Wauwatosa Lateral Rehabilitation Pilot Project

The City of Wauwatosa, Wisconsin (Wauwatosa) conducted a lateral rehabilitation pilot project to help Wauwatosa decide how best to use available funding for Infiltration/Inflow (I/I) reduction efforts. This pilot project was configured to answer three questions:Can significant I/I reduction be achieved by rehabilitating only the portion of laterals in the public right-of-way (ROW)?Can significant I/I reduction be achieved by targeting only the leakiest laterals for rehabilitation?What residual amount of I/I will remain after lateral rehabilitation?The pilot project occurred in two focus areas that had been identified to have high I/I rates. In one area selected laterals with the highest leakage rates were lined with Cured-In-Place (CIP) liner in one round of rehabilitation. Later, the remaining laterals were lined. In the other area all laterals were lined in the ROW to evaluate the effectiveness of lining just the lower section of the laterals. Rainfall simulation tests were performed after each phase of rehabilitation to measure the effectiveness of each round of rehabilitation for reducing I/I.The I/I rates decreased for each round of testing, with the lowest I/I after the comprehensive rehabilitation. The cumulative flows, averaged over all of the properties in the study areas, were approximately three to four gallons per minute (gpm) per lateral before rehabilitation. After rehabilitation the average lateral flow rate was reduced to approximately one gpm per lateral.