The City of Peshtigo has experienced recent sewer system overflow events that have been partly due to high wet weather flows. It was decided to perform a smoke testing program as part of the City’s sewer system evaluation survey (SSES). The smoke testing program was performed over a 3-day period in the wastewater collection system west of the Peshtigo River in August of 2017.
The purpose of the smoke testing program was to identify sources of infiltration and inflow (I/I) in the sanitary sewer system. The program was performed by blowing smoke through the sanitary sewer from 74 manholes in the system.
Prior to the fieldwork, letter notices were sent by the City to all properties in the study area and a notice was published in the City’s official newspaper. Door hanger notices were distributed 3 to 4 days prior to the smoke testing. These notices informed residents and property owners of the purpose of the smoke testing program and provided information on ways to prevent smoke from entering buildings. An inspector was with any confined residents during the testing in their area.
Coverage of the tested area required a number of inspectors. The City provided 8 staff members for the program. Ruekert & Mielke, Inc. (R/M) provided a smoke blower operator and program manager, along with a training program for the City staff 2 weeks before the fieldwork.
The smoke testing program identified 42 sources of I/I. Smoke was observed coming from: 3 buildings with roof drains connected to the sanitary sewer system; 17 broken cleanouts; 9 uncapped cleanouts; 2 storm sewer catch basin cross connections; an abandoned building with failed foundation walls; and manholes with pick-hole lids.
R/M provided a summary report to the City and proposed draft correction letters for the City to use in eliminating the sources of I/I. The City’s goals of reducing clearwater flows were effectively achieved at a much lower cost than other SSES programs.
About the Authors
Taryn S. Nall, P.E.
Taryn has over 40 years of experience in planning, design and construction of water, wastewater, and storm water facilities. Taryn has significant experience evaluating the condition of storm and wastewater collection facilities, developing design flows, and determining the most cost-effective rehabilitation plans.