how to: pumps

system, options are available to reduce or elimi- of preventing basement flooding, the use of the the surcharged flow from the sewer, but also the nate the problem. Two key approaches include property is limited because wastewater cannot ability to pump against and overcome the pres- How to Prevent the installation of a backflow prevention valve or flow from the house to the municipal sewer sys- sures in the surcharged sewer mainline. This abil- grinder pump station. tem. A grinder pump system provides pressurized ity to pump against a surcharged sewer allows A backflow prevention valve can provide some flow. This solution provides a positive isolation of for uninterrupted use of fixtures and Basement Floods protection against basement flooding due to sur- wastewater-generating appliances. charged sewers. Backflow prevention valves can be mechanical gate-type valves, or check/flap- 3 Implement the Solution Using Grinder Pumps per-type valves. The objective of a backflow pre- Grinder pump stations are integral units that vention valve is to provide a physical barrier in the consist of a basin, controls, piping (including a private sewer service lateral and prevent waste- shutoff valve and check valve), and a semi-pos- water from backflowing and flooding basements. itive displacement grinder pump. The grinder Backflow prevention valves, by design, are pump station collects all of the wastewater from closed during sewer surcharge conditions to the home. When wastewater in the tank reaches prevent wastewater from entering the home. a certain level, the pump turns on automatically, When the valve is activated in the closed posi- grinds the waste into a fine slurry, and discharges tion, plumbing fixtures should not be used. it under pressure into a small-diameter that Wastewater generated within the household can- flows to the existing sewer main. Because the dis- not flow out through a closed valve. Continued charge pressure produced by a semi-positive dis- use of fixtures and wastewater-generating appli- placement grinder pump is greater than the back ances can result in flooding from the wastewater pressure in the surcharged sewer, the wastewater generated within the building. flow from the property to the municipal sewer not Backflow prevention valves need to be installed only is ensured, but any backflow into the base- properly and require regular inspection and main- ment is prevented. tenance to remove debris and provide some The grinder pump system can be installed in the insurance of protection against failure. When a property’s basement or yard. Certified installation valve fails to close completely, the device slows of the system is recommended. The whole-house down the surcharged flow of wastewater, but grinder pump station is a dependable and cost- does not stop it completely. effective solution to prevent basement flooding Grinder pump stations provide a reliable and caused by surcharged sewer systems. operationally superior solution to prevent base- ment flooding due to sewer system surcharges. Keith McHale, P.E., is I&I project manager for While a properly installed and operating backflow Environment One Corp. McHale can be reached prevention valve can provide limited assurance at [email protected].

By Keith McHale n many communities, basement flooding and other debris, or pipe collapse prevent the is a rite of spring. Snowmelt and heavy normal free flow of wastewater from the home. spring rainfall often lead to flooded base- Basement flooding because of service lateral A three-step approach ments. Basement flooding, however, can blockages typically is the responsibility of the occur throughout the year. There are numer- homeowner and often can be remedied by clean- ALLOW ME TO INTRODUCE MYSELF . . . to minimizing ous reasons some basements flood, and ing the service lateral, and in extreme cases, steps can be taken to minimize, if not completely replacing part or all of the service lateral. or eliminating eliminate, the problem. Basement flooding caused by backflows from Solving problems associated with basement municipal sewers can be the most disruptive and basement flooding flooding can be simplified into a three-step approach. difficult to remedy. Flooding caused by service • Identify the source and cause of basement flooding; lateral deficiencies generally will be limited to the • Evaluate solutions to remedy the problem; and wastewater produced within the household. Minor • Implement the solution. repairs and/or changes in behavior can limit the impact. Flooding caused by deficiencies with the 1 Identify the Source & Cause municipal sewer mainline will consist of wastewater Determining the cause of basement flooding from many sources connected to the central sani- starts with identifying the source. The source can be tary or . “clean water,” such as surface storm water, or ground- systems are designed to convey water that seeps into the basement through cracks domestic and industrial wastewater to wastewater in the basement walls or foundation floor or through treatment plants. Combined sewer systems convey basement windows and doors. Although they are a a combination of sanitary wastewater and storm nuisance, clean water sources are not as serious a water. In the absence of pipe blockages, collapses or concern as “dirty water” sources. Basement flooding other physical deficiencies, overflows and basement caused by surface storm water or groundwater can flooding caused by public sewer systems typically be addressed by sealing cracks, improving site drain- occur when the volume of water in the system is age, ensuring gutters and downspouts are clean and greater than the carrying capacity of the sewer pipe. TM directing rainwater away from the home, or installing Excess water in the system can be caused by exces- I am the Insta-Valve 250 Patriot Series Insertion Valve. or repairing a foundation drain system. sive groundwater or rainwater entering the system The source of basement flooding that is of the as infiltration and inflow, or, in the case of combined greatest concern is that which is caused by back- sewer systems, insufficient capacity to properly flows from the municipal wastewater collection sys- convey the combined sanitary and wet weather tem. Wastewater backups create both a significant flow. The extraneous water can cause the sewers nuisance and a health hazard for the homeowner. to surcharge. The surcharged condition inhibits the There are a multitude of potential causes for a sewer’s ability to properly convey the wastewater wastewater collection system source of basement and can cause it to back up the private sewer service flooding. Sewer blockages that result in basement lateral and overflow into the building through floor Line Stopping  Line Tapping  Valve Insertion  Training and Support flooding can be found in the private sewer service drains and plumbing fixtures. www.hydra-stop.com 800.538.7867 lateral, but also can be the result of problems with the municipal sewer system. 2 Evaluate Solutions Service lateral blockages occur when mis- If basements are subjected to flooding aligned joints, root penetration, buildup of grease due to surcharging in the wastewater collection Write in 110

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