Installation, testing, and permitting of two new bedrock water supply wells following the loss of previous wells to drought and MtBE contamination

The Pine Grove Cooperative (Coop) experienced a water supply crisis in 2016 due to drought, resulting in one of two gravel-packed wells going dry, following the prior loss of four bedrock wells due to MtBE contamination. As a response to this urgent need for potable water, Nobis Group assisted the Coop in obtaining two new water supply sources. Nobis performed this work as a Prime Contractor to NHDES with funding provided by the MtBE Bureau and received Project Honors for the Pine Grove project from the New Hampshire chapter of ACEC.

To resolve this water supply crisis, Nobis performed the following roles for the Cooperative and NHDES:

  • Identified potential drilling sites using photolineament analysis, geologic mapping, and geophysics, including a consideration of both stratified drift and fractured bedrock aquifers on land owned by the Coop;
  • Provided well drilling and well construction oversight for stratified drift test drilling and bedrock well drilling;
  • Conducted pumping tests, monitoring, and sampling in support of a permit application to obtain NHDES approval for new bedrock water supply sources;
  • Assisted the Coop in modifying its Wellhead Protection Plan and preparing a Water Conservation Plan; and
  • Assisted the Coop in obtaining funding for the project under the Drinking Water State Revolving Fund (SRF) and the Drinking Water and Groundwater Trust Fund.

Two new bedrock wells now successfully provide water needed to make up for the shortfall in the 2016 drought and to allow for future water supply needed at “build-out”. Nobis continued to work with NHDES, the Coop, and subcontractors to connect the new wells to the water system and perform other system upgrades.

challenges

  • The Coop experienced a water supply crisis in 2016 due to drought causing one of two gravel-packed wells to run dry, along with prior loss of four bedrock supply wells due to MtBE contamination from an upgradient gas station.
  • The overburden aquifer on Coop-owned property was both limited in areal extent and by other features requiring setbacks (e.g. wetlands).
  • The new bedrock wells had to be tested and analyzed to ensure that they did not impact the Coop’s remaining gravel-packed well or nearby residential water supply wells.
  • The Coop was faced with a water supply emergency and lacked the financial resources to establish a new water supply source and perform needed water system upgrades inherited from the previous owner when the Coop formed.

solutions

  • Nobis evaluated potential water supply well locations for both bedrock and overburden aquifers. For bedrock, this assessment required consideration of a historical MtBE plume that impacted part of the bedrock aquifer and the limited accessible and suitable locations on Coop-owned property.
  • Based on the limited extent and depth of the overburden aquifer, the presence of wetlands, and the need to avoid interference with the existing gravel-packed wells, Nobis used small-diameter test drilling to evaluate potential gravel-packed well sites and rule out the option.
  • Nobis subcontracted a bedrock well driller and provided oversight for well installation and construction of three bedrock water wells. Two of these were deemed suitable for new water supply sources for the Coop.
  • Nobis subsequently designed and conducted simultaneous, staggered pumping tests on the bedrock wells that included monitoring of nearby water sources.
  • Nobis identified more than a dozen other water wells within 1,000 feet of the Coop’s new wells and sent certified letters to the property owners, offering to monitor their wells during the pumping test. Wells whose owners granted permission were monitored, showing no interference effects due to pumping the new wells.

results

  • With assistance from Nobis, the Coop successfully obtained funding under the Drinking Water State Revolving Fund (SRF) and obtained one of the first grants under the new Drinking Water and Groundwater Trust Fund.
  • Two new productive bedrock water supply wells have been sited, drilled, tested, and permitted for the Cooperative. The new wells have no trace of MtBE and show no interference with neighboring homeowner wells.
  • The yield from the new bedrock wells is sufficient to make up for lost yield from one of the gravel-packed wells during the 2016 drought and to provide water for potential additional homes at build-out.
  • In 2020, Nobis won Project Honors for the Pine Grove new well project from the New Hampshire Chapter of ACEC.