The Carlisle Mosquito Online

Friday, September 17, 2010

Board of Health okays one geothermal project, tables a second

The Board of Health (BOH) was asked to approve a geothermal well to be put in at 124 Fifty Acre Way at their meeting on September 7. Stephen Smith, president of GeoHydroCycle, a private consulting firm, represented the resident and the contractor.

A geothermal system uses the termperature of the ground, around 50°F, to facilitate heating a building in winter and cooling it in summer. This particular geothermal well will be an open-loop system, as opposed to a closed-loop system. In an open system, well water is used for heat exchange and then discharged. In contrast, heat exchange in a closed-loop sytem uses a long sealed loop of buried tubing, through which a water/anti-freeze mixture is recirculated. The loop may be laid out underground either vertically or horizontally.

According to, a typical home open-loop system uses four to six gallons of water per minute when in operation. However, according to BOH Agent Linda Fantasia, the water used in the proposed open-loop system will discharge back into the same well, with no net gain or loss of groundwater.

Smith explained that in an open-loop system, “at some point the fluid into and out of the well is at atmospheric pressure.” He added that while closed-loop systems may leave traces of glycol in the soil, he believed that open-loop systems are relatively clean and harmless to the environment. According to Smith, the composition of subterranean New England is particularly conducive to open-loop systems.

The installment process for this particular well will take no longer than three days and noise will be kept to a minimum.

Fantasia noted that there are already several geothermal systems in place in Carlisle. When prompted, Smith explained that nearby towns allow them as well, though many have a rigorous approval process. Currently, Carlisle has no official process in place, but it is likely that with increased demand for geothermal systems, such a process might be outlined. According to Fantasia, the previous systems approved by the board used closed-loop designs.

Other issues discussed included the depth of the well, attention to neighboring wells, the type of casing used, the necessary water quality for operation, the efficiency of the system, the potential for failure, how the well would be treated if later abandoned and the overall design of the system.

The board decided that the proposed system posed no threat to the environment or the safety of the town, and voted unanimously in favor of it. Fantasia later explained that before the system can be built, the applicant must obtain an underground injection control (UIC) registration from the Massachusetts Department of Environmental Protection.

A less successful bid

A second geothermal well proposal came before the board for 625 Rutland Street, this time for a closed-loop system. No representative was sent to the meeting to plead the case and the necessary paperwork was incomplete. In addition, Fantasia later explained that the state’s guidelines for geothermal systems had changed on August 10 and it was not clear whether the application conformed to the new guidelines. The board voted unanimously to table the proposal until proper documentation was provided, and suggested that the applicant send a representative be to the next meeting.∆

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