HARVARD — A hydrogeologic study of the Mason-Dolan land has reached a stage where more money may be needed to complete it, according to Town Center Planning Committee member Timothy Clark, who heads the group’s sewer study subcommittee.
The land is owned by the conservation trust and cited as a proposed location for a possible future sewer system for the town center.
The study — to determine if the land is biologically suited for its envisioned use — is being conducted by Environmental Partners Group (EPG), a Quincy-based firm commissioned by the committee with funds voters approved at the 2006 town meeting.
At the Aug. 15 Board of Selectmen meeting, EPG Project Manager Wayne C. Perry presented a report, sketched work in progress and outlined the proposed next steps.
A preliminary design of the envisioned system, which would tie the town center into the existing school wastewater treatment plant, calls for handling an estimated 40,000 gallons of wastewater flow per day. It would discharge into groundwater via an expanded leach field.
The Mason-Dolan land, which is near the school, might be a good location for an additional leach field, assuming it could receive up to 17,000 gallons of effluent per day.
Work at the site to date includes excavating test pits and percolation tests to see how quickly the soil absorbs water. In addition, five monitoring wells were dug, and “slug” tests were conducted at three of them to determine hydraulic conductivity. The report lists dates, purpose and test results.
In septic system terms, both good and bad soils were found on the land, and test conditions varied.
One day, Perry said, the ground water was too high to do a perk test, and only two of the five wells showed conductivity. The other three were dry.
He assigned grades to the wells. Wells 3, 4 and 5 were poor. Well 1 was excellent.
In that well, the soil consisted of fine gravel and coarse sand, he said, offering “a ray of hope” for a decent soil model. In terms of water absorption, however, the number was lower than planners had hoped for. It was 20,000 gallons a day, half of the 40,000-gallon goal.
Two or three more wells are needed for an acceptable study, he said, and it would cost a total of $6,500 to make small-diameter borings, or “geo-probes” to find soils to support those wells. An itemized list showed $3,500 for one day of boring installations, $500 for field oversight, $1,000 for hydraulic conductivity testing and $1,500 for data evaluation and status report.
The amount allocated for the project was $14,800, all of which has been paid to the company with $4,000 still on the tab. The balance Clark was seeking, then, was $2,500.
However, he said if tests show a dead-end at any point, the work would stop. The board did not OK the $6,500 ceiling. Instead it decided to limit spending to the available $4,000 on the contract, with the option of added funding if results indicate they should go farther.