Memorandum

City of Lawrence

Utilities Department

TO:	City Commission
FROM:	Philip Ciesielski Utilities Engineer
CC:	Mike Wildgen, City Manager Debbie Van Saun, Asst. City Manager Dave Corliss, Asst. City Manager Dave Wagner, Asst. Utilities Director Linda Finger, Planning Director Lisa Pool, Planner
Date:	October 26, 2005
RE:	Doolittle Subdivision – Sanitary Sewer Connection

The following information is to address concerns regarding the subdivision’s sanitary sewer connection which were raised by Commissioner Schauner during the rezoning request for the Doolittle Subdivision.  The rezoning request was an item on the Tuesday October 18, 2005 City Commission Consent Agenda.

The Doolittle Subdivision is situated north of Overland Drive and west of Monterey Way.  The area to be developed straddles the ridge which divides the Kansas River-2 (KR2) and Wakarusa River-3 (WR3) sanitary sewer subbasins. 

The original plan, submitted by the developer and BG Consultants, to connect the subdivision to the City’s sanitary sewer collection system was based on flow being directed to existing gravity sewer lines in the KR2 basin.  The proposed points of connection represented the existing sanitary sewer lines most adjacent to the proposed subdivision.

During the evaluation of the development’s Downstream Sanitary Sewer Analysis, staff determined that there may be limited capacity in the downstream receiving interceptor lines along Peterson Road.  As a result, connection into the KR2 system was going to be denied.

During this same time period, Wade & Associates completed the flow monitoring and modeling study for the Alvamar Area Sanitary Sewer Improvements in the WR3 basin.  At the request of staff, Wade & Assoc., using their hydraulic model for the WR3 basin, confirmed that the addition of the Doolittle Subdivision flows would not expand the timing, size or scope of the recommended improvements in the WR3 basin.

It is appropriate to note that the 2003 Wastewater Master Plan recommendations generally discourage flows from being transported across basins, especially with the use of pump stations.  The above information regarding available capacity in WR3, in conjunction with the fact that the proposed development sits in both the KR2 and WR3 basins, resulted in the currently recommended proposal to accommodate the subdivision’s sanitary sewer flows via gravity in the WR3 basin.