Virginia Utility Cuts Costs With Inflow/Infiltration Program
Monitoring sewer systems helped town save $775,000 over five years
The city of Manassas is helping to save on sewer treatment costs, so much so that in the past five years, it has decreased sewer flow by more than 123,000 gal per year, saving the city $775,000 as part of an aggressive inflow and infiltration program.
“Manassas utilities is in an ongoing process to review our sanitary sewer processes, making sure we’re reducing overflows, maintaining proper capacity and rehabilitating any pipes,” said Mike Moon, director of public works and utilities for the city of Manassas.“By proactively monitoring our sewer systems, we’re able to significantly save on sewer treatment costs and pass on some additional savings to our customers,” said Moon.
Customers are billed on two basic rates: distribution and a “pass through” rate for treatment costs through the Upper Occoquan Service Authority (UOSA) treatment plant. Although Manassas City’s sewer distribution rate has increased a few percentage points in the past few years, the inflow and infiltration program has helped reduce the pass-through UOSA costs paid by customers. In other words, customers’ overall rate would have increased more if the inflow and infiltration program had not been implemented.
Inflow and infiltration are terms used to describe the ways that groundwater and storm water enter a sanitary sewer system, which is a pipe located in the street that is designed to transport wastewater from sanitary fixtures like sinks, showers, bathtubs, etc. This is not to be confused with a storm sewer, which is a pipe designed to carry rainwater away. Inflow is the water that is dumped into the sewer system through improper connections, such as downspouts and groundwater sump pumps. (Sump pumps that pump only laundry water or other sanitary wastes are not a problem.) Infiltration is groundwater that enters the sewer system through leaks in the pipe.
Manassas has conducted a sanitary sewer evaluation of its system and identified areas where excessive inflow and infiltration exist, as well as operates routine inspections and testing methods, which include smoke testing, TV inspections, manhole inspections, flow monitoring, dye testing, sump pump removal and pipe replacement.
The city of Manassas suggests customers can do their part also to save on their water and sewer bill and conserve water by: checking for leaks with all sink/toilet fixtures, turning off the water after wetting your toothbrush, reducing shower time, running the dishwasher when full and consider a compost pile, rather than relying on the garbage disposal which requires water for use.