517.1 If a major substantial improvement activity demonstrates that it is not part of a common plan of development with a major land-disturbing activity, then it is exempt from § 520 (Stormwater Management: Performance Requirements For Major Land-Disturbing Activity).

517.2 A land-disturbing or substantial improvement activity shall be exempt from the requirements of §§ 520 (Stormwater Management: Performance Requirements For Major Land-Disturbing Activity), 522 (Stormwater Management: Performance Requirements For Major Substantial Improvement Activity), and 529 (Stormwater Management: Covenants and Easements) if the Department determines that the activity is conducted solely to install a best management practice or land cover that retains stormwater for one or more of the following purposes:

(a) To generate SRCs;

(b) To earn a stormwater fee discount under the provisions of this chapter;

(c) To voluntarily reduce stormwater runoff in a manner that would be eligible to either generate SRCs or a stormwater fee discount, even if the person conducting the activity does not intend to apply to either program;

(d) To provide for off-site retention through in-lieu fee payments;

(e) To comply with a Watershed Implementation Plan established under a Total Maximum Daily Load for the Chesapeake Bay; or

(f) To reduce Combined Sewer Overflows (CSOs) in compliance with a court-approved consent decree, including court-approved modifications, for reducing CSOs in the District, or in compliance with a National Pollutant Discharge Elimination System permit.

517.3 A land-disturbing activity that consists solely of cutting a trench for utility work and related replacement of sidewalks and ramps is exempt from the stormwater management requirements of this chapter if it does not involve the reconstruction of a roadway from curb to curb or curb to centerline of roadway.

517.4 Land disturbance conducted solely to respond to an emergency need to protect life, limb, or property or conduct emergency repairs shall be exempt from the requirement to comply with the stormwater management provisions of this chapter, §§ 516-34.

517.5 For the purposes of calculating the cost of a major substantial improvement to a building or structure, an applicant may exclude the cost of replacing manufacturing and industrial equipment, including pumps, valve chambers, and wastewater treatment facilities, but may not exclude the cost of replacing boilers, furnaces, and other equipment that is part of the heating and cooling system or other infrastructure commonly found in a building or structure.

517.6 A land-disturbing activity in the existing PROW is exempt from the requirements in § 520 (Performance Requirements for Major Land-Disturbing Activity) for maintaining post-development peak discharge rates.

517.7 The portion of a land-disturbing activity that consists of the installation or replacement of athletic playing fields, permeable athletic tracks, or permeable playground surfaces shall be exempt from the stormwater management requirements of this chapter, provided that:

(a) The land-disturbing activity achieves the post-development peak discharge performance requirements for Major Land-Disturbing Activities, as documented on:

(1) A Soil Erosion and Sediment Control Plan approved by the Department that shows the project achieves the drainage layer and orifice sizing requirements of the Department's Stormwater Management Guidebook; or

(2) A Stormwater Management Plan approved by the Department;

(b) The pre-project land cover is compacted cover or impervious cover;

(c) The athletic playing field, permeable athletic track, or permeable playground surface is located at a school or public park and is made available for use by the general public; and

(d) If the athletic playing field, permeable athletic track, or permeable playground surface drains to a Best Management Practice (BMP), any gallon retained by the BMP shall only be eligible for SRC certification if the gallon is retained in excess of the stormwater retention and treatment performance requirements of this chapter for the area that is otherwise exempt pursuant to this subsection.

SOURCE: Final Rulemaking published at 35 DCR 21 (January 1, 1988); as amended by Final Rulemaking Water and Sanitation

published at 60 DCR 10640 (July 19, 2013); as amended by Final Rulemaking published at 67 DCR 818 (January 31, 2020).