HIGHLIGHTS:

  • The U.S. Environmental Protection Agency (EPA) published a Notice of Intent to Reissue the District of Columbia's municipal separate storm sewer system (MS4) permit.
  • EPA's proposed permit retains many of the provisions of the District's 2011 permit, but also proposes a number of new enforceable milestones and adaptive management benchmarks.
  • The District's development community is encouraged to comment on EPA's proposed permit during the 45-day public comment period that will end on Jan. 2, 2017.

The U.S. Environmental Protection Agency (EPA) published on Nov. 17, 2016, a Notice of Intent to Reissue the District of Columbia's municipal separate storm sewer system (MS4) permit. The notice triggers a 45-day public comment period that will end on Jan. 2, 2017.

EPA acknowledges that the District has a solid foundation of green infrastructure, an innovative Stormwater Retention Credit (SRC) system and some of the most effective on-site stormwater retention regulations in the country. Nevertheless, EPA proposes to add numerous enforceable stormwater milestones and adaptive management benchmarks to the District's MS4 permit, many of which will make new development efforts in the District more complex and costly.

Key Components

EPA's proposed MS4 permit would require the District to do the following:

  • perform a cost-benefit analysis of increasing the on-site stormwater retention standard from 1.2 inches to 2 inches
  • manage 1,038 acres on which stormwater control measures are implemented and ensure that 350,000 square feet of green roofs are installed by 2021
  • evaluate options to increase the District's Stormwater Fee to fund projects to improve water quality
  • optimize stormwater management procedures at small projects over the next two years in order to eliminate the stormwater management exemption for small projects

Background

EPA's proposed MS4 permit will replace the District's 2011 permit, which was modified in 2012 and was scheduled to expire on Oct. 7, 2016. The proposed permit retains many of the provisions of the 2011 permit, but also proposes a number of new enforceable milestones and adaptive management benchmarks. The new permit requirements are discussed below.

New Discharge Limits

Section 1.5 of the proposed permit sets new discharge limits for the District's MS4 system. The permit would require the District to remove 103,188 pounds of trash from the Anacostia River Basin annually. For additional pollutants of concern, the permit proposes to use the number of acres that are subject to stormwater management controls as a compliance metric. By 2021, the permit would require the District to manage 1,038 acres, a 250 percent increase from the 2011 permit. Of these 1,038 acres, at least 46 must consist of retrofitted Public Right-of-Way (PROW) areas, a 33 percent increase from the 2011 permit.

Click here to view the table.

Stormwater Management Program Implementation

EPA's proposed MS4 permit includes the following new requirements for implementing the District's stormwater control measures:

  • Limit SRCs for Older Development Projects: Stormwater retention projects installed before July 2013 will only be eligible to generate SRCs if the project submits an application within six months after the effective date of the reissued MS4 permit.
  • Establish SRC Purchase Agreement Program: The District shall commit $12.75 million to establish a SRC purchase agreement program and to provide technical support to identify sites with potential to generate SRCs. All SRCs purchased by the District would be retired to achieve additional benefit to District water bodies.
  • Increase Green Roof Construction: The District shall ensure that at least 350,000 square feet of new green roofs are installed by 2021.
  • Increase Tree Canopy: The District shall achieve a net annual tree planting rate of 8,000 plantings in pursuit of an urban tree canopy coverage rate of 40 percent by 2032.
  • Implement Stormwater Pollution Prevention Plans (SWPPPs) at District Facilities: The District shall ensure that SWPPPs are implemented at all of its facilities and properties where industrial activities occur.
  • Implement Storm Drain Outfall Operation and Maintenance: The District must annually repair 10 percent of damaged storm drain outfalls or substitute outfall repairs with more beneficial stream restoration projects.
  • Implement Street Sweeping Program: The District shall street sweep 44,000 miles of road annually.

Stormwater Management Program Planning

The District's 2011 permit required the development of a Consolidated Total Maximum Daily Load (TMDL) Implementation Plan as a long-term road map for addressing water quality impairments related to the MS4. The District's TMDL Implementation Plan, released in August 2016, does not anticipate achieving full compliance with all wasteload allocations (WLAs) until 2154. Accordingly, EPA proposes to insert the following requirements into the District's MS4 permit in an effort to bring about swifter improvements in water quality:

  • Create Schedule for Updating TMDLs: During the first year of the permit, the District shall create a schedule for revising TMDLs that are based on old or limited data.
  • Evaluate Stormwater Fee Options: The District shall evaluate options over the next three years to increase the Stormwater Fee to fund projects to achieve WLAs.
  • Analyze Increase to On-Site Stormwater Retention Standard: The District shall conduct a cost-benefit analysis over the next three years on the effect of increasing the on-site stormwater retention standard from 1.2 inches to 2 inches or applying a stricter standard in target watersheds.
  • Study Sources of E. coli in MS4: The sources of E. coli in the District's MS4 are largely unknown. The District shall study the sources of E. coli and use that information to develop more aggressive milestones for achieving the E. coli WLA.
  • Minimize Legacy Pollutants: The District shall confirm that legacy pollutants such as DDT and PCBs are no longer being discharged through the MS4 and develop a plan to address any legacy pollutants that still adversely impact water quality, including potential sediment remediation measures.
  • Eliminate Stormwater Exemptions for Small Projects: The District shall optimize stormwater management procedures at small projects over the next two years to eliminate the exemption of small projects from stormwater management requirements.
  • Optimize Stormwater Design for PROWs: To enable the District to have 46 acres of retrofitted PROWs subject to stormwater management controls by 2021, the District shall develop optimal stormwater designs for categories of PROWs over the next four years.
  • Evaluate Pollutant Reductions From Catch Basin Cleaning: The District shall develop a method for calculating pollutant reductions from routine catch basin cleaning.
  • Incorporate Water Quality Elements Into Snow Response Plan: The District shall evaluate its use of anti-icers, chemical deicers, salt and sand, and make efforts to minimize the impact of these substances on water quality.
  • Incorporate Flood and Climate Management Assessments Into Stormwater Management: The District shall review all floodplain development to ensure that it is reasonably protected from flooding, does not reduce flood storage and does not impact water quality. The District shall also use estimates of future climate conditions when evaluating the need for revised stormwater management standards.

Water Quality Assessment

The 2011 MS4 permit required the District to develop a new water quality assessment strategy. EPA has reviewed and approved the District's Revised Monitoring Program and incorporated it into the draft MS4 permit. Accordingly, the permit requires the District to 1) conduct wet weather monitoring of key pollutants of concern, 2) assess the MS4's receiving waters via evaluations of water quality, habitat, macroinvertebrates and geomorphology, and 3) conduct trash monitoring in the Rock Creek, Anacostia River and Potomac River watersheds.

Reporting Requirements

The proposed permit requires the District to create annual reports that track its progress toward meeting the permit's numeric milestones and to publish those annual reports, as well as other stormwater management program documents, on the District's website.

It is important that the development community weigh in on these proposed changes by Jan. 2, 2017. Contact the authors for assistance in making your views known to EPA.