ADS Environmental Services services

Collection system capacity will continue to be of paramount importance to municipalities. Increasing population growth, peak wet weather infiltration/inflow and pipeline deterioration all affect the ability of the collection system to properly transport wastewater flow. Inadequate capacity results in Sanitary Sewer Overflows (SSOs) across the country with subsequent Federal and State regulatory actions.

Usually performed in conjunction with internal TV inspections. Dye Water Flooding aides in the location and quantification of specific defects during an evaluation. The procedure consists of forcing non-toxic dye into defects located during smoke testing and manhole inspection. The path of the dye is then documented, and leaks in the sewer lines are located. Manholes with evidence of inflow/infiltration, mainline defects, cross-connections, roof drains and area drains can all be investigated using the dye flooding procedure.

Flow isolation is performed in sewer lines where groundwater has been determined to enter the sanitary sewer in significant quantities. Isolation of ground water is undertaken during the early morning hours (midnight to 6am) when residential usage is at a minimum. Portable pipe weirs are placed in the targeted sewer lines to measure the flow in micro-systems of approximately 10,000 linear feet. The gallons per day per inch-diameter-mile (idm) is calculated in order to isolate the areas contributing significant infiltration. In coastal cities and where ground water levels are high, flow isolation can be a very effective tool in locating extraneous flow.

Flow monitoring is used to determine the hydraulic conditions of sanitary sewers under various conditions. Typically conducted over a 60-day period, temporary flow monitoring can be used to determine inflow/infiltration levels, calibrate dynamic hydraulic models, measure in-situ line capacity and detect bottlenecks within the system. Longer duration permanent flow monitoring networks can act as billing stations and can help cities and industries pro-actively manage their wastewater collection systems.

Inflow/infiltration is a parasite that robs the collection system of capacity. It is also an indicator of the condition of the sewer system. High inflow/infiltration is associated with system deterioration. By using inflow/infiltration as an indicator, the public works staff can evaluate its rehabilitation program. It is significantly less expensive to rehabilitate a sewer system than to replace it.

A manhole inspection is performed in order to accurately inventory the assets of the collection system, to update collection system maps and to determine the structural condition of each manhole. During manhole inspection, ADS Environmental Service"s field crews take a complete inventory of each manhole including construction materials, ring size, depth to invert, flow conditions and evidence of surcharge. All inventory information is recorded in the project database and can be used to develop maintenance and repair programs. ADS also uses digital camera equipment during manhole inspection to document defects that may be discovered.

Accurate maps of the sanitary sewer system are critical to the success of maintenance or sewer system evaluation programs. Map correction can provide updated information regarding line and manhole placement and may also locate manholes that could not previously be found. As part of an overall system evaluation program, a client"s manhole numbering system will be used. If there is not a system already in place, ADS Environmental Services will develop one. The manhole numbering system is used to aide in documentation of system defects in the project database. ADS" database for manhole asset inventory and management is Microsoft Access, which allows export into popular GIS and desktop mapping (DTM) systems.

Smoke testing will identify inflow sources and most restrictive conditions within the sewer lines. In order to identify defects in the lines, the non-toxic smoke will be forced into the sewer. During the smoke test, breaks in the sewer will allow the smoke to escape. Ordinarily, one line segment upstream and downstream of the manhole will be tested at one time.