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New Groundwater Sources

A new groundwater source for public water supply is water located within the saturated zone (below the water table) that is available to supply wells and springs and not covered by a valid DEP-issued permit.

The permitting process for new groundwater sources includes a sequence of steps that must be completed by the PWS and their Pennsylvania-licensed professional geologist (professional geologist). The steps include a pre-aquifer test component, aquifer testing, and post-test activities (Hydrogeologic Report and Module 3A). Some sources may need to be evaluated for groundwater under the direct influence of surface water. Successful completion of each step ensures:

  1. Compliance with the Rules and Regulations at 25 Pa. Code § 109.503
  2. Resources are spent on a high-quality source
  3. A complete permit application package that includes data needed to evaluate the source

In addition to other applicable requirements, the permit application package for a new groundwater source must include the following information:

  1. A Hydrogeologic Report
  2. A completed version of Module 3A: Groundwater Sources (3900-PM-BSDW0254D)

Projects involving groundwater withdrawal may be subject to review and approval by the Delaware River Basin Commissionor the Susquehanna River Basin Commission. The PWS must contact the appropriate agency to determine applicability of regulations that may be required as part of their project.

Aquifer Test Program

The aquifer test program for permitting a new groundwater source for public water supply includes a pre-aquifer test component, aquifer testing, and completion of a Hydrogeologic Report. Each part of the aquifer test program is described below.

Pre-aquifer Test Component

The pre-aquifer test component (Aquifer Test Application) consists of a sequence of steps summarized on the flowchart provided below. The steps include a combination of field and office work executed by the PWS and their professional geologist. Successful completion of the pre-aquifer test component ensures that resources are spent on constructing a high-quality source and that the aquifer test program results in data needed to evaluate the sustainability of source. Further details can be found in DEP’s Aquifer Test Application (3900-FM-BSDW0022).

Aquifer Testing

After the pre-aquifer test component is completed, the PWS and their professional geologist execute the aquifer test. A complete aquifer test consists of four individual components (listed below). Successful completion of each component ensures that the Hydrogeologic Report submitted with the permit application package will include data needed to evaluate the proposed source. Further details can be found in DEP’s Aquifer Testing Guidance for Public Water Systems (394-2125-001).

Aquifer Testing Components:

  1. Step test
  2. Background test
  3. Constant-rate aquifer test and water-quality sampling (new source sampling)
  4. Recovery test

Each component of the aquifer test should be scheduled to avoid heavy rain events or subsequent rapid changes in water-table elevation and conducted during a period of recession when local stream flow conditions are at or below seasonal averages. Prior to conducting the constant-rate aquifer test, two-week advance notification must be given to the DEP Regional Hydrogeologist.

Hydrogeologic Report

As part of a complete permit application package for a new groundwater source, a Hydrogeologic Report, signed and sealed by a professional geologist, is required. The report must include an analysis and interpretation of data collected from the aquifer test and other information describing the groundwater source. Further details can be found in DEP’s Aquifer Testing Guidance for Public Water Systems (394-2125-001). Specifically, the Hydrogeologic Report should include the following information:

  1. Geologic and Hydrogeologic Description of the Target Aquifer
  2. Construction Specifications of the Aquifer Test Monitoring Network
  3. Construction Specifications of the Proposed Well
  4. Aquifer Test Data & Sustained Yield Analysis
  5. Water Quality Assessment
  6. Project Maps & Figures
  7. Source Water Assessment

Additional Resources

A comprehensive list of DEP technical guidance documents pertaining to the hydrogeologic components of the permitting process for new groundwater sources is provided below. Technical guidance documents can be found in the DEP eLibrary.

  1. For guidance on the pre-aquifer test components, see DEP’s Aquifer Test Application (3900-FM-BSDW0022)
  2. For guidance on aquifer testing and the Hydrogeologic Report, see DEP’s Aquifer Testing Guidance for Public Water Systems (394-2125-001)
  3. For guidance on potential impacts to adjacent water resources from groundwater pumping, see DEP’s Screening Criteria on Water Quality/Quantity Impacts for Drinking Water Permits (383-2131-001)
  4. For guidance on water-quality sampling requirements (new source sampling), see DEP’s New Source Sampling Requirements for Groundwater Sources (393-3130-208)
  5. For guidance on well construction standards, see DEP’s Public Water Supply Manual - Part II Community System Design Standards (383-2125-108)
  6. For guidance on the source water assessment, see DEP’s Public Water System Source Water Assessment Form for New Community Groundwater Sources (3940-FM-BSDW0019)
  7. Public Water Supply Module 3A – Groundwater Sources (3900-PM-BSDW0254D)

Groundwater Under the Direct Influence of Surface Water

DEP must determine a representative source classification as groundwater or groundwater under the direct influence of surface water (GUDI) for all sources so that appropriate treatment techniques can be designed and constructed. For treatment purposes, GUDI sources are considered surface water and must meet the requirements as per the Surface Water Treatment Rule.

DEP evaluates new groundwater sources for GUDI prior to source approval and may reevaluate an existing permitted source at any time if there is reason to believe the source is under the direct influence of surface water. Sources may be reevaluated if there is a construction deficiency, a change in water-quality conditions, or alteration of land-use characteristics.

GUDI Defined

GUDI is the acronym for Groundwater Under the Direct Influence of Surface Water and is defined in the Pennsylvania Safe Drinking Water Regulations as any water beneath the surface of the ground with the presence of insects or other macroorganisms, algae, organic debris or large diameter pathogens such as Giardia lamblia and Cryptosporidium, or significant and relatively rapid shifts in water characteristics such as turbidity, temperature, conductivity or pH which closely correlate to climatological or surface water conditions. The term does not include finished water.

Direct surface water influence on a groundwater source (a GUDI classification) generally results from the two processes listed below:

  1. Induced recharge
  2. Direct (rapid) recharge through preferential flow paths

It is important for the PWS and their professional geologist to site, design and construct the groundwater source such that it is protected from the threat of direct surface water influence.

Evaluation Approach for GUDI

DEP uses the Surface Water Identification Protocol (SWIP) to determine if a source is GUDI. The evaluation is a multi-step process that includes (1) a preliminary evaluation that uses site-specific screening criteria to determine if a source is potentially under the direct influence of surface water, and when appropriate, (2) a specialized water-quality monitoring program that may consist of microscopic particulate analysis (MPA), bacteria sampling, and long-term monitoring of water-quality, hydrologic and weather-related field parameters. Further details can be found in DEP’s Guidance for Surface Water Identification Protocol (383-3500-106) and Public Water Supply Module 3A – Groundwater Sources (3900-PM-BSDW0254D).