Sustainable Land Development Today - September 2007 - (Page 35)

WASTEWATER Many Challenges Determine Sewer Options Wassamassaw Plantation subdivision succeeds with decentralized system. By Bryan Kizer, P.E., Frank Iwanicki, P.E., and John Thorpe Wassamassaw Plantation is a 352-acre gated community located just 25 miles northwest of beautiful downtown Charleston, South Carolina. This tranquil, forested neighborhood is nestled into a bluff that gently slopes into 187 acres of forested wetlands in the Wassamassaw Swamp. This botanically diverse swamp comprises a significant portion of the headwaters of the Ashley River, which flows past many of the Charleston area’s historic plantations. The developer, Wassamassaw Plantation, LLC, and the developer’s project manager, Twingate Properties, chose BP Barber to complete the conceptual layout, design, permitting, and construction oversight of this environmentally sensitive neighborhood. Due to the unavailability of sewer and inadequate soils for conventional on-site septic systems, BP Barber carefully researched and evaluated the leading engineered treatment systems. Ultimately, the Orenco AdvanTex® System was selected for this site. This refined treatment technology allowed the developer to create a beautiful 100-lot community with estate-sized lots ranging from one to 16 acres. Wassamassaw Plantation will provide some of the finest estate living in Berkley County, while minimizing the community’s impact on its pristine natural environment. Nature trails meander through this wooded setting, providing pedestrian and canoe/kayak access to picturesque cypress and tupelo swamps filled with abundant wildlife. The neighborhood also provides its residents with other amenities such as a zero entry pool, an open air pavilion, and fishing piers designed by local landscape architectural firm, Surroundingz. limiting soil layer to the ground surface, as well as various hydrologic and topographical challenges, each site required a unique wastewater disposal solution designed by BP Barber. Orenco’s AdvanTex Treatment System turns wastewater into a clear, odorless effluent with typical concentrations of BOD and Total Suspended Solids (TSS) of less than 5 mg/L each. This technology is based upon a re-circulating trickling sand filter. However, the AdvanTex Filter consists of fiberglass basin filled with an engineered textile material, rather than sand. This treated effluent is then disposed of on-site via a low-pressure subsurface drip irrigation system. This method of discharging the effluent also enables the developer to preserve most trees on site and precludes the necessity of having to construct a large community drain field, thus preserving the natural environment of the neighborhood. Historical Perspective In 2005 the South Carolina Department of Health and Environmental Control (SCDHEC) issued a new regulation that allowed the use of engineered on-site wastewater treatment systems for sites that could not be served by a conventional or modified (ultra-shallow / mound) effluent disposal field. Prior to this regulation, the mantra for subdivisions was “if it perks, it works.” Under the new SCDHEC design standard, a professionally licensed soil classifier can evaluate each lot’s soils and provide a detailed soils report to an engineer who then designs the treatment and disposal system. Land Management Group of SC, LLC, (formerly Silva Soils) evaluated the soils of every lot in Wassamassaw Plantation and characterized the project’s site as “a unique sample of the lowcountry landscape.” The terrain descends 33 feet across a distance of a half-mile, with several ephemeral streams reaching into the hillsides. This diverse topography creates a highly variable pattern of soil types, some of which are not well-suited for traditional septic drain fields. The high-quality tertiary treated effluent produced by the Orenco AdvanTex Treatment System allows for a very compact “footprint” of the drain field. BP Barber used the soils data from Land Management Group of SC, LLC, to complete the design of each Orenco system. Given the varying proximity of the zone of seasonal saturation (ZSS) and Operation and Maintenance BP Barber and the developer also required that a Home Owners Association (HOA) be created to control, operate, and maintain each of the treatment systems. The HOA has a service contract with the local Orenco distributor, Coastal Carolina Wastewater Solutions, LLC, who is also supplying the AdvanTex systems. The service contract costs are typically the same as a municipal wastewater treatment bill, approximately $30-$40 per month. When the AdvanTex treatment technology is coupled with Orenco’s VeriComm® monitoring system, it allows the wastewater operator www.LandDevelopmentToday.com 35 http://www.LandDevelopmentToday.com

Table of Contents Feed for the Digital Edition of Sustainable Land Development Today - September 2007

Sustainable Land Development Today - September 2007 Contents Our Voice: Teaching and Learning Your Voice: Reader Response Editorial Board A 52-Mile Taking Fiber to the Front Doors of America Educators Incorporating Sustainability Land Planning: The Truth about Sprawl Irrigation: Communication Key Wastewater: Many Challenges Determine Sewer Options Regulation: Changing by State, Region, and Municipality Risk Management: Construction Defect Claims Recommended Reading Products/Services Showcase Advertiser Index Calendar Classifieds The Last Word

Sustainable Land Development Today - September 2007

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