Town of Ocean View, DE Article I Site Grading Standards

§ 132-1 General design standards.

General design standards shall:

A. Provide protection for buildings from stormwater damage by directing stormwater runoff away from the building via land grading adjacent to the building.

B. Handle existing off-site runoff through the development by installing adequate conveyance systems to accommodate the design storms as specified herein.

C. Ensure that surface water flows that become concentrated occur in a conveyance system of adequate capacity as specified herein.

D. Collect concentrated on-site runoff and convey the runoff from the point of discharge into the common natural watercourse of the drainage area, or to such other point approved by the Town. Transport stormwater runoff for up to twenty-five-year frequency storms to the designated stormwater management facility by means of adequate conveyance systems.

E. Maintain or improve the flow characteristics for runoff leaving the site.

F. Seek to conform post-development grading to existing topography and protect designated resource areas on the site to the maximum practical extent.

§ 132-2 Specific design standards.

The ground on which structures are located shall be graded to carry stormwater runoff away from the buildings and dispose of it without causing water to pond, except in approved designated areas. Land grading shall comply with the following specific standards:

A. Minimum protective slopes around a dwelling. Grading of pervious areas for a minimum distance of eight feet away from any building shall slope perpendicularly away from the building toward areas designated to accept runoff. The minimum slope in this area shall be 16 feet horizontal to one foot vertical (16:1) (net differential in grade: 0.50 of a foot). Lesser slopes or shorter distances may be approved in specific cases where application of these requirements is not feasible and where an alternative method of foundation protection is provided to the satisfaction of the Town. If the sloped area is greater than eight feet in length, the slope may be reduced. However, the net differential in grade must be at least 0.5 of a foot and provide a slope of at least 2.00%.

B. Maximum protective slopes around a dwelling. In grading of pervious areas for a minimum of four feet from the foundation of any building, the slope shall not be steeper than four feet horizontal to one foot vertical (4:1). The maximum man-made slope at any place on a developed lot shall not be steeper than two feet horizontal to one foot vertical (2:1), and any man-made slope steeper than three feet horizontal to one foot vertical (3:1) shall be designed according to the applicable provisions of the Delaware Erosion and Sediment Control Handbook, to ensure slope stability and minimize maintenance requirements.

C. Driveways. The maximum grade slope shall be 8%. Driveways sloping toward buildings shall be graded to a low point located at least eight feet from the building with a minimum vertical elevation difference of 0.50 foot between the elevation at the building and the low point. The low point shall be graded to drain away from the building.

D. Fill slopes. The toe of slope on any fill steeper than four feet horizontal to one foot vertical (4:1) on any individually developed lot must be maintained at a minimum of two feet from the nearest property line.

E. Retaining walls. Construction details must be provided for all retaining walls greater than two feet in height. Retaining walls in excess of four feet exposed height shall be located as far as necessary from the property line to accommodate structural components. In addition, retaining walls more than three feet exposed height shall be designed according to the International Building Code, and calculations sealed by a professional engineer registered in the State of Delaware shall be submitted for review and approval by the Town.

F. Minimum slopes. The minimum slope, beyond the protective slope shall be 5/10% on impervious surfaces, 1% on all other pervious surfaces. When acceptable to the Town, the grade on pervious surfaces may be reduced to 5/10, provided that soil testing and assessment by a qualified professional are provided to ensure adequate infiltration potential is available through all layers of the soil horizon and that the local water table characteristics are amenable to such practices. It must be demonstrated that the lesser gradient is adequate to drain the lot without detrimental effect upon buildings or upon essential uses. Conditions that result in standing water for in excess of 24 hours are not acceptable, except in areas where delineated wetlands are shown on the lot.

§ 132-3 Lines and grades approval.

An overall lines and grades approval shall be required prior to approval of the subdivision or land development application.

A. Approval phases.

(1) Phase 1. The first phase of this approval shall be a detailed drainage design with calculations showing that full development of the upstream basin has been considered in sizing all drainage structures associated with the development. The drainage calculations and drainage plans shall be submitted to the Town for review. At the option of the applicant, a single plan satisfying drainage and lines and grades may be submitted.

(2) Phase 2. The second phase of this approval shall be the submission and approval by the Town of a detailed lines and grades plan. The grading plan shall be signed and sealed by the engineer or land surveyor.

B. Required information. The scale of the lines and grades plan shall be sufficient to provide the following in a clear and legible manner:

(1) Contours or existing grades at intervals of not more than one foot. If the average slope of the site is less than 1%, contour intervals shall be 1/2 foot. Contours lines shall be supplemented with spot elevations sufficient to determine high points, low points and to determine that there is adequate slope throughout the site.

(2) Location of house, structure and accessory buildings on each lot.

(3) Identification of each lot by number.

(4) Elevations shall be based upon the USC and GS (United States Coast and Geodetic Survey) data. The type of data and the location of the benchmarks shall be indicated on the submission.

(5) The final grade elevations or contours of the proposed finished grades shall be shown, including all drainage swales.

(6) Location of drainage outfall if any drainage is not to a street.

(7) Indication of the type of sanitary system to be used by the structure, i.e., county sanitary sewer; also, the method and by whom this system will or has been approved.

(8) Indicate where applicable the one-hundred-year flood line, either storm or tidal, with elevation of said lines to be shown.

(9) Complete metes and bounds data on the property with bearings and lengths of all lines including all necessary easements.

§ 132-4 As-built plan required.

Before granting a certificate of occupancy, an as-built survey plan must be submitted to the Town and reviewed by the Town Engineer for conformance with the approved site grading plan. The Town must approve the individual lot as-built plan before issuance of a certificate of occupancy for said property.

§ 132-5 Inspections.

In addition to any inspections performed by the Sussex Conservation District, the Town may periodically inspect the sites of land-disturbing activities for which permits have been issued to determine if the activities are being conducted in accordance with the plan and if the measures required in the plan are effectively controlling erosion and sedimentation.