Case Studies - August 2021

Case Studies - August 2021

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Sand filter system a fit for convenience store advanced treatment unit project

Problem: A gas station and convenience store in Alabama needed a replacement system after the existing drainfield failed. There was no available space on the property, but the owners were able to acquire a small neighboring lot for sale. Soil tests showed 18 inches to the restrictive layer and had a 0.36 gpd per square foot application rate. The store uses approximately 650 gpd.

Solution: A treatment system with a reduced footprint was needed to manage the waste strength and to fit in the available space with a reserved replacement area for a future system. Eljen worked with engineer Jon Perkins to find a solution for the site. The drainfield was designed in a bed configuration, 61 feet long by 31 feet wide, with a 6-inch base of ASTM C33 sand. Ninety Geotextile Sand Filter A42 units were used, with 15 units in six rows. The system is gravity fed, and laterals are “stepped down” to follow the natural contour of the site. Effluent is routed behind the parking areas to a distribution box from the existing septic tank.

Result: The treatment system fits into the available space with room for a replacement area required by local code. The new drainfield and the remaining replacement area are protected from traffic so natural pore space in the soils won’t be compacted. 800-444-1359;

System increases oxygen levels to avoid effluent surfacing

Problem: A healthcare facility in Old Saybrook, Connecticut, had a long history of septic system performance issues. The system was repaired in 2003 with concrete chambers and began to experience problems within three years of operation, including effluent surfacing that forced the facility’s operators to pump the tank and chambers approximately three times per week. 

Solution: All potential solutions were considered, including system replacement and the addition of a tank-based aerobic treatment unit. The most cost-effective solution was to add Geomatrix’s SoilAir to the existing chambers. SoilAir increases oxygen levels to sufficiently aid in the effluent treatment process and is efficient to install and operate. In 2009, a SoilAir system was added to the existing chamber system to increase oxygen levels within the leach field. 

Result: Before the addition of SoilAir, 100% of the system was in use; after introducing air, use has fallen to 25%, and the system has not experienced any septic issues in the last decade. The system is monitored through a logic-based control system designed to react to issues before they become problems. Using SoilAir without excavation of the chambers allowed the owners to adopt a normal pumping schedule, removing the scum and sludge from the tank as needed. 860-510-0730;

Onsite system accommodates new build with stringent permit requirements

Problem: To make a proposed gas station/convenience store project a reality, Fairton and its engineering firm, ADR & Associates of Newark, Ohio, looked for a cost-efficient, sustainable and long-term solution that would be easy to operate and consistently meet the stringent permit conditions for BOD, TSS, ammonia and fecal coliforms. 

Solution: Fairton & ADR worked with Premier Tech Water and Environment to design and locally source primary reactor and equalization tanks. These are used in combination with Premier Tech’s ready-to-use polyethylene Rewatec MBBR and clarifier configuration. With the design and chosen equipment, the treatment process reduces incoming BOD and TSS strengths to low domestic levels. The process is then completed by two Ecoflo biofilters used as polishing units. 

Result: Influent numbers ultimately exceeded those in the original design. Due to the COVID-19 pandemic, the system also experienced dramatically reduced flows and dilution. Premier Tech’s team worked with the operator to make adjustments that overcame these challenges and brought the system into full compliance. The system continues to show resilience and meets original design parameters on a daily basis to ensure adherence to permit conditions. 800-632-6356; 


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