliss – City Manager Cynthia Wagner - Assistant City Manager Diane Stoddard - Assistant City Manager |
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FROM: |
Philip Ciesielski – Assistant Utilities Director |
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CC: |
Dave Wagner – Director of Utilities Mike Lawless – Assistant Utilities Director Beth Krishtalka – Assistant to Director Mark Hegeman – Utilities Operations Superintendent Dave King – Utilities Maintenance Superintendent |
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Date: |
March 4, 2013 |
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RE: |
Agenda Item – Authorize Staff to Negotiate with Black & Veatch for Engineering Services for Project UT1102KA Kaw WTP Raw Water Intake Replacement |
Please include the following item on the City Commission Agenda for consideration at the March 12, 2013 meeting:
Authorize Staff to Negotiate a Supplemental Agreement to the existing Engineering Services Contract with Black & Veatch for Engineering Services for Project UT1102KA Kaw WTP Raw Water Intake Replacement
Project Description
The recommended project provides for the design of a redundant surface water intake and raw water pipeline to the Kaw Water Treatment Plant (WTP) as recommended in the November 2012 Kaw Water Treatment Plant Raw Water Intake Evaluation by Black & Veatch. The construction of the intake and raw water pipeline will provide a redundant point of intake from the Kansas River for the Kaw WTP. These facilities will also serve as the first phase of Kansas River raw water supply required for the potential expansion of the Kaw WTP to a treatment capacity of 25 MGD. See the attached map indicating the location of the existing intake structures.
Project History
January 24, 2012 - City Commission authorized execution of the Engineering Services Agreement for the work.
September 5, 2012 - Received draft report.
September 20, 2012 - Provided Staff review comments to Black & Veatch.
November 20, 2012 - Received updated report.
December 18, 2012 – City Commission authorized execution of Supplemental Agreement for the design of immediate modifications to the existing intake structure and dredging of accumulated river bed material in the vicinity of the intake. These improvements are currently being designed and permitted with dredging expected to take place this summer and construction of the modifications during fall and winter.
Project Status
Staff have reviewed the November 2012 report and its proposed raw water intake options ranging from a new surface water intake to horizontal collector wells. The river analysis and potential surface water and collector well projects are summarized below. Based on an evaluation of the capital, and operations and maintenance costs of the proposed options outlined below, Staff recommend proceeding with the new Kansas River surface water intake project.
River Analysis
50% exceedance flow rate* velocities in the area of the intakes are in the range of incipient bed movement. 90% exceedance flow rate* and above the majority of the river reach is in the significant movement velocity range, meaning the majority of the river bed is mobile under these flow conditions. River bed dunes up to 3 ft tall are mobile under these conditions. Given the current river bed elevation in the vicinity of intakes recent sand inundation issues are most likely due to river bed material flowing into the intake, not as much as suspended material in the water column settling out.
xx% exceedance event is the discharge that is greater than xx% of the discharges for the period of record.
Suspended sand load in the river; 100 tons/day @ 4,000 cfs; 100,000 tons/day @ 40,000 cfs (2 yr event)
The current operational intake (Intake 1) is in an area of low water velocity with very little potential for scour velocities to provide removal of accumulated material from around the structure.
There is a hole with channel depths up to 20 ft upstream of out of service Intake 3 (eastern most).
Intake 3 is in the area of highest flow velocities with potential velocities sufficient to provide scouring around the structure.
River bed elevations downstream of the existing intakes are consistent with the area around the intakes and this area is not recommended for locating a new structure.
Construction of dikes to influence flow and velocity patterns in the river around the intakes are problematic due to the locations of adjacent intakes and restrictions to river passage.
Bowersock’s new operations with the deeper mill pond will extend the duration of upstream pooling increasing sedimentation. However, they will not reduce flow velocities to the point that the river bed is not mobile.
Surface Water Options
Modify the interior of Intake 1, construct a new 25 mgd intake and pipe at location of Intake 3 (eastern most). Intake 1 would continue to need to be monitored and cleaned out.
Construct a second low service pump facility to provide 25 mgd firm pumping capacity of raw water.
Modify Intake 1 - $225,000.00
Construct New Intake Crib and Piping - $4,587,000.00
Construct New Raw Water Pump Station – $7,919,000.00
Total Construction - $12,646,000.00
20 yr Present Worth w/ Energy and Treatment Impacts - $14,006,000.00
Continued use of surface water does not address issues with taste and odor compounds, algal toxins, zebra mussels nor O&M related to ongoing sand issues.
Horizontal Collector Well (HCW) Field Options
Burcham Park area is not viable aquifer at the required capacities.
Airport area is viable in terms of quantity but resulting aquifer drawdown would be detrimental to surrounding wells and would not be permitted by State.
There is a viable aquifer area adjacent to the river upstream of the Westar facility.
Modify Intake 1 - $225,000.00 (keep in service as HCW’s phased in)
25 mgd well field, 3 wells w/ backup generators - $21,612,000.00
(single well $7,204,000.00)
36” Raw water transmission main - $8,818,000.00
Total Construction 25 MGD HCW and transmission main - $30,570,000.00
20 yr Present Worth w/ Energy and Treatment Impacts - $33,586,000.00
Use of ground water is anticipated to result in reduced taste and odor and algal toxin compounds, eliminate issues of zebra mussels, eliminate intake icing issues, provide raw water with lower total organic carbon resulting in less disinfection byproduct formation potential, eliminates river sedimentation and Bowersock operational factors, and provides consistent water quality resulting more stable treatment processes. The quantity of water anticipated to be available at the proposed location upstream of Westar could also provide additional raw water for the Clinton Water Treatment Plant.
Project Funding: The project is funded from the Department of Utilities 2013 Capital Improvements and Rate Plan.
Action Request: Authorize Staff to Negotiate a Supplemental Agreement to the existing Engineering Services Contract with Black & Veatch for Engineering Services for Project UT1102KA Kaw WTP Raw Water Intake Replacement
Thank you for your assistance. Please advise if you have any questions.