Douglas County Drainage, Erosion, and Sediment Control (DESC) is a program integrated into Grading, Erosion, and Sediment Control (GESC) that provides compliance with environmental and construction regulations and activities. A Drainage, Erosion, and Sediment Control permit will provide compliance with all Federal, State, and local environmental regulations, ensure adequate drainage, and will implement effective Best Management Practices (BMPs) for erosion and sediment control. EVstudio has worked on numerous projects in Douglas County and is very familiar with Drainage, Erosion, and Sediment Control plan preparation and requirements. The information included in this article will provide a detailed understanding and requirements necessary to obtain a Drainage, Erosion, and Sediment Control permit for single-family detached residential units in Douglas County. A DESC permit is required for all projects that fall within the following criteria:
- New construction, land disturbance and/or lot grading associated with single-family detached residential units.
- Reconstruction and additions to single-family detached residential units.
- Construction of, addition to, or land disturbance and/or lot grading associated with non-habitable structures that require a Building Permit. (Barns, Detached Garages, Etc.)
- Swimming Pool Construction.
A Drainage, Erosion, and Sediment Control permit is not required for projects that fall within the following criteria:
- Construction of, addition to, or land disturbance and/or lot grading associated with non-habitable structures that do not require a Building Permit.
- Deck construction.
- Patio covers construction.
- Stand-alone retaining walls.
- Interior remodels.
- Vertical additions that do not change the existing foundation footprint.
Drainage, Erosion, and Sediment Control permit submittals shall include a DESC Permit Application, lot specific erosion and sediment control drawing, lot specific drainage plan, appropriate fees, and a complete Drainage, Erosion, and Sediment Control plan prepared by a professional Civil Engineer. Drainage, Erosion, and Sediment Control plans may require a licensed professional architect and/or land surveyor to be included in the preparation of the plans.
Drainage, Erosion, and Sediment Control plans shall conform to minimum standards required by Douglas County. Drainage, Erosion, and Sediment Control plans shall include standard Douglas County Best Management Practices for initial, interim, and final stages of construction as well as Douglas County Drainage, Erosion, and Sediment Control Plan standard Notes and Details. The Standard Notes and Details will increase Best Management Practices functionality and consistency, will save time, and will help define variables that will locate and size Best Management Practices. In addition to Best Management Practices and standard Notes and Details, the following eight components shall be incorporated into a Drainage, Erosion and Sediment Control Plan:
- Protect and preserve drainage-ways.
- Implement effective perimeter control.
- Protect steep slopes.
- Avoid clearing and grading of sensitive areas (wetlands, forested areas, wildlife habitats, etc.).
- Limit land disturbance.
- Provide access and construction controls.
- Protect inlets, storm sewers, and culverts.
- Stabilize exposed soils.
Drainage, Erosion, and Sediment Control plans for lot sizes of one acre or less shall be shown at a scale of one inch equals twenty feet on 8.5″ x 11″ or 8.5″ x 14″ paper and lot sizes greater than one acre shall be shown at a scale of one inch equals twenty feet on 11″ x 17″ or 24″ x 36″ paper. If the lot does not fit at a scale of one inch equals twenty feet, the disturbed areas shall be shown at one inch equals twenty feet with the remainder of the lot being shown at a scale that will allow it to fit on the page. Plans shall include the following information:
- Basic property information including street address, subdivision, filing, lot and block (Section, Township and Range, if unplatted).
- Limits of construction.
- North arrow.
- Property lines, easements, and setbacks.
- 100 Year floodplain limits if there is a floodplain on the lot.
- Spot elevation and drainage flow arrows with with minimum following elements:
- Drainage swales with spot elevations to the nearest tenth of a foot, drainage arrows to the nearest 1% labeled at 25 foot intervals.
- Spot elevations at each foundation corner, foundation elevation changes, driveway and garage entrance, and point of driveway discharge.
- Drainage arrows and slopes labeled at each foundation corner and labeled at 20 foot intervals along the foundation, and foundation elevation changes.
- Locations where existing storm water runoff enters the lot and discharges from the lot to any adjacent rights of ways, properties, or easements.
- Location, map symbol, and call-outs for all Best Management Practices with appropriate time of installation labeling.
- All improvements.
- All drainage information (Swales, flow arrows, etc.).
- Designer’s firm name and address.
- Designers signature block.
- Signature block shall include the following note: THE DRAINAGE, EROSION AND SEDIMENT CONTROL DRAWING INCLUDED HEREIN HAS BEEN PREPARED UNDER MY DIRECT SUPERVISION IN ACCORDANCE WITH THE REQUIREMENTS OF THE GRADING EROSION AND SEDIMENT CONTROL (GESC) CRITERIA MANUAL OF DOUGLAS COUNTY, AS AMENDED.
- Douglas County Drainage, Erosion, and Sediment Control Acceptance Block.
The drainage plan shall include detailed information regarding final grading and disturbed areas. The drainage plan shall conform to the following requirements:
- Slope Requirements – A 10% minimum and 33% maximum slope in the first ten feet away from foundation walls and a minimum 2% in all other disturbed areas.
- Drainage Swales – Swales shall have adequate depth, width, and slope to coney water off the lot.
- Retaining Walls – May be required to control grades, shall not encroach onto adjacent lots, and shall not be taller than four feet. Retaining walls greater than four feet shall require a Building Permit and shall be designed by a Professional Engineer.
- Driveways – Shall have a minimum of 2% away from the foundation.
- Downspouts and Sump Pumps – Shall discharge a minimum of four feet away from foundation walls.
Upon completion of the Drainage, Erosion, and Sediment Control plans, any appropriate documents (Application, appropriate fees, etc.) shall be submitted to the Douglas County Building Division for review. The Douglas County Building Division shall review the Drainage, Erosion, and Sediment Control plans and will notify the designer of any necessary modifications. The submittal and review process shall be repeated until the Drainage, Erosion, and Sediment Control plans are accepted. Upon acceptance of the Drainage, Erosion, and Sediment Control plans, field work can begin starting with a pre-construction meeting. EVstudio verifies that all requirements for DESC plans are met so that the Drainage, Erosion, and Sediment Control submittal process is as quick and smooth as possible.