Allen Decker has over 18 year’s practical experience in the wastewater industry. He has served as a wastewater operator, technical trainer and adviser with a class “A” wastewater certificate, the highest in the state of Missouri.
Prior to working with the Underground I&I division of Waterproof Solutions, he was with the premier technical assistance group in the Missouri Rural Water Association for over 11 years. As always, Allen is here to serve the industry and help in any way he can. For any questions that you may have, he is the experts expert so don’t hesitate to reach out and contact him. 314-435-5505 Inflow and infiltration (I and I) into a collection system is a condition where rainwater and ground water enter the system and overflow manholes, short circuit the waste treatment process, overload sewage lift stations, and cause sewage backups into customer homes. Inflow into the collection system is when surface water flows or ponds over the top of collection system and waste treatment equipment.
Surface waters enter the collection system through customer cleanouts, manhole lids, lamp holes, and improper installed plumbing such as restaurant grease traps. Surface water may even flow over the side of a wastewater treatment facility. Gutters and downspouts would also be covered in this category. Although many people suspect that house gutters and downspouts contribute untold gallons into the sewage collection system, improperly connected sump pumps are more common. Both are illegal customer connections. Infiltration is a condition where groundwater permeates collection system flaws underground. These flaws include cracked pipes and bad joints in sewer main joints and deteriorated pump stations. Leakey customer service lines, customer perimeter drains, and driveway drains are customer repairs that are best combatted through public education and possibly system regulations.
Camera inspection services reveal flaws in the main sewer lines and service laterals. This is best done at a time when the groundwater is high and reveals only active leaks. Doing camera work without active leaks could yield marginal results at best. Conducting a smoke test on the collection system is a cheap first step. Smoke testing is a process where large amounts of smoke are pumped into the collection system.
Smoke escapes the system through flaws in the pipes and manholes. The breaks are noted, and repairs are then made to the system. This is a simple process that can be carried out by trained system personnel. Installing flow recorders help to narrow down the field of view in the waste collection system. These devices record the flow on a designated time table. They track low flows, high flows, when they flows increase compared to rain amounts and duration, how long after the rain subsides, and monitor 24 hours a day/ seven days a week. They take time to gather data. The data is only as good as the thoroughness of the analysis and strategic placement of the equipment. Still one of the best and most effective methods of locating sources of I and I are by opening manholes one at a time, in both dry and wet periods.
The manholes themselves contribute over one third of excess flows and unnecessarily burden on the system. Many needless repairs are made by even the best educated guess. A look at “Value Engineering” should yield the best results. Value engineering is systematic method to improve the “value” of goods or products and services by using an examination of function. Value, as defined, is the ratio of function to cost. Value can therefore be increased by either improving the function or reducing the cost.
