Monitoring Effectiveness of Sump Pump on Reducing Private Infiltration/Inflow

City of Columbus, Ohio has chosen a source control approach to solve wet weather sanitary sewer overflow problems and achieve Ohio EPA consent decree requirements. The source control approach includes lining private sanitary laterals, redirecting roof downspouts to streets, and installing voluntary sump pumps in residential homes. Past studies and monitoring have demonstrated the effectiveness of lateral lining on reducing private source infiltration/inflow (I/I), however not sufficient monitoring has been performed on effectiveness of sump pump. Prior to implementing the sump pump program in full scale, City of Columbus conducted a pilot project of 118 sump pump installation with 25 sump pumps being monitored for over 18-months since November 2016. The monitoring program is to quantify peak I/I reduction and explore ways to improve sump pump effectiveness. The monitoring program includes time-stamped depth sensors in sump pits, water meters on sump pump discharge pipes and flow meters in sanitary sewer mainline.This paper analyzes the peak I/I reduction of sump pump for 10 storms ranging from 2-month to 25-yr rainfall intensity and volume. Standard (22’’) sump pits and deeper (30’’) sump pits were compared to demonstrated that higher I/I reduction effectiveness can be achieved with deeper sump pits. The time-stamped level data along with sanitary mainline flow meter data showed sump pump could reduce peak I/I rate by up to 7 gallon per minute per sump pump. The average peak I/I reduction rate is 1-2 gallon per minute per sump pump. Given 25% of homes with sump pumps installed, a peak I/I reduction average rate of 3-10% can be achieved.