(a) The requirements and standards of this section shall apply to all new development and re-development projects within the corporate boundaries of the Town of Granville.
(1) The following activities shall be exempt from the requirements of this section, except that no activity shall be exempt from the management of the discharge of sediment or any other form of water pollution that may leave any parcel or site.
A. Additions or modifications to existing detached single-family dwellings of a size less than 1,000 square feet.
B. Activities that result in an impervious area of less than 3,000 square feet, unless that activity results in creating a parcel with less than 10% of the parcel in green space. The current Zoning phased construction projects shall be measured by the total of all planned or contemplated phases. Each phase may be required to meet the requirements of the article.
(2) All new and re-development projects subject to the provisions of this article shall be required to obtain a Stormwater permit from the Town of Granville. The Town will not issue a Building permit without an approved Stormwater permit. The Town will not issue a Certificate of Occupancy without "As-Built" documentation of the stormwater system and a recorded Maintenance Agreement for said system.
(b) Uniform requirements shall be applied to each regulated project site.
(1) The Town of Granville NPDES Permit, when the town is issued one, will require that sites disturbing 1 acre or more must 100% manage, with no discharge to surface waters, the first one inch of rainfall from a 24-hour storm proceeded by 48 hours of no measureable precipitation. Runoff volume reduction can be achieved by canopy interception, soil amendments, evaporation, rainfall harvesting, engineered infiltration, extended filtration and/or evaporation and any combination of the aforementioned practices. Flows above the first one inch can be discharged based upon the criteria that post development stormwater peak runoff rates must be reduced by 10% from pre-development runoff rates.
(2) Stormwater Permit Requirements:
A. Drawing Descriptive Information:
1. Title block with the development name, owner’s name, design firm , scale, sheet numbers, and date, legend, north arrow, vicinity map, revision numbers and dates.
2. Topographical Features: Original contours no greater than 2' vertical contours, existing drainage components (streams, ponds and rivers), property boundary , existing streets, buildings and utilities, and any off-site drainage entering site. A 100-year flood plain map may be included on a cover page or with the written portion of the permit.
3. Site Plan Drawing(s): Original drawings no larger than 24" x 36" and at a scale from 1"=10' to 1" = 50' All drawings and calculations to be signed by a registered WV Professional Engineer.
a. Existing and proposed structures, roads, buildings, and paved areas.
b. Existing and proposed stormwater management system and components including sizes, lengths, pertinent elevations, etc.
c. Where and how the proposed stormwater management system will be connected to the existing system.
d. Locations and grade of all swales including cross sections.
e. Location and design of all other Best Management Structures/Implementations.
f. Sediment and Erosion Control measures are required. Refer to the West Virginia Erosion and Sediment Control Best Management Practice Manual for acceptable means and methods.
g. Existing and proposed ground cover.
h. Total Impervious area.
i. Control release facilities showing cross-sections and profiles.
4. Final As-Built Drawings:
a. Submit two sets of signed original drawing and submit an Autocadd DXF or DWG file format (2000 – 2008 version).
b. Show all revised contours and appropriate "spot elevations".
c. Show location, length, sizes, pertinent elevations of the storm water system.
d. All impervious areas shall be accurately depicted.
e. No Certificate of Occupancy will be issued if final as-built drawings and files are not received. Further legal enforcement will be taken if these drawings and files are not received and the owner puts the property into use and the owner will be held responsible for all related charges.
(3) Design Standards:
A. Flow rates shall be calculated by use of the Rational Method unless sufficient justification for use of another method is approved by the Town's Engineer.
B. The minimum "Time of Concentration" to be used in the calculations shall be six (6) minutes.
C. The ABT and Grigg Method shall be used to determine the volume necessary for the detention.
The volume for detention shall not include the volume needed for retention in structures designed for projects having a disturbed area of an acre or more. Detention structures shall be designed in such a manner that a peak runoff rate of flow shall have a reduction of 10% from the pre-existing peak runoff rate for the 2-year/24-hour, 10-year/24-hour and 25-year/24-hour storms. Should the project discharge into a system already experiencing flooding issues the discharge flow reduction may be increased or the developer shall be required to upgrade the storm water piping system to accommodate the increased flow at their expense or the project will be denied a permit.
D. All development projects shall minimize the impact to the water environment by applying structural and/or non-structural management practices selected to address site-specific conditions. The minimum requirement for runoff water quality treatment shall be a reduction of 80% of the average post-development total suspended solids and a reduction of 40% of the average post-development phosphorus load.
E. No construction shall be performed in a manner that will negatively impact the water environment in the vicinity of the construction or in other areas, regardless of whether this impact is manifested by flow restrictions, increased runoff, diminished channel or floodplain storage capacity, harm to aquatic life or any other manifestation of negative impact.
F. Any construction shall be permitted only after temporary or permanent erosion and sediment control management practices have been placed and are operational to the satisfaction of the Building Inspector and/or Engineer. The Building Inspector and/or Engineer may halt construction, void a permit, or take other enforcement actions consistent with this article upon a finding of inadequate erosion and sediment control management practices upon a site or property subject to the provisions of this article.
G. All active construction sites shall be inspected by the owner no less than weekly and within 24 hours after a 0.25 inch rain event to ensure and verify effective erosion and sediment control. The owner shall maintain records of these inspections. The Building Inspector and/or Engineer may halt construction on properties that do not provide satisfactory proof of compliance with this requirement.
(c) Construction Site Run-off. This section will require the site plans to show all proposed erosion and sediment controls, silt fence, inlet protection, construction entrance etc. as appropriate for the construction project to keep sediment out of the storm water system.
The plans must also detail reclamation details for the site, seeding, mulching and other re-vegetation practices and materials.
(1) Owners and Contractors must be held responsible for:
A. Controlling waste;
B. Showing proof of other necessary permits, NPDES, WVDOT, and Health Department etc. as appropriate for the site;
C. Utility coordination;
D. The Town must make allowance for adequate site inspections and enforcement (if in non-compliance they are shut down);
E. Pre-construction meeting to review E and S, routine inspections during job with reports generated on each and any actions needed;
F. Dumpster pad and enclosures for commercial applications (multi-family units and food service must have drain tied into sanitary per WVDHHR);
G. Cleanouts as per attached drawing;
H. Maintenance agreement on all detention/retention systems;
I. Domestic water;
J. Separation of water and gas lines (6' horizontal & 18" vertical);
K. Water and gas may be placed in the same trench with a 2' hor. separation;
L. Separation of water and sewage lines (10' horizontal & 18" vertical with water on top);
M. Separation of water and underground electrical lines (18" horizontal and 18" vertical) 10' hor. is preferred;
N. Water lines should be cased under roads and driveways with at least sch. 40 PVC pipe twice the diameter of the line, where heavy traffic may occur use sch. 80 PVC;
O. Sanitary lines same as above;
P. New sanitary lateral service connections must be installed by the WV Department of Health and Human Resources Regulations and have a clean out installed at the property line;
Q. Any new sanitary laterals for single family homes must be 4" SDR-35 or sch. 40 PVC;
R. Any new sanitary laterals for commercial hookups or multifamily units must be 6" SDR-35 or sch. 40 PVC and have cleanouts at the building and the property line. Depending on the configuration of the sanitary line layout cleanouts may be required at any change of direction in the line and the end of lines;
S. Straight cleanouts should be used. A frame and cover shall be required when cleanouts are located in a sidewalk and paved or concreted area. (Passed 12-13-11.)