By Dennis F. Hallahan and Ty S. Ross
Snake River Sporting Club is a first-class golf and sporting community on 554 picturesque acres along the Snake River in Jackson Hole, WY. The area lies amid the largest intact temperate ecosystem in the United States and is closely protected by state and county agencies. It is rich in beauty and pristine. When a 71-lot residential development with an 18-hole golf course, clubhouse, and restaurant was proposed, finding a suitable and environmentally sound solution for handling the wastewater onsite was a necessity for gaining the approval to move ahead.
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| Cluster wastewater systems can easily be blended
into the landscape, since the majority of treatment
works are underground. |
The Wastewater Challenge
The rural nature of Teton County poses obstacles for wastewater treatment and disposal for all levels of development outside the town of Jackson’s municipal service area. Compliance with water quality standards set forth by federal, state, and local agencies is mandatory. The wastewater system for the Snake River Sporting Club, in particular, was subjected to additional scrutiny, due to heightened environmental sensitivity prevalent throughout the county and the project location adjacent to the Snake River. Aside from governmental regulation and public concern, efficient utilization of available space while maintaining aesthetic allure was of utmost importance to the developer.
Options Explored
Several options for wastewater collection, treatment, and disposal were evaluated for the project. Collection methods that were considered included conventional gravity, gravity with central lift stations, small diameter pressure sewer, and septic tank effluent pump (STEP) systems. The primary alternatives contemplated for treatment and disposal were individual septic systems, a community soil absorption system preceded by individual septic tanks, sand filters, and a multitude of conventional, packaged wastewater treatment systems. A pressurized STEP network terminating at a centralized community soil absorption system was finally chosen as the preferred solution. Factors affecting the decision included topographical variability, localized adverse groundwater conditions, anticipated seasonal occupancies, limited siting area within the project boundary, ease of construction, and minimal operation and maintenance (O&M) costs.
The Solution
The cluster wastewater system approach is a viable alternative that allows excellent treatment for the preservation of open space. Designing these systems with new technologies, such as subsurface chambers, allows communities and developers to meet both environmental and economic goals. Cluster wastewater systems can easily be blended into the landscape to integrate into open space view corridors since the majority of the treatment works are located underground. It was this feature, combined with the specific factors affecting the Snake River site and the location of the wastewater treatment system that made this approach an effective wastewater solution for both the sporting club owner and engineer.
Permitting—The system required issuance of a Class V, underground injection control permit from the Wyoming Department of Environmental Quality. Teton County authorities were also given the opportunity to evaluate the system design and perform inspections during construction.
System details—The community soil absorption system was designed and permitted to handle 45,000 GPD with the receiving soils having an average percolation rate of about 10 minutes per inch. Each service location has its own septic tank, providing primary wastewater treatment. Septic tank effluent is then transported via a pressurized sewer network (varying in size from 1¼ inch to 4 inches in diameter) to a 3,000-gallon siphon chamber. Isolation valves throughout the network were incorporated to facilitate system operation and maintenance and to minimize service interruption. Dual high-capacity siphon units are then utilized to dose effluent alternatively between two separate community chamber leachfields located beneath large tees on the golf course practice range. Infiltrator Quick4 Standard chambers were specified to minimize required leachfield dimensions, allowing placement entirely within the footprint of the practice tees. These chambers offer optimal installation flexibility, contouring capability, and multiple piping options that represent a dramatic evolution in the advancement of onsite treatment.
The soil absorption system was sized based on respective percolation rates at each location. For each leachfield, the chambers are configured in three equally sized, individually controlled cells measuring approximately 6,600 square feet each. One of the three cells will be rested on a yearly basis, leaving two cells operational under uniform pressurized distribution. Between the two leachfields, a total of 3,270 Quick4 Standard chambers were installed along with 624 Quick4 Standard MultiPort end caps. Effluent is distributed uniformly above the leachfield basal area through an intricate manifold/lateral system ranging in size from 1-inch to 8-inch diameter.
Two areas within the project are served by gravity sewers terminating at common septic tanks. Through the use of an Orenco Biotube filter, duplex pumping units are inserted directly within the septic tanks serving both of these locations to discharge septic tank effluent to the pressure sewer network.
The clubhouse, which generates both sanitary and kitchen wastes, has two sewer service lines. A 6-inch line carrying sanitary wastes discharges to the first of two septic tanks connected in series. A 4-inch line conveying kitchen wastes discharges to a 1,500-gallon grease-trap interceptor and is subsequently connected to the 6-inch sanitary main. Effluent is then conveyed to a separate pump chamber and the pressurized network.
Operations and Maintenance
The soil absorption system was installed in June 2006, but several components of the Snake River Sporting Club wastewater system and other associated infrastructure have yet to be completed. Final construction of all aspects is anticipated in the summer of 2007, with the wastewater system becoming operational shortly thereafter.
Little maintenance of the soil absorption will be required once placed into service. Quarterly monitoring of groundwater quality is requisite per the Class V underground injection control permit. Percolation efficiency and ponding will also be monitored via inspection ports within each cell of the individual leachfields. As noted, one of the three cells in each leachfield will be rested annually to promote biomat degradation and rejuvenation of the subsoil. Siphon cycles will also be tabulated and compared with design projections to ensure adequate disposal area and prevent overtaxing of the receiving soils.
Conclusion
The rural nature of Teton County, coupled with inherent, local environmental sensitivity, presents unique challenges when addressing isolated development and acceptable wastewater disposal. While several means of collection and treatment exist, few are suited for the aesthetic appeal requisite within a luxury golf course development. Upon extensive evaluation based on numerous criteria, a pressurized STEP network culminating at a community soil absorption field proved to be the most sensible and economical solution for the Snake River Sporting Club. Implementation of plastic leaching chambers was paramount in facilitating a seamless transition from practical wastewater disposal area to a beautifully landscaped golfing facility.
For more information about chamber solutions from Infiltrator Systems or to find out about product training, demonstrations and instructional seminars visit the company’s Web site at www.infiltratorsystems.com. Installation, educational, and technical material is also available for download.
Dennis F. Hallahan is the technical director of Infiltrator Systems Inc., based in Old Saybrook, CT. Ty S. Ross, P.E., is with the Meridian Group Inc., located in Jackson, WY.
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- January/February 2007
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