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Bulletin 1-20 Stormwater 1 CITY OF ATLANTIC BEACH 800 SEMINOLE ROAD ATLANTIC BEACH, FL 32233 (904) 247-5800 BULLETIN 1-20 To: All Permit Applicants. From: Dan Arlington, CBO City Building Official Date: April 13, 2020 Re: STORMWATER STORAGE AREAS NEAR RESIDENTIAL FOUNDATIONS. Per COAB LDR, Section 24-68, a certain amount of storm water must be stored on site for all development, including residential properties. Per Florida Building Code-Residential (FBC-R), 401.3, Drainage. Lots shall be graded to drain surface water away from foundation walls. The grade shall fall a minimum of 6 inches in the first 10 feet. To ensure that the intent of all codes and regulations are satisfied, the following guidelines are provided for the approved locations of Stormwater Storage Areas within 10 feet of residential foundations. 1) Where lot lines, walls, slopes, or other physical barriers prohibit 6 inches of fall within 10 feet of a foundation, drains or swales shall be constructed to ensure drainage away from the structure. Alternatively, stormwater storage areas in some locations less than 10 feet from foundations may be approved with additional testing, engineering, and soil compaction tests. 2) Where stormwater storage areas are located less than 10 feet from a foundation: a. A soils investigation must be provided. The number and location of the test borings must be specified by the Engineer Of Record (EOR) and be conducted by a licensed geotechnical company. b. The EOR must provide a statement that the structure is designed for the nearby stormwater storage areas, based on the proposed survey, showing the stormwater storage areas, and the required soils investigation. c. Soil compaction tests will be required in the bottom of the foundation, at not more than 10-foot intervals. 2 3) In Side Yards, the top of bank of any stormwater storage area must be a minimum of 10-feet from the minimum side setback line of the adjacent property. Either a or b, below, will apply. a) In zoning districts with a minimum 5-foot side setback, stormwater storage areas must be minimum 5 feet from the property line. b) In zoning districts with a minimum 7.5-foot side setback, stormwater storage areas must be minimum 2.5 feet from the property line. Drains and swales constructed as stormwater conveyance features can be approved in Side Yards. 4) The top of bank of any stormwater storage area must be a minimum of 2 feet from any street, sidewalk, walkway, or driveway, to protect pedestrians, bicyclists, and vehicles, per COAB LDR, Section 19-5(b). 5) In Front and Rear Yards, the top of bank of any stormwater storage area must be a minimum of 2 feet from any property line to protect the stability of neighboring properties. 6) Except as required to meet drainage or stormwater requirements, elevations and topography shall not be altered, per COAB LDR, Section 24-68, and changes to grade shall not alter natural drainage, per COAB LDR, Section 24-82(k). 7) Where any change of elevation or topography is proposed, to meet stormwater drainage requirements, including fill, berms, and retaining walls, topographic surveys of all adjacent properties must be provided to ensure that natural drainage patterns are not altered. 8) The design of underground stormwater storage systems must be site-specific and approved by Public Works and the City Engineer. DEFINITIONS: Yard, front means the required yard extending across the full width of the lot, extending from the front lot line to the front building setback line as established by the zoning district designation. Yard, rear means a required yard extending across the full width of the lot, extending between the rear lot line and the rear building setback line as established by th e zoning district designation. Yard, side means a required yard extending between a side lot line and the side building setback line as established by the zoning district designation. Development on infill lots in our established neighborhoods involves many issues and a number of codes and regulations to ensure the welfare of the new and existing property owners. Some of those issues are stormwater drainage and storage, and flooding, addressed in this Bulletin. All of the above requirements must be met for new developments. Where any conflict exists, between the requirements, the most restrictive shall govern. Revised: 6/15/2021