Title
Personal Services Agreement Amendment No. 1 for Services During Construction with Wallis Engineering for the 2020 Inflow Reduction Project
Body
RECOMMENDED ACTION (Motion):
Authorize the City Manager to execute Amendment No. 1 with Wallis Engineering to provide services during construction for the 2020 Inflow Reduction Project (CI 19-017) in the amount of $68,025.34.
EXECUTIVE SUMMARY:
Amendment 1 of Personal Services Agreement for Services During Construction with Wallis Engineering for the 2020 Inflow Reduction Project.
BACKGROUND:
The City of Oregon City's Sanitary Sewer Master Plan (SSMP) became effective November 1, 2014. During the update of the master plan, the City's consultant, Brown and Caldwell (B&C), evaluated the City’s sanitary sewer system. The City conducted smoke testing in the sanitary sewer system throughout three basins in 2016. Smoke testing is a necessary course of action to improve the sewer collection system by reducing unwanted stormwater inflow and infiltration.
Inflow occurs when storm drainage is improperly piped into the sewer. Infiltration occurs when cracks or other defects in the sewer mains allow groundwater to enter. Unwanted storm drainage and groundwater flow into the sewer which increases risk of sewage overflows and unnecessarily increases the volume of wastewater treated at the treatment plant, ultimately increasing ratepayer costs. Based on the smoke testing, seven sources of inflow have been identified commonly from stormwater catch basins. A capital improvement project will need to be carried out to address the problem. The project consists of disconnecting known sources of stormwater inflow from the sanitary sewer system, along with the improvements necessary to remove these sources.
Wallis Engineering was chosen for design services to disconnect the inflow sources and properly connect them to the storm system. The services include surveying, field explorations of site conditions, evaluation of alternative co...
Click here for full text