The purpose and intent of drainage plans at time of building permit application is to manage stormwater runoff and establish site grading and water management standards for single-family, two-family attached, and duplex residential lots to prevent detrimental impacts on site or to adjacent properties and/or water-bodies. A properly submitted drainage plan is key to the site plan review process as part of a building permit.
A storm-water drainage plan is required at time of building permit for all new residential structures, additions, pools, accessory structures, and decks on single-family, two-family attached, and duplex residential lots with the following exceptions:
Open wooden decks, non-roofed, 500 square feet or less.
Structural additions 500 square feet or less, and more than ten feet from property line.
Accessory structures 200 square feet or less, and more than ten feet from property line.
Any other impervious area 200 square feet or less. For the purposes of this section, the term impervious area shall include roofed buildings, concrete and asphalt pads, pool deck (e.g. spraycrete), pavers with limerock base and swimming pools.
Replacement mobile homes.
A stormwater drainage plan is required for all new residential structures, additions, pools, accessory structures, and decks as identified above. The drainage plan must be prepared by a professional engineer, architect or land surveyor as part of an application for building permit for a single family, two family attached and duplex dwelling.
Drainage plan requirements may be modified if an acceptable alternate plan is provided. Drainage plan requirements for permits within developments that have received local development order approval may be modified based on the lot grading drainage plan and overall stormwater management design.
Stormwater drainage plans shall include the following:
Show the method of erosion control, such as, but not limited to, silt fences, turbidity barriers, and filter fabric as outlined in the Florida Stormwater Sedimentation Control Inspector’s Manual or a similar quality guidance manual.
Gutters and downspouts are required where the roof overhang is less than 10' from the property line. The gutters and downspouts must be properly sized and direct stormwater away from adjacent properties and into swales or retention/detention areas. When the set back to the roof overhang is greater than 10', gutters and downspouts will be required when needed to prevent or mitigate increased drainage impacts onto adjacent properties.
Show the dimensions and details of all existing and proposed drainage solutions including but not limited to:
Swales and berms. Show location and elevation.
Gutters and downspouts.
Inlets. If inlets are proposed, provide details showing grate and pipe elevations.
Retaining walls. Retaining walls shall not be placed closer than one foot from the property line and per LDC Section 7-385 for waterbody setbacks. For height restrictions reference LDC Section 4-1467(b).
French drains. The stone in french drains shall provide a minimum void ratio of 40 percent.
Show all cross-sections of the development from the area of construction to the property line in all directions (north, south, east and west), matching the existing elevations.
Show the location and elevation of all existing and proposed drainage solutions mentioned in 4-2224(d)(1)i.3.
Graded slopes shall not be any steeper than 5:1, unless otherwise approved by the city during the drainage review process.
Existing and proposed elevations
A minimum of a 50 foot by 50 foot grid.
A minimum of five feet on to the adjacent property.
Existing elevation of crown of roadway.
Elevations to establish the transition to existing grades at adjacent property lines and/or any waterbody.
Sidewalks. Label and provide the dimensions, elevations, and cross-sections of all sidewalks, if applicable pursuant to LDC Section 4-870(2).
Pools. Show the location of overflow; a french drain may be required at this location.
Closed drainage may be required along the property frontage adjacent to all city owned rights-of-way pursuant to LDC Sections 3-302 and 3-303.
Drainage arrows clearly delineating the direction of flow.
All materials used for ground cover, such as, but not limited to, sod, mulch, rock, artificial turf grass, and shell.
During the review of the drainage plan, the city reserves the right to require water quantity calculations by a professional engineer for lots that exceed 30 inches above the grade of existing adjacent lots. Calculations must demonstrate the ability to accommodate the runoff from a 5-year 1-day storm.
Sites must be graded and maintained during construction to:
Prevent erosion of soil onto adjacent and abutting properties, street rights-of-way/easements, waterbodies or improved drainage conveyances;
Ensure erosion control devices are being maintained as outlined in the Florida Stormwater Sedimentation Control Inspector’s Manual or a similar quality guidance manual;
Control surface water runoff to ensure that no surface water in excess of the preconstruction discharge flows onto developed adjacent or abutting properties and waterbodies; and
Maintain the flow capacity and function of existing drainage conveyances on or abutting the site including adjacent street rights-of-way/easements or improved drainage conveyances.
An “as-built” of the constructed drainage plan prepared and certified by a professional engineer, architect or land surveyor may be required as part of the building permit approval. Staff will notify an Applicant at time of building permit review if a final site grading plan is required. Final site grading plans shall be submitted prior to final inspection, certificate of completion or certificate of occupancy of the structure. This “as-built” shall be reviewed to determine if the work completed is in substantial compliance with approved plan.
Items not in compliance with the approved drainage plan will be noted by the city and brought to the attention of the property owner or his representative for correction. Any revisions to an approved drainage plan must be submitted for review and approved prior to certificate of occupancy or certificate of completion.
The city reserves the right to inspect the site during construction and/or prior to issuance of a certificate of occupancy or certificate of completion to ensure consistency with the approved drainage plan pursuant to LDC Section 4-2224(d)1.
Final grading of a lot must:
Control and direct surface water runoff to ensure that surface water discharge is directed into an existing surface water management system or other offsite drainage conveyance; and
Preserve or relocate existing drainage conveyances necessary to maintain preconstruction flow capacity and function.
Final site grading plan features must be maintained in perpetuity by the property owner. A property owner may not alter or modify the lot grading in a manner that will prevent continued drainage of the site in accordance with the storm water drainage plan in effect at the time the certificate of occupancy or certificate of completion was issued.
No. The applicant shall apply for a Type 99 Limited Review Development Order if any fill is being added to a residential lot that is not accompanied with a building permit. Modifications that alter the drainage flow and which may cause flooding of other properties, public or private, are a violation and are hereby declared a public nuisance and are prohibited. Violations will be referred to the neighborhood services department. Corrective action requires submission of a drainage plan in accordance with this section that demonstrate no detrimental impacts on site or to adjacent properties and/or waterbodies.
If you are uncertain about a specific regulation, we encourage you to contact a member of engineering (239) 444-6150. We’ll be happy to assist you any way we can.
Sample Rendering of a Proper Drainage Plan Submittal
(written authorization received by design professional to post rendering)
Sample 1 Drainage Plan
Sample 2 Drainage Plan
Sample 3 Drainage Plan
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