Case Studies - April 2021

Case Studies - April 2021

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Extended aeration units solve challenge at resort

Problem: The Lauloa Ma’alaea Resort in Hawaii was required to update its wastewater treatment unit due to tighter effluent requirements required in a forthcoming permit update. The existing treatment unit was installed below grade in the resort’s parking lot. Due to limited space on the site, this was also the only possible location for a new system. 

Solution: To meet the new regulation requirements and handle the design flow of 21,000 gpd, the resort selected a Delta Extended Aeration Treatment Unit. The old treatment unit was removed from the site, followed by the placement of a foundation on which the new treatment system was installed. To ensure the treatment unit was out of sight, secure and aesthetically pleasing, a building was built around the unit. The extended aeration process selected for this system utilizes aeration followed by clarification and disinfection. The flow equalization chamber receives incoming wastewater, and then duplex pumps discharge the wastewater into the aeration chamber. A duplex positive displacement blower and distribution manifold system supplies all the air needs to the system including air diffusers, airlift pumps and a scum skimmer. The influent characteristics were typical domestic waste loadings, with effluent requirements of less than 20 mg/L BOD/TSS.

Result: Installation of the factory-built ATU went smoothly and the system is performing as expected. 800-219-9183;

System eliminates biomat clogging issue

Problem: A Connecticut convenience store had long dealt with failures in its leachfield receiving high-strength wastewater. The existing system contained a septic tank, grease trap and two concrete chamber leachfields. Both had experienced failures within 12 years of installation and required frequent pumpouts. 

Solution: In 2017, Geomatrix was engaged to investigate. Analysis determined the failures were due to high-strength wastewater biomat clogging. A SoilAir system was installed to rejuvenate the existing chambers and handle the future high-strength wastewater flows. This solution eliminated the need to excavate, repair or replace the existing chamber systems, which were intertwined with the fuel dispensers, piping, tanks and parking, all directly in front of the store. The direct and indirect costs of disturbing the fuel system would have been many times the cost of the septic system. Construction took less than a week, and store traffic was not impacted. 

Result: For three years, the system has operated utilizing less than 50% of the leaching capacity. Geomatrix continues to remotely monitor the system through a logic-based control system that can react to issues before they become problems. 860-510-0730;

Treatment system used to moderate flow within limits

Problem: Registered sanitarian Jon Maass of JMI OSSF Consulting was contracted to help with a challenging mixed-use site of an office complex serving more than 300 people and a culinary training facility with corporate housing/condos for trainees in Dripping Springs, Texas. When all the uses of the property were added up, they were looking at 5,400 gpd flow on weekdays, with just the condos on the weekends at 2,700 gpd. In Texas, systems discharging more than 5,000 gpd aren’t permitted at the local level under TAC 285. State permits can take up to a year to obtain and at much greater expense in both equipment and permit/design fees, and this site was well under construction and expected to be occupied within six months. 

Solution: Working with the sanitarian, Hoot Systems devised a plan to provide additional flow equalization and stack the excess waste generated Monday through Friday, adding this to the weekend flows to utilize the entire week’s capacity limits. The flows from the condos were residential strength, however the office building and training kitchen generate higher strength waste. This combined flow required a 12,500 gpd MTS treatment system to properly treat the waste stream.

Result: Technicians from Hill Country Wastewater were able to get the system installed on budget and in time for the grand opening and are the current operators. The daily flow to the drainfield has kept at or below 4,800 gpd and is in compliance with the TAC 285. 888-878-4668;

Pretreatment system used for high FOG wastewater

Problem: The Cottage Hotel is a historic tavern and restaurant at the center of town in Mendon, New York. The one-third acre parcel presents major challenges for a septic system, as space at the site is mostly limited to the footprint of the buildings and parking. Wastewater is treated and then discharged into a nearby stream. Pretreatment had historically been accomplished through an aerobic treatment unit with polishing through a single-pass sand filter with SPDES-permitted surface discharge. Although the ATU and sand filter are good treatment technologies, at this particular site, the fats, oils and greases generated from the kitchen waste were too much for the system to handle, causing the sand filter to clog routinely. Regulatory authorities mandated the failing system be upgraded to be better suited for handling the high strength of commercial wastewater. 

Solution: The owner hired Onsite Engineering to design a commercial septic system to handle the high strength restaurant wastewater — and treat it to the high level needed for a permitted surface water discharge. The redesigned system uses the White Knight Microbial Inoculator Generator from Knight Treatment Systems. The system inoculates and pretreats the wastewater with select bacteria that aggressively digest the FOG and other organic constituents prior to passing through the rebuilt single pass sand filter. 

Result: The system has been working well since its 2017 installation. 800-560-2454;

System a fit for tight space and high-water table

Problem: The owners of the Bald Eagle Golf Course in Washington State wanted to develop a condominium complex that required onsite treatment and dispersal. The two challenges for this project were lack of area and the results of the groundwater mounding analysis. The area available for dispersal had enough soil for a standard subsurface drip system, but a groundwater mounding analysis determined the winter water table would not provide enough vertical separation. 

Solution: A determination was made to use the OSCAR system from Lowridge Onsite Technologies. The OSCAR can be installed at-grade, so all of the soil profile can be used to determine vertical separation. This meant there was enough area and vertical separation for the project to be approved. The project was broken up into three 3,500-gpd segments. Each segment had two zones, each at either 1,700 or 1,800 gpd. Because of regulatory requirements, each zone had an upslope curtain drain, a 10-foot downslope setback to the OSCAR primary, and adjacent reserve area, and then a 30-foot setback to the next curtain drain. 

Result: Even with the 30-foot setback for each of the zones, the OSCAR technology required less space than the next best option. The system allowed for the development of the complex. 877-476-8823;

National park service research station uses combined treatment and dispersal system to protect sensitive environment

Problem: An upgrade of the existing, inadequate potable water and onsite sanitary sewer system was required to serve the existing lodge, houses and cabins at the University of Wyoming’s AMK Ranch research center. The center is adjacent to Jackson Lake in Grand Teton National Park and is owned by the U.S. National Park Service’s Grand Teton National Park. The new wastewater treatment system design had to comply with all federal wastewater regulations for national parks and had to preserve the pristine Jackson Lake environment. Additionally, solution had to be compatible with the extreme cold and frost depths prevalent in area winters.

Solution: A 6,500 gpd combined treatment and dispersal Advanced Enviro-Septic (AES) system from Presby Environmental with 3,120 linear feet of AES pipe was specified because it removes up to 99% of wastewater contaminants without using electricity or replacement media. The depth of allowable cover over the system was a contributing factor in the selection of the system, given the extreme winter conditions. Construction of the new system could only begin once the AMK Ranch was closed for the season and it needed to be completely operational for the 2020 season. 

Result: Materials were delivered by Ferguson Water Works, which provided the AES Pipe. The small footprint of the passive AES system as compared to conventional wastewater treatment systems resulted in minimal impact and disturbance of the site during installation. 800-473-5298; 


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