Water & Wastewater Treatment
Designing treatment systems to provide safe drinking water and clean wastewater effluent that often exceeds strict regulatory requirements is a core focus of our environmental engineering practice group.
Our engineers identify sustainable water supply resources and wastewater treatment solutions to meet carefully evaluated long-term demands. Our water treatment experience ranges from designing rural 100 GPM wells with chlorine disinfection to 2 MGD multi-jurisdictional super-pulsator surface treatment systems and 4 MGD reverse osmosis well systems. Our wastewater treatment experience ranges from rural secondary treatment lagoons with spray irrigation disposal to metropolitan 3.5 MGD advanced tertiary treatment systems with biological nutrient removal capabilities.
Our Work in Your Communities
New Water Treatment Plant - Martin County Regional Water and Sewer Authority
Thinking fast to lessen groundwater dependence in Martin County, NC
Depleting ground water resources have been a longstanding issue on a global level, and North Carolina has been paying particularly more attention to its resources over the last 25 years. In the late 1990’s the NC Division of Water Resources (NCDWR) began preparing updated water use regulations to mitigate water depletion due to overconsumption, which went into effect in 2002. In Eastern NC, 15 counties were affected by the new regulations, including Martin County, which was required to decrease its dependence on the Cretaceous Aquifers, by 75% no later than 2016. Facing a substantial loss, coupled with growing demands for the already depleted water resources, we helped Martin County join with other surrounding water system operators in the area to form the Martin County Regional Water and Sewer Authority (MCRWASA) and develop solutions to compensate for the decreased water source.
The resulting solution involved the study, planning and design of a new water intake and treatment plant to be fed raw water from the Roanoke River near Williamston, and delivered to the facility. Prior to this, no other water treatment plant had been designed and constructed to operate on a free flowing river so close to a salt water estuary. After extensive pilot testing and water quality analysis to prove the feasibility of the project, MCRWASA moved forward with construction of the $27 million, 2 MGD facility.
Wastewater Treatment Plant Expansion - Ahoskie, North Carolina
The first discharge to the Chowan River in 3 decades in Ahoskie, North Carolina
Winner of a 2011 Engineering Excellence Award by the American Council of Engineering Companies of North Carolina
For environmental degradation reasons, in the 1980’s the State of North Carolina eliminated the approval of surface discharges in the Chowan River Basin. Through a creative design involving the continued use of existing facilities and the construction of new treatment facilities, as well as extensive collaboration with State officials, the Town of Ahoskie was the first municipality since the 1980’s to receive permission to discharge to a tributary of the Chowan River.
The Town then turned to the expansion of its Ahoskie Wastewater Treatment Plant. The expansion included the continued use of existing land application systems and provided an additional Biological Nutrient Removal treatment system to produce effluent quality suitable for reclaimed water use, and ultimately, discharge into the Ahoskie Creek. Utilizing a Huber step screen with dewatering compactor, a vortex-type grit removal system, anaerobic, anoxic and oxic tanks, secondary clarifiers, a sludge recirculation/waste pump station, denitrification filters, UV disinfection, post aeration, a reclaimed water pump station and a reclaimed water transmission main, the plant was expanded from 0.901 MGD to 1.6 MGD capacity to provide for industries, public facilities and hospitals.
Wastewater Treatment Plant Improvements - Contentnea Metropolitan Sewerage District
Creative financing achieved top performance for the CMSD
The Contentnea Metropolitan Sewerage District operated a mid-1970s plant that served the towns of Winterville, Ayden and Grifton in North Carolina. The age of the system had left it struggling with high inflows, overflows and violations after heavy rains, and the District was placed under a Consent Order that mandated repairs and upgrades. Additionally, the plant's two-stage activated sludge process was running at its redline and enhanced nutrient removal was needed to meet the effluent limitations in the Neuse River Basin.
In developing a creative financing plan that packaged grant and loan funds to pay for the improvements, funding resources included the NC Rural Center, USDA-Rural Development, Clean Water Management Trust Fund, and Construction Grants & Loans (now NC-DWI). With financing in place, the project was addressed in two phases:
Phase 1 included a new headworks, lift pump station, deep bed denitrification, UV disinfection, post aeration tank and outfall to Contentnea Creek. Phase 2 expanded the plant's capacity to 3.5 mgd with five-stage biological nutrient removal, activated sludge process, a RAS/WAS pump station, sludge dewatering with dual screw presses and additional sludge stabilization/holding facilities.
As a result of the creatively funded solutions, CMSD is now the highest performing system among its peers with current average Total Nitrogen concentration of just .98 mg/L and average Total Phosphorous concentration of 0.14 mg/L (through the first quarter of 2016).