Case Studies: Distribution Equipment and Systems

Decentralized effluent sewer provides onsite solution

Problem: Located along Norris Lake and adjacent to the Chuck Swan Forest & Wildlife Management Area in Union County, Tennessee, the Sunset Bay residential community had a challenging wastewater problem. The development’s 1,000-acre waterfront location, tight lot sizes, and complex, hilly terrain meant traditional septic systems and drainfields would not work. The closest treatment plant was 20 miles away in Maynardville, so connecting to it wasn’t an option. Many of Sunset Bay’s residents lived there seasonally, so flow rates across the 750-home subdivision were highly variable. To add to the challenge, the Tennessee Department of Environment and Conservation applied stringent discharge limits on the project — including a maximum of 20 mg/L nitrate — because of its environmentally sensitive locale.

Solution: Sunset Bay developers TN Emmons LLC turned to distributor Specialized Operations Services and engineers Environmental Systems Corporation for a cost-effective solution that would meet TDEC’s requirements. Ultimately, Orenco Systems proposed and TDEC approved a decentralized effluent sewer that used individual on-lot advanced treatment systems, AdvanTex AX20s or AX20-RTs, followed by low-pressure sewer lines to convey the highly treated effluent to equalization tanks before final dispersal into a 41,400-linear-foot drip field serving the entire community.

Result: In the end, the system, which is operated by HPUD, has a design capacity of 165,000 gpd and is outperforming all permit requirements. In fact, the on-lot units average 4.7 mg BOD, 3.0 mg TSS, and 9.0 mg nitrate, far better than TDEC’s maximum requirements — and they achieve this nitrogen reduction with no supplemental additions of carbon or alkalinity. 800-348-9843; www.orenco.com

Submersible solids-handling pump helps protect town

Problem: The County Home Lift Station operated by the town of Danville (Indiana) Wastewater Department sits downstream from a hospital, jail and landfill. Clothing, needles, toothbrushes and other debris from these facilities repeatedly clogged the station’s three pumps, driving up costs and hindering productivity. Staff at the Danville Wastewater Department were facing rising service costs and losses in productivity due to frequent emergency unclogging with vacuum trucks and manual clearance of debris.

Solution: The town chose a Pentair Hydromatic next-generation submersible pump, which uses a semi-open stainless steel impeller and self-cleaning cutter plate to eliminate tough clogs. The oil-filled, premium efficient motor reduces energy use and lengthens pump life. BBC Plumbing worked with Danville Wastewater to initiate a 90-day trial period, replacing one of the three pumps at the station with a Hydromatic Next-Gen Submersible.

Result: At the first inspection, personnel noticed that the wet well was significantly cleaner with less trash and debris. “It does so much work for the other two pumps,” says Wayne Herring, wastewater operator. “There’s less trash at our facility. We’re not clogging up.” At the conclusion of the 90-day trial, the pump had passed over 17 million gallons of wastewater, experiencing zero clogs. The Danville team was so impressed with the pump’s performance and reliability, they opted to purchase the trial pump and to replace the other two pumps at the station with Next-Gen models. 763-545-1730; www.pentair.com