The 1996 Safe Drinking Water Act (SDWA) amendments required states to implement a Source Water Assessment Program (SWAP). As part of this program, the states were required to delineate protection areas for public surface and groundwater sources. Each state was to inventory land uses in these source protection areas, determine their susceptibility to contamination, and inform the public of the results. In implementing the SWAP project, the Department of Environmental Protection (DEP) compiled detailed information on potential threats to public water supply sources, including but not limited to 21E disposal sites. DEP expects these susceptibility determinations for Massachusetts to be completed by June 2004.
SWAP Program Summary
The SWAP project evaluates source susceptibility and protection, monitoring, maintenance, and treatment activities, and makes recommendations for improvement, if necessary. As part of the SWAP process, DEP identified Zones A, B, and C for surface water sources and Zones I, II, and III for groundwater sources, to provide the best possible estimation of a source's recharge area. As the result of this effort, 228 Interim Wellhead Protection Areas (IWPA) for community water supply wells were replaced with DEP-approved Zone II delineations.
Zone I, Zone II, Zone III and Interim Wellhead Protection Areas
In 1984, DEP began identifying Wellhead Protection Areas (WHPAs) for all potable public groundwater sources. The WHPA process identifies three separate zones for each source:
- Zone I is defined as the area encompassing a maximum 400-foot radius around the wellhead (assuming a greater than 100,000 gpd withdrawal rate).
- Zone II is defined as the entire extent of the aquifer deposits that could fall within, and upgradient from, the production well's capture zone based on the predicted drawdown after 180-day drought conditions at the approved pumping rate.
- Interim Wellhead Protection Area is defined as the area encompassing a half mile radius around a public supply well that does not have a delineated Zone II.
- Zone III is defined as the entire watershed upgradient of Zone II.
SWAP and the 21E Program
Implementing the SWAP Zone II delineation project may directly affect the way DEP and the regulated community characterizes, manages, and remediates 21E sites in Massachusetts. Following Zone II delineation, some sites will no longer be required to meet GW-1 cleanup standards. Such sites may require less remedial action, and therefore cleanup costs may be reduced. However, DEP anticipates that many sites will require additional response actions to meet applicable MCP requirements that are triggered by Zone II delineations. A preliminary list of issues that may apply to 21E sites is presented below.
Whether someone must notify DEP of a release depends on the notification thresholds in effect at the time the sample is collected. In newly delineated Zone IIs where the Reportable Concentration GW-1 (RCGW-1) notification standards apply, DEP will not require retroactive notification for sites based on historical data. However, if additional data collected after the relevant Zone II delineation indicate that a release has occurred above RCGW-1 standards, then the notification requirement will be triggered.
Sites in the 21E System
21E sites located in Zone IIs that have not achieved Class A or B Response Action Outcomes (RAOs) before the effective date of a relevant Zone II delineations will be required to meet the applicable Groundwater - 1 (GW-1) cleanup standards. Licensed Site Professionals (LSPs) and Potentially Responsible Parties (PRPs) may need to determine if changes are necessary to comply with the applicable GW-1 standards. The list below presents some issues that may need to be addressed.
Permit and Tier Classification Issues
Due to the nature of the local geology, Zone IIs are irregularly shaped. LSPs with sites in or near public supply wells that were selected for Zone II delineation under this project should locate these sites in relation to the newly delineated Zone IIs to determine if the following MCP requirements apply:
- Sites within Zone IIs with concentrations of Oil or Hazardous Material (OHM) greater than RCGW-1 standards are categorically classified as Tier I (310 CMR 40.0520(2)(a)(1)).
- Sites located within newly delineated Zone IIs should re-score and may be required to file a Major Permit Modification. In addition, Tier II sites located within the newly delineated Zone IIs will be categorically classified as Tier I sites (based on the inclusionary criteria), requiring Major Permit Modifications.
- Sites previously located within IWPAs but now outside delineated Zone IIs may elect to re-classify and possibly achieve Tier II status. In addition these sites may have the opportunity to meet less stringent cleanup standards.
- Annual Compliance Fees may be affected by changes in Tier classification and permit category status.
If a site is undergoing a Release Abatement Measure (RAM) or Immediate Response Action (IRA), to achieve an RAO before the one-year deadline, or is conducting Phase II through V activities after Tier classification, additional assessment and/or remedial actions may be required to achieve GW-1 standards instead of GW-2 and/or GW-3 standards.
Post RAO Sites
Sites that have achieved permanent solutions but could not achieve background concentrations (Class A2, A3, A4, B2, and B3 RAOs) may be located within areas that are subsequently delineated as Zone IIs. Therefore, concentrations of OHM may exist in Zone II areas in excess of Method 1 GW-1 groundwater standards. However, to be consistent with the "liability end point" after RAOs are submitted, sites that have submitted RAOs with Permanent Solutions (Class A or B RAOs) will not be required to initiate additional remedial action to comply with newly implemented Zone II delineations unless the RAOs are not protective for eliminating current or foreseeable exposures associated with previously identified IWPAs, as described in 310 CMR 40.0900 and 40.1000. However, sites that have previously achieved only temporary solutions (Class C RAO), and are located within Zone IIs, must meet GW-1 cleanup criteria before submitting a Class A or B RAO.
DEP's Bureau of Waste Site Cleanup (BWSC) and the Drinking Water Program (DWP) have coordinated communication efforts on changes in IWPA/Zone II status for specific water supply wells so the regulated community and the public can access information concerning these new delineations. For purposes of determining the standards applicable to an RAO, the official effective date will be the date the DWP sends the water supplier an official notification letter. Lists by region of the Zone II delineations approved through this program by town and source identification number are available on the Source Water Protection for Drinking Water Supplies web pages.
The MASSGIS Wellhead Protection Areas datalayer has been updated to reflect these Zone IIs. Hard copies of the specific Zone II maps are available for review in DEP's regional and Boston offices. The regulated community and the public can obtain the Zone II data layers via the Internet from MASSGIS. In addition, information can be obtained from the SWAP Zone II delineation contact, Joe Cerutti, at (617) 292-5859.
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