The District of Columbia Department of Energy and Environment (DOEE) published a Notice of Proposed Rulemaking (Proposed Rule) to adopt a new Chapter 16 – Discharge of Groundwater to the Municipal Separate Stormwater Sewer System (MS4) – as an amendment to Title 21 of the District of Columbia Municipal Regulations (DCMR). The Proposed Rule, published in the D.C. Register on May 26, 2023, would develop a regulatory permitting system to authorize certain discharges into the District's MS4.
The Proposed Rule sets forth a process by which eligible applicants can obtain a permit (referred to as a Groundwater Discharge-to-MS4 Individual Permit) for uncontaminated discharges of groundwater made directly into the District's MS4. Uncontaminated discharges of groundwater include discharges that meet the District's Surface Water Quality Standards (SWQS). The Proposed Rule would not cover stormwater discharges, unless commingled with groundwater. Further, the Proposed Rule would apply only to properties or operations located within the District's MS4 area. The Proposed Rule would not apply to a) discharges that require a federal National Pollutant Discharge Elimination System (NPDES) Permit other than the Construction General Permit (CGP) or Multi-Sector General Permit (MSGP), b) discharges to the District's combined or sanitary sewer system or c) direct discharges to surface waters that do not flow through the MS4.
Process to Obtain a Permit
To obtain a Groundwater Discharge-to-MS4 Individual Permit for properties/operations discharging to the MS4 (other than one- or two-story residential homes), the Proposed Rule would require applicants to submit the following information to the DOEE:
- an application form provided by DOEE, which shall include a brief description of the site history, dewatering practices, proposed discharges, and a quality assurance and quality control project work plan, among other information
- an initial discharge characterization report, including Phase I Environmental Site Assessment (ESA), and in some instances, a Phase II ESA and/or data from water samples
- applicable application fees, which, for nonresidential sites, can range from $2,000 to $15,000
An applicant that samples its proposed discharges as part of the application would be required to collect the samples from a groundwater quality monitoring well, a storage tank or a discharge point to the sanitary sewer if the applicant currently holds a Temporary Discharge Authorization (TDA) from D.C. Water. If results of the initial characterization or sampling contain concentrations exceeding the District's SWQS, the applicant would also be required to submit a water treatment system plan.
Under the Proposed Rule, the applicant would be required to sample for hundreds of substances, for many months, using test methods that can be achieved by only a handful of labs throughout the United States. This is not considered reasonable by many developers and other industry stakeholders. Some have expressed that, if there are contaminants of concern on a site, the sampling should be targeted to those compounds and testing promptly eliminated for other substances, and the applicant should be allowed to use commonly available lab testing methods.
Any person who previously obtained a discharge authorization letter from DOEE for discharges into the MS4 would be required to obtain a new Groundwater Discharge-to-MS4 Individual Permit within 60 days of the effective date of the Proposed Rule. However, in applying for the permit, the applicant would be permitted to provide discharge monitoring reports collected pursuant to the discharge authorization letter in lieu of an initial characterization report. As with the initial characterization report, a water treatment system plan would be required if the monitoring reports reveal concentrations of contaminants exceeding the SWQS. Many in the industry think it would be more appropriate to grandfather in these prior approvals, and require the permittee to comply with the new rules upon the next permit renewal cycle.
DOEE proposes to have a public notice and comment on the proposed permit prior to issuing a Groundwater Discharge-to-MS4 permit. Once approved, the permit would contain individual permit limits for contaminants based on the District's SWQS, as well as monitoring and reporting requirements. All permittees would be required to monitor their discharges for certain parameters, including flow rate, oil and grease, pH, total suspended solids, volatile organic compounds and semi-volatile organic compounds. In addition, permitted sites with known contamination would be subject to monitoring requirements for the specific identified contaminants at the site.
In some instances, such as for dissolved iron, manganese, nickel and zinc, permit limits would be allowed to exceed the SWQS, if the permittee can demonstrate, through DOEE's Reasonable Potential Analysis (RPA), that there is no reasonable potential for the discharge to cause an exceedance of the SWQS in the receiving water. It is not clear why DOEE did not include other naturally occurring metals, such as arsenic (a common naturally occurring metal in soils in the District), within the list of substances for which a permittee can submit an RPA. All discharge monitoring results would be required to be reported to DOEE within 30 days after the sampling event. Permittees could request ceasing or modifying the monitoring of certain pollutants if they can demonstrate that monitoring is no longer necessary through several consecutive sampling results.
Takeaways and Next Steps
Permits issued for construction discharges into the MS4 would be valid for two years after approval, and could be renewed for additional two-year periods. Permits for nonconstruction discharges into the MS4 would be valid for five years, and could be renewed for additional five-year periods. The District would be permitted to institute civil or criminal action against any person who violates the regulations or permit requirements.
DOEE will host public meetings on the Proposed Rule on June 20-21, 2023. Additional information is available from the DOEE.
Comments on the Proposed Rule must be submitted to DOEE by July 25, 2023. Interested persons may also request a hearing on the Proposed Rule by submitting a request in writing by July 25, 2023. The authors can assist property owners and operators in the preparation and submission of comments.
