Memorandum

City of Lawrence

Utilities Department

 

TO:

David Corliss – City Manager

Debbie Van Saun – Assistant City Manager

FROM:

Philip Ciesielski – Utilities Engineer

CC:

Dave Wagner – Director of Utilities

Date:

April 11, 2007

RE:

April 17, 2007 City Commission Agenda - Baldwin Creek No.1 Sanitary Sewer Benefit District – Additional Sanitary Sewer Flow Capacity; West Baldwin Creek Sanitary Sewer Interceptor RFP

 

Please include the following item on the City Commission Agenda for consideration at the April 17, 2007 meeting:

Authorize advertisement of a Request for Proposals (RFP) for engineering and construction services for the design and construction of the West Baldwin Creek Sanitary Sewer Interceptor identified in the 2003 Wastewater Master Plan generally as E-BC-1-02, E-BC-2-01 and E-BC-2-02.

Background Information:  The following outlines the recommended plan to provide sanitary sewer service to the developing area in Northwest Lawrence that extends approximately 1 mile north of 6th Street, and is bounded on the east by Queens Road, and the west by the South Lawrence Trafficway.  The recommendations are based on the 2003 Wastewater Master Plan, the May 2006 Draft Northwest Area Master Plan Update by Black & Veatch and recent implementation of the Pump Station PS48 project.  The attached map illustrates the location and components of this Interceptor Project.

 

Initial efforts to provide sanitary sewer capacity to this area included the creation of the Baldwin Creek No.1 Sanitary Sewer Benefit District (BC1 Benefit District) and the construction of Pump Station PS45 with a capacity of 1.1 MGD (million gallons per day).  The total project cost for the BC1 Benefit District was $354,417.37.  PS45 was accepted and put into service in August of 2002.  To date there has been no development related construction within this benefit district and PS45 has yet to have sanitary sewer services connected to it.  Pending development requests in the BC1 Benefit District will exceed the existing pumping capacity of PS45 by approximately 0.7 MGD.  The table below indicates the pending development, its capacity participation in the BC1 Benefit District, the development’s required capacity, per the current proposed land use.

         

Development            PS45 Flow Participation (gpm)                   Developed Flow (gpm)

Mercato                            400                                                     575             

Oregon Trail                      191                                                     332             

Root LLC/Graham               23                                                        53             

Turner                              46                                                      102             

Loges Addition                    155                                                     236             

 

Utilizing current proposed land use and population information, the Northwest Area Master Plan Update evaluated options for the extension of sanitary sewer service to the Northwest area of Lawrence, including the ability to accommodate flows in excess of PS45’s current capacity.  The recommended option continues to utilize PS45 in its current configuration (1.1 MGD capacity).  Flows in excess of PS45’s capacity will be accommodated through the extension of gravity sanitary sewer interceptor lines from PS48 (currently under construction) to the BC1 Benefit District area.  PS48 would convey these flows to the existing PS16, located at 6th & Kentucky, and from there the flows would be pumped to the Wastewater Treatment Plant on E. 8th Street.  PS16 is currently under going a planned expansion from a capacity of 8 MGD to 18 MGD.  Part of the driver for this expansion, which was recommended in the 2003 Wastewater Master Plan, was the pumping of additional Northwest area flows from what is the PS48 facility.

 

Project Cost Estimates:  Efforts to estimate the project cost based on updated alignment information, pipe size, and aerial photography has resulted in a $3.4 million dollar project estimate. The proposed interceptor project and cost is based on pipe size that would provide service to an area in excess of the BC1 Benefit District.  The cost of these improvements to the BC1 Benefit District for flows in excess of PS45’s capacity is the area’s percentage contribution based on its flow relative to the total capacity of the pipe segments.  These costs are outlined in the table below.  It is estimated the BC1 Benefit District’s share of the gravity interceptor line would be approximately $321,350.00. Similar to the PS48 project, the full cost of the proposed gravity interceptor project will be recovered over time as new developments in the drainage area make connections to the line and PS48.

                            

                             Cost for Additional Capacity via

Development            West Baldwin Creek Interceptor                                            

Mercato                            $116,431                         

Oregon Trail                          93,810                         

Root LLC/Graham                   19,960

Turner                                 37,258

Loges Addition                       53,891

 

The costs represented in this document do not include the public improvements required within the BC1 Benefit District to collect the sanitary sewer flows and convey them to PS45 and the proposed gravity interceptors.

                            

Project Status:  PS48 and its force main are being constructed with an initial firm capacity of approximately 6.2 MGD.  The pump station is being constructed to accommodate expanded pumping capabilities and the site is situated to allow for the construction of future wet weather flow storage basins.  The initial gravity service area to PS48, which includes the areas contributing to the Free State Interceptor and the undeveloped areas to the south and east of PS48, have the potential to contribute a peak wastewater flow of approximately 3.0 MGD. Addition of the 0.7 MGD flow from the BC1 Benefit District to PS48 would leave 2.5 MGD of the pump station’s initial capacity for future growth.    

 

The recommended improvements are in accordance with the recommendations in the 2003 Wastewater Master Plan and the May 2006 Draft Northwest Area Master Plan Update by Black & Veatch.  The construction of the proposed gravity interceptor to PS48 also positions the Northwest Area of Lawrence for additional development in the Baldwin Creek Benefit Drainage Basins.

 

The downstream improvements necessary to support the construction of the proposed interceptor sewer, PS48 and its associated force main, are underway and scheduled to be operational by the end of this summer. Staff has evaluated the potential flows to the West Baldwin Creek Interceptor Sewer and preliminary pipe sizes and costs have been determined. The land owners and developers in the area north of 6th Street and west of the South Lawrence Trafficway will be first to be served by this line.  They have been briefed on the project, its potential timeline and cost participation. The Request for Proposal document has been prepared and is ready to advertise.

 

Project Funding:  Funding for the project will ultimately be shared by development benefiting from this infrastructure improvement through the payment of special connection charges.

 

Action Request:  Staff is requesting City Commission authorization to advertise a Request for Proposals for Design-Build teams for the Preliminary Design and submission of a Guaranteed Maximum Price for construction of the West Baldwin Creek Interceptor Sewer project.