Following thorough review of the project, Sani-Plant of Trujillo Alto, PR selected Presby Environmental’s NSF 40 and BNQ Certified, Advanced Enviro-Septic®(AES) combined treatment and dispersal system. A 6,000 GPD system was designed with an additional septic tank that included a Presby Maze septic insert to increase the reten - tion of the waste to allow greater efficiency in the primary treatment. Because of the AES system’s rigorously tested capability for high level treatment, the system needed a treatment and dispersal footprint of only 5,609 ft2 (39 ½ ft x 142 ft) with an application rate of 1.07 gpd/ ft2. Also, the project required only 2,600 feet of AES pipe in a but - terfly configuration with eight serial sections. This saved the facility a significant amount of space. Additionally, by installing a passive CTD system with a proven record for exceeding required treatment levels and a reduced footprint, the Víctor Hernández Building saved significant short and long-term costs. Other Large-Scale Applications for Passive, Sand-Lined Treatment Systems The reliable, consistent, high level treatment capability of these pas - sive sand-lined systems can be applied to other applications which may require mechanical processes to augment the performance of these systems. For example, adding mechanical pretreatment to these technologies creates increased reliability of the redundant treatment processes. Redundant treatment may also be desired to deal with the challenges of high strength effluent applications, where one treatment system reduces the strength to manageable levels for the subsequent treatment system. Another option for these passive, sand-lined treatment systems is to collect the treated effluent by placing the treatment field within a liner allowing subsequent, possibly mechanical, processes such as recircula - tion and/or ultra-violet disinfection. Application in Action Innovative Upgrade of Community’s Municipal Wastewater Treatment Plant Incorporates Recirculation for Denitrification at Blodgett Land - ing, Newbury, NH Originally designed in 1959 as a seasonal wastewater treatment facil - ity (WWTF) for a lakeside community in Newbury, New Hampshire, the 50,000 gallon per day (GPD) Blodgett Landing WWTF was not equipped to meet the treatment requirements of the 21st century. As the population grew and residences were converted to year-round use, effluent testing and groundwater monitoring confirmed nitrate concentrations were a growing problem. Following a successful pilot study to explore collecting a portion of the treated effluent to recircu - late through the sludge layer of the existing 34,000-gallon Imhoff tank to facilitate denitrification, plans were made to incorporate denitrifica - tion into the planned upgrade to the treatment plant. Project engineers recommended incorporating Enviro-Septic tech - nology from Presby Environmental into the existing sand filter con - figuration, to enhance aerobic nitrification and allow for increased denitrification in the recirculation process. The passive treatment performance of the Enviro-Septic technology utilizes the naturally
occurring bacterial process eliminating the need for added chemicals, biological additives, or electrical energy. Its subsurface configuration and low maintenance requirements are desirable for any community. For Newbury, this innovative approach allowed the rehabilitation and continued use of the existing Imhoff tank and sand filter/RIBs resulting in construction cost savings. The upgraded Blodgett Landing WWTF has been operating for over eight years with very consistent results. The Enviro-Septic technology allows the Blodgett Landing Facility to significantly reduce certain wastewater contaminants including Fecal Coliform, Total Nitrogen (TN), 5-day Biochemical Oxygen Demand (BOD5), and Total Sus - pended Solids (TSS). Conclusion Septic system designers, engineers, and developers should consider making room in their toolbox for the simple, reliable, problem-solving capability of passive, sand-lined wastewater treatment technologies. These technologies have been successfully applied to wide-ranging wastewater treatment system applications for the past 30 years. Easily scalable for residential, municipal, and industrial-sized systems, these passive CTD systems can be applied to solve wastewater treatment challenges that meet the various stringent regulatory and environmen - tal challenges facing wastewater professionals today.
DONALD PRINCE is Technical Advisor at Presby Environmental, Inc. He holds a Civil Engineering Degree from Vermont Technical College and is a licensed septic system designer and evaluator. He has provided technical support for AES and other Presby Environmental products since 2012. Presby Environmental is an Infiltrator Water Technologies company. Don lives with his family in northern Vermont. He can be contacted at Don.prince@presbyeco.com.
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