6206 RISK-BASED CORRECTIVE ACTION (RBCA) PROCESS

6206.1 Risk-based decision making and development of a risk-based corrective action (RBCA) plan shall be conducted in accordance with this section and the Department's RBCA technical guidance, which is available on the Department's website at https://doee.dc.gov/page/lust-forms-guidance-and-public-documents.

6206.2 Before initiating a risk-based decision making process to develop a RBCA plan for releases, a responsible party shall:

1. (a) Prevent further release from the UST by removing all products from the UST, or if approved by the Department, removing a lesser amount and performing any necessary repairs to the UST;
2. (b) Remove measurable free product to the maximum extent practicable;
3. (c) Remove impacted source material to the maximum extent practicable; and
4. (d) Select a qualified risk assessor who has successfully completed a risk-based corrective action training, such as training provided by the Interstate Technology & Regulatory Council, ASTM International, the U.S. Environmental Protection Agency, a state government, or a third party approved by the Department in accordance with § 5500.5.

6206.3 A responsible party using RBCA shall:

1. (a) Perform an initial site assessment, including identification of potential exposure pathways, take response action(s) as set forth in § 6203, and submit a work plan;
2. (b) Complete site classification as described in the Department's RBCA technical guidance, available on the Department's website at https://doee.dc.gov/page/lust-forms-guidance-and-public-documents, including a qualitative evaluation of the site based on known or readily available information to identify the need for interim remedial actions and further information gathering;
3. (c) Complete the comprehensive site assessment pursuant to § 6205 and the Tier 1 site assessment as described in the Department's RBCA technical guidance, which is available on the Department's website at https://doee.dc.gov/page/lust-forms-guidance-and-public-documents;
4. (d) Compare the concentrations of chemicals of concern with Tier 1 risk-based screening levels, which are specified in the Department's RBCA

technical guidance, available on the Department's website at https://doee.dc.gov/page/lust-forms-guidance-and-public-documents;

(e) If the concentrations exceed Tier 1 risk-based screening levels, develop and implement a corrective action plan to achieve Tier 1 levels or proceed to perform Tier 2A or 2B site-specific evaluation as described in the Department's RBCA technical guidance, which is available on the Department's website at https://doee.dc.gov/page/lust-forms-guidance-and-public-documents;

(f) If necessary for development of Tier 2 site-specific target levels, collect additional site-specific information and perform fate and transport analysis, including modeling, to determine points of demonstration;

(g) Develop and implement a corrective action plan to achieve the site-specific target levels or monitor for compliance; and

(h) When computer models are used in support of a case closure or no further action determination, provide a statement that the responsible party's staff or third-party contractor has been trained in the use of the District's RBCA software, which is available by contacting the RAM Group of Gannett Fleming, Inc. by e-mail to admin@ramgp.com, or other software, systems, or computer-based programs approved by the Department in accordance with § 5500.4.

6206.4 For RBCA in the District:

(a) The chemicals of concern shall include the petroleum products or by-products listed in Table 1 and any others deemed appropriate by the Department:

Table 1 – Chemicals of Concern

Benzene
Toluene
Ethylbenzene
Xylenes (total)
Ethylene dibromide (EDB)
Ethylene dichloride (EDC (1,2-DCA))
Methyl-tert-butyl-ether (MTBE)
Tertiary butyl alcohol (TBA)
Ethanol
Acenaphthene
Anthracene

Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chrysene
Fluoranthene
Fluorene
Naphthalene
Phenanthrene
Pyrene NC
TPH GRO
>C6-C8 Aliphatics
>C8-C10 Aliphatics
>C8-C10 Aromatics
TPH DRO
>C10-C12 Aliphatics
>C12-C16 Aliphatics
>C16-C21 Aliphatics
>C10-C12 Aromatics
>C12-C16 Aromatics
>C16-C21 Aromatics
TPH ORO
>C21-C35 Aliphatics
>C21-C35 Aromatics

(b) The point(s) of demonstration shall be:

(1) For Tier 1 assessment:

(A) The point of release or the source area;

(B) Groundwater affected by the contaminant plume, including any areas of the plume that are outside of the property boundary in accordance with the Department's RBCA technical guidance; and

(C) Soil throughout the area of the soil contaminated by the release and within the property boundary.

(2) For Tier 2 assessments, the point between the source and the potential point of exposure as approved by the Department.

(c) The maximum tolerable human health risk for carcinogens shall be a one in one million (1x10⁻⁶) excess cancer risk level (the estimated incremental increase in cancer risk over a lifetime). For non-carcinogenic health effects, the hazard quotient and hazard index shall be no greater than one (1).

(d) The Tier 0 standards and the Tier 1 standards shall be the standards in §§ 6208 and 6209, respectively.

(e) The exposure routes shall include ingestion of groundwater or soil, dermal contact with surface water or soil, ground water protection, and inhalation of volatiles.

(f) For each exposure pathway, the points of exposure shall include groundwater, surface water, and soil and transport media shall include leaching to groundwater and soil vapor migration into buildings.

6206.5 If levels of chemicals of concern exceed the Tier 1 standards set forth in § 6209, the responsible party shall:

(a) Submit a corrective action plan pursuant to § 6207 to achieve the Tier 1 levels; or

(b) Conduct a Tier 2 site-specific evaluation following the procedures and protocols for Tier 2 evaluations contained in the Department's RBCA technical guidance, which is available on the Department's website at https://doee.dc.gov/page/lust-forms-guidance-and-public-documents.

6206.6 After completion of the RBCA process, the responsible party may apply for a case closure or no further action letter pursuant to the requirements of § 6210.

6206.7 For purposes of this section, the phrase "risk assessor" means an individual who evaluates the qualitative or quantitative risk posed to human health and the environment by the actual or potential presence or release of hazardous substances, pollutants, or contaminants.

SOURCE: Final Rulemaking published at 40 DCR 7835 (November 12, 1993); as amended by Final Rulemaking published at 46 DCR 7699 (October 1, 1999); as amended by Final Rulemaking published at 67 DCR 1778 (February 21, 2020).