250 R.I. Code R. 250-RICR-150-05-3.11

Current through November 7, 2024

Section 250-RICR-150-05-3.11 - Groundwater Quality Standards and Preventive Action Limits

A. Class GAA and class GA Groundwater Quality Standards: Class GAA and class GA groundwater are suitable for drinking water use without treatment, and therefore, both classes are subject to the same groundwater quality standards below in §§ 3.11(A)(1) through (4) of this Part. Exceedances of the groundwater quality standards that are determined by the Director to be caused by naturally occurring conditions will not be considered a violation of the groundwater quality standards. In those areas where the groundwater is classified GAA or GA and the groundwater does not meet the groundwater quality standards, the groundwater classification remains GAA or GA with the goal to regain compliance with the groundwater quality standards.

1. Pollutants shall not be in groundwater classified GAA or GA, except within an approved pollutant discharge zone or residual zone (as provided for in §§ 3.12(D) and (E) of this Part respectively), in any concentration which will adversely affect the groundwater as a source of safe and potable drinking water or which will adversely affect other beneficial uses of the groundwater, to include but not be limited to recreational, agricultural and industrial uses and the preservation of fish and wildlife habitat through the maintenance of surface water quality.

2. The numerical groundwater quality standards for specific substances in class GAA and class GA shall be the federal maximum contaminant levels for drinking water established by the United States Environmental Protection Agency National Primary Drinking Water Regulations 40 C.F.R. §§ 141.60 through 141.66 and 141.80, incorporated above at § 3.6(B) of this Part. For a substance with no maximum contaminant level, the groundwater quality standard for class GAA and GA groundwater shall be determined by the Director on an interim basis in accordance with R.I. Gen. Laws § 46-13.1-4, and such standard shall be consistent with the contaminant level determined by the Rhode Island Department of Health pursuant to R.I. Gen. Laws § 46-13-10. The Department shall notify the public of such interim standard. The Department shall initiate rulemaking, pursuant to R.I. Gen. Laws § 42-35-2.7, to incorporate a standard for a substance with no maximum contaminant level into these regulations within six months of making the interim determination. The interim standard shall remain in effect until a final standard has been incorporated into these Rules. The Director has established the following GAA and GA groundwater quality standards for contaminants that do not have a maximum contaminant level established:

a. Methyl tertiary butyl ether (MTBE) -- 0.04 milligrams per liter;

b. Naphthalene -- 0.1 milligrams per liter;

c. [PFOS] + [PFOA] + [PFNA] + [PFDA] + [PFHxS] + [PFHpA] [GREATER THAN AND EQUALS TO] 20 nanograms per liter

Where,

PFOS = perfluorooctane sulfonate

PFOA = perfluorooctanoic acid

PFNA = perfluorononanoic acid

PFDA = perfluorodecanoic acid

PFHxS = perfluorohexane sulfonic acid

PFHpA = perfluoroheptanoic acid

3. Pollutants shall not be in groundwater classified GAA or GA that exceed levels which the Director has determined render the groundwater so impaired for taste, odor or color that a person cannot reasonably be expected to consume or otherwise use it.

4. Groundwater classified GAA and GA shall be of a quality which the Director determines does not violate or have any reasonable potential to cause a violation of surface water quality standards established by the Rhode Island Water Quality Regulations Part 1 of this Subchapter.

5. Groundwater classified GAA and GA shall not have non-aqueous phase liquids present in either a mobile or immobile state at or below the surface of the water table.

B. Class GAA and GA Preventive Action Limits: Class GAA and class GA groundwater are subject to the preventive action limits defined below:

1. The preventive action limits shall be set at 50% of the numerical groundwater quality standards established pursuant to § 3.11(A)(2) of this Part.

2. The preventive action limits shall be used in monitoring discharges to groundwater approved by the Director and monitoring groundwater that may be impacted by such discharges. Preventive action limits are not applicable in determining groundwater remediation objectives.

C. Class GB and GC Groundwater Quality Standards: Classification of groundwater as GB or GC does not convey the right to degrade groundwater quality. Limited degradation of groundwater quality may occur as a result of legally authorized activities related to siting, permitting and remediation where groundwater is classified GB or GC. In those areas where the groundwater is classified GB or GC and the groundwater does not meet the GB or GC groundwater quality standards, the groundwater classification remains GB or GC with the goal to regain compliance with the groundwater quality standards. Groundwater classified GB and GC shall be of a quality which the Director determines does not:

1. Threaten public health or the environment;

2. Violate or have a reasonable potential to cause a violation of surrounding groundwater quality standards;

3. Adversely impact or have a reasonable potential to adversely impact current or future uses of property, groundwater, or surface water;

4. Violate or have any reasonable potential to cause a violation of surface water quality standards established by the Rhode Island Water Quality Regulations, Part 1 of this Subchapter; and

5. Have non-aqueous phase liquids present in either a mobile or immobile state at or below the surface of the water table.

D. Proposed activities where the groundwater is classified GB in accordance with §§ 3.9(A)(3)(b) through (d) of this Part that would otherwise be prohibited in the surrounding areas where the groundwater is classified GA or GAA may at the Director's discretion be subject to the Department's review to ensure that the surrounding groundwater quality is protected.

E. In determining compliance with the groundwater quality standards for class GB and class GC at a facility, the Director may consider the factors below, in addition to other relevant information, provided by the facility owner or operator:

1. Surrounding groundwater quality;

2. Groundwater classification surrounding the facility;

3. Surface water classification within the facility boundaries and surrounding the facility;

4. Current and proposed future uses of groundwater and surface water at or within the facility boundaries;

5. Current and proposed future uses of the facility;

6. Uses of surrounding property, groundwater and surface water;

7. Hydrogeologic characteristics of the facility and surrounding the facility, including, but not limited to, groundwater flow direction, hydraulic gradient, type of subsurface materials, and depth to bedrock;

8. Actual and potential routes for human exposure and points of human exposure to the pollutant(s);

9. Man-made pathways for pollutant movement off-site, e.g., underground utility lines; and

10. Persistence and mobility of the pollutant(s) in the subsurface and the toxicity of the pollutant(s).

250 R.I. Code R. 250-RICR-150-05-3.11

Adopted effective 1/9/2019
Amended effective 12/28/2023