526 STORMWATER MANAGEMENT: RELIEF FROM EXTRAORDINARILY DIFFICULT SITE CONDITIONS

526.1 The applicant may apply for relief from extraordinarily difficult site conditions if it is technically infeasible or environmentally harmful:

1. (a) For a site to comply with the minimum on-site retention requirement (fifty percent (50%) of Stormwater Retention Volume (SWRv));
2. (b) For an Anacostia Waterfront Development Zone (AWDZ) site to comply with any portion of its WQTv or SWRv on-site, except that AWDZ sites may also apply based on the limited appropriateness of on-site stormwater management ; or
3. (c) For a site to comply with the minimum on-site retention or treatment requirements for SDAs (fifty percent (50%) retention or treatment of the SWRv from each SDA and fifty percent (50%) retention or treatment of the SWRv from the entire vehicular access area).

526.2 The Department shall not provide relief unless the applicant proves that on-site compliance is technically infeasible or environmentally harmful, except that, for an AWDZ site, the Department may also consider the appropriateness of on-site compliance in terms of impact on surrounding landowners or overall benefit to District waterbodies.

526.3 In order to support its case for relief, the applicant shall provide the following information demonstrating technical infeasibility or environmental harm:

1. (a) Detailed explanation of each opportunity for on-site installation of a Best Management Practice (BMP) that was considered and rejected, and the reasons for each rejection;
2. (b) Evidence of site conditions limiting each opportunity for a BMP, including, as applicable:
3. (1) Data on soil and groundwater contamination;
4. (2) Data from percolation testing;
5. (3) Documentation of the presence of utilities requiring impermeable protection or a setback;
6. (4) Evidence of the applicability of a statute, regulation, court order, pre-existing covenant, or other restriction having the force of law;

(5) Evidence that the installation of a retention BMP would conflict with the terms of a non-expired approval, applied for prior to the end of Transition Period Two A for a major land-disturbing activity or before the end of Transition Period Two B for a major substantial improvement activity, of a:

(A) Concept review by the Historic Preservation Review Board;

(B) Concept review by the Commission on Fine Arts;

(C) Preliminary or final design submission by the National Capital Planning Commission;

(D) Variance or special exception from the Board of Zoning Adjustment; or

(E) Large Tract Review by the District Office of Planning;

(6) For a utility, evidence that a property owner on or under whose land the utility is conducting work objects to the installation of a BMP;

(7) For a major substantial improvement activity, evidence that the structure cannot accommodate a BMP without significant alteration, because of a lack of available interior or exterior space or limited load-bearing capacity; and

(8) For single- and two-family affordable housing, evidence of:

(A) The usability of space to achieve the proposed project purpose;

(B) Lack of the minimum CDA required for a BMP to be effective;

(C) The difficulty of conducting BMP maintenance;

(c) For single- and two-family affordable housing:

(1) Evidence of the sensitivity of receiving waterbody to stormwater runoff; and

(2) Evidence of the likelihood of runoff from the site to cause to erosion of land, transport of sediment, nuisance flooding.

526.4 An applicant for relief shall submit to the Department's submittal database:- (a) A complete application; and

- (b) Proof of payment of the applicable fee.526.5 The Department shall not consider an incomplete application for relief; except that if an application is substantially complete, the Department may begin consideration.526.6 In determining whether to grant relief, the Department may consider:- (a) The applicant's submittal;

- (b) Other site-related information;

- (c) An alternative design;

- (d) The Department's Stormwater Management Guidebook;

- (e) Another BMP that complies with the requirements of this chapter; and

- (f) Relevant scientific and technical literature, reports, guidance, and standards.526.7 After considering whether an application meets the requirements of this section, the Department may:- (a) Require additional information;

- (b) Grant relief;

- (c) Grant relief, with conditions;

- (d) Deny relief; or

- (e) Deny relief in part.526.8 No relief shall be granted unless, for the volume of relief granted, the Stormwater Management Plan (SWMP) for the project provides for:- (a) Use of off-site retention, with the Off-Site Retention Volume documented on the approved SWMP; and

(b) If the relief is from a minimum on-site retention requirement, treatment to remove eighty percent (80%) of total suspended solids.

SOURCE: Final Rulemaking published at 35 DCR 21 (January 1, 1988); as amended by Final Rulemaking published at 60 DCR 10640 (July 19, 2013); as amended by Final Rulemaking published at 67 DCR 818 (January 31, 2020).