519

STORMWATER MANAGEMENT: PLAN

519.1

A Department-approved stormwater management plan (SWMP) shall:

1. (a) Govern all construction for which stormwater management is required;
2. (b) Govern all applicable maintenance activities; and
3. (c) Demonstrate compliance with this chapter.

519.2

A submitted SWMP and supporting documentation shall contain information sufficient for the Department to determine whether the SWMP complies with this chapter including:

1. (a) Existing site conditions, including the identification and location of each existing Best Management Practice (BMP) and whether it will remain on the site and in use or will be removed;
2. (b) Proposed site design;
3. (c) Each land use proposed for the site;
4. (d) Identification and location of each proposed BMP, including geographic coordinates;
5. (e) Design and performance of each BMP for stormwater retention, detention, and treatment;
6. (f) Conveyance capacity of stormwater infrastructure;
7. (g) Environmental characteristics of the site;
8. (h) Pre- and post-development hydrologic computations, including:
9. (1) Calculation of required stormwater management volume for:
   1. (A) The entire site; and
   2. (B) Each individual drainage area; and
10. (2) On-site and off-site retention volumes;
11. (i) Maintenance plan and schedule for each proposed BMP;
12. (j) Monitoring plan for each BMP that captures stormwater for use;

(k) For each proposed BMP not included in the Department's Stormwater Management Guidebook (SWMG):

(1) Separate identification and description; and

(2) Documentation of performance and effectiveness;

(l) Construction sequence for:

(1) Each BMP; and

(2) The related development or improvement project, if any.

(m) A list of the construction and waste material to be stored on site and a description of the material and each pollution control measure that will be implemented to minimize exposure to stormwater discharge, including:

(1) Each storage practice;

(2) A spill prevention response;

(3) The United States Environmental Protection Agency (EPA) identification number, or copy of application to EPA for identification number, for each hazardous waste that will be stored on site; and

(4) Proof of payment of each applicable fee.

519.3 The retention capacity of each BMP in a SWMP shall be calculated using the applicable equations for calculating retention value in Chapter three (3) of the Department's Stormwater Management Guidebook.

519.4 The pollutant removal efficiency of each BMP in a SWMP shall be calculated using the applicable equation in Chapter three (3) of the Department's SWMG.

519.5 The Department may require for each area that a project proposes for use to meet the requirements of this chapter, including a contiguous area or an area with a shared BMP:

(a) Information listed in this section; or

(b) A SWMP.

519.6 A submitted SWMP shall use:

(a) A standard drawing size of twenty-four inches by thirty-six inches (24 in. x 36 in);

(b) One (1) of the following horizontal scales of profile, unless otherwise approved:

(1) One inch equals ten feet (1 in. = 10 ft.);

(2) One inch equals twenty feet (1 in. = 20 ft.);

(3) One inch equals thirty feet (1 in. = 30 ft.);

(4) One inch equals forty feet (1 in. = 40 ft.);

(5) One inch equals fifty feet (1 in. = 50 ft.); or

(6) One inch equals eighty feet (1 in. = 80 ft.);

(c) One (1) of the following vertical scales of profile, unless otherwise approved:

(1) One inch equals two feet (1 in. = 2 ft.);

(2) One inch equals four feet (1 in. = 4 ft.);

(3) One inch equals five feet (1 in. = 5 ft.); or

(4) One inch equals ten feet (1 in = 10 ft.); and

(d) Drafting media that yield first or second generation reproducible drawings with a minimum letter size of No. 4 (1/8 inch).

519.7 A SWMP shall not be approved without the signature and seal of the Director or the Director's designee on the plan.

519.8 For each as-built SWMP that an applicant submits to the Department, an applicant shall provide that a professional engineer licensed in the District of Columbia, certifies with seal and signature that:

(a) The design, and installation for an as-built plan:

(1) Conforms to engineering principles applicable to stormwater management; and

(2) Complies with the requirements of this chapter; and

(b) A set of instructions for operation and maintenance of each BMP has been provided to the applicant.

519.9 A SWMP for a project shall be consistent with each other project submittal, including:

(a) An erosion and sediment control plan; and

(b) A floodplain management plan.

519.10 The approved SWMP for a major regulated project shall be available on site for Department review for the entire period of construction during ordinary business hours.

SOURCE: Final Rulemaking published at 60 DCR 10640 (July 19, 2013).