Two Drainfields Are Better Than One for a New Hampshire Shelter Facility

When the system failed at Grace House due to improper bedding sands, volunteer installing pros add a parallel Presby Enviro-Septic field as an economical and versatile solution

Two Drainfields Are Better Than One for a New Hampshire Shelter Facility

The system awaiting New Hampshire Department of Environmental Services field inspector approval for backfill.

The director of Starting Point, an organization that operates Grace House, a shelter for victims of domestic violence in Conway, New Hampshire, called me to explain the shelter’s septic system was backing up after only nine years of service. I checked it out and found the entire system of Presby Environmental Inc. (PEI) Enviro-Septic pipes was flooded. A simple test of the material surrounding the pipes using PEI’s Spec-Check field test sieves quickly indicated that the sand surrounding the pipes contained an exceptionally high amount of fines, a sure prescription for premature failure.

One option was to hook to the town sewer. This was quickly ruled out as impractical because although municipal sewer was available, it would have taken a long run across a neighbor’s property to access it. A second approach would be to remove and replace the existing disposal field. While not out of the question, this solution would involve a substantial mess and the need to dispose of contaminated soil in a safe place off the site.  


I have been a supporter of leaving an existing failed system in place and adding additional disposal area off to the side if there is room. This eliminates the mess of tearing up the original system and leaving it to restore itself by resting so it could be used again in the future. This system had worked several years and could again for short times if needed. And the open-meadow location of the original disposal area was large enough to fit another similar disposal field. 

The Starting Point board gave the go-ahead to put a plan together in late 2016, and I contacted Bob Tafuto, of Ammonoosuc Survey in Intervale, who had donated his services for the original design and agreed to do so for the additional field. The plan was quickly approved by the state.

PEI of nearby Whitefield donated all necessary Enviro-Septic components through their local distributor, Smithfield Supply of Bartlett. Alvin J. Coleman & Son of Albany agreed to donate the correct specification sand. I installed a diverter valve between the septic tank and the original field in preparation for the installation. In spring 2017, Greg Hill, of Hill Excavation, agreed to discount the daily rate for his 20-ton Case 160 excavator and his dump truck.

After Hill supervised the layout for the new system, I rototilled the area for the field and stripped the deep layer of topsoil to save it for covering the new system. Hill excavated the disposal area to a minimum of 6 inches below the bottom of the bed, and then placed a layer of specification sand to support the new Enviro-Septic pipes.

Five members of the Habitat for Humanity building crew were asked to help place the pipes and aid in backfilling. Smithfield Supply arrived with Enviro-Septic components, as well as donated 4-inch pipe and fittings necessary to hook everything up. Hill stayed to supervise the pipe installation, using his own experience as an installer to avoid mistakes and smooth the process. Walter Lancaster, certified septic evaluator, helped with leveling the bed bottom.

After the system was inspected, I backfilled the system with another layer of PEI spec sand and finally with some of the original sand, followed by the reserved topsoil. I used a small tractor with a front-mounted rake system I had developed for final grading.


Because this system features serial distribution, I also installed two monitoring points in the connecting pipes between the rows of Enviro-Septic pipes. These upward-facing capped observation tees can be used to check the flow between pipes in the future to determine how many of the system’s eight rows of pipes are in use. If water shows up in the connection to the last two pipes, the time is approaching to switch back to the original system, allowing the new system to rest. Tee locations are marked with measurements on the side of the vent pipe and with chunks of iron to verify location with a metal detector.

With the diverter valve shifting all effluent flow to the new system, the old system will enter a resting period that could mean permanent retirement or could be temporary if the new system ever proves inadequate to handle flow from the shelter. Given the old system lasted almost 10 years with inadequate bedding sand — likely the original silty sand excavated from the site and reused — and that the new system is built with sand with almost no fines, the new system should go for considerably longer.

Dual systems such as this have proven effective at providing long-term solutions for onsite disposal where one system can rest while the other is put back into use. All involved with this effort hope that this will be the case with the Grace House shelter so it can concentrate on its mission of serving the battered women of New Hampshire.


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