1. Document through accepted engineering practices the impacts of the proposed development. At a minimum, documented impacts of the proposed development shall include:
a. Effects on existing upstream and/or downstream drainage systems and property;
b. Ability of the natural drainage way to handle additional storm water runoff; and
c. Site specific criteria supporting the analysis of any impacts notes in (a) and (b). above.
2. Demonstrate through accepted engineering practices that stormwater runoff is adequately conveyed through the development in a drainage system designed to meet the criteria described in the storm drainage standard details.
3. Demonstrate through accepted engineering practices that stormwater facilities required to control the impacts of the development are designed to meet the criteria described in the city's stormwater management program.
4. Demonstrate that the nitrogen and phosphorous loading from the new development does not exceed the limits set forth in this division.
5. Stormwater management plans shall be prepared by, and bear the seal and signature of, a licensed professional engineer, registered landscape architect, or registered architect.
6. Include drawings, maps, and supporting calculations, specifications, and summaries as outlined in the city stormwater program for nutrient control and below:
a. The type and design of each proposed stormwater facility. This includes grading, elevations, and other information sufficient for construction of each stormwater facility. Plans and profiles (if required) for each proposed stormwater facility must be included as well with any specific detail and notes required for construction.
b. The location, extent, type of use, and impervious areas of the development site conditions. This includes the following, but not limited to:
i. Watershed information (information for specific classified stream per this division).
ii. Specific river basin where the project is located (Tar-Pamlico or Roanoke River Basins).
iii. Pre-development impervious areas.
iv. Post-development impervious areas.
v. If the development will utilize the offsite option, clear demonstration that the proposed facility drains to the same stream as the proposed development site.
vi. Flood zone (if applicable).
vii. Buffer zone areas (if required per this division).
viii. Drainage map for development.
c. Calculations shall be sealed by the design professional and include, but not limited to, the following:
i. Stormwater narrative. This includes a detailed description of the existing site conditions, the proposed site conditions and the stormwater facility required to meet this division.
ii. Design calculations for each stormwater facility. This includes any design forms required by DWQ to be utilized in the stormwater BMP manual.
iii. Pre vs. post-development runoff calculations for one-year-24-hour storm for design and an analysis of the ten-year-24-hour, 25-year-24-hour and 100-year-24-hour storms.
iv. Drainage calculations for storm sewer and drainage ditches with hydraulic grade lines/capacity, etc. to ensure adequate capacity of proposed and existing downstream infrastructure.
v. Hydrology/hydrographs for BMPs.
vi. Nutrient management calculations.
vii. Buoyancy calculations (if required).
viii. USGS 7.5-minute quadrangle with the project location depicted on the map.
ix. NCRS Soils Survey map. The soils survey map must be from the latest, printed map from NRCS for the county. The computer version can be used for determination of soil type, but cannot be used for buffer determination.
x. Drainage map for the development with subdrainage information to each facility.
xi. Operation and maintenance plan for each facility.
1. A licensed professional shall certify that the constructed BMP is in substantial compliance with the approved construction document prior to issuance of post-construction stormwater permit.
2. For new construction, the certification will be required prior to issuance of a certificate of occupancy in addition to the post-construction stormwater permit.
3. As-built survey required. Prior to release of a certificate of stormwater compliance, as built surveys shall be required as follows:
a. The survey shall include the entire legal lot of record showing all impervious surfaces, building footprints, required buffers and any encroachments therein. Such survey shall include an information block totaling the percent of impervious coverage, the amount of impervious coverage on the site in square feet, building footprints, required buffers and any encroachments therein, and all constructed BMP's. Such survey shall include topography at two-foot contours.
b. The survey shall compare acreages of the various land covers as constructed to those permitted. If substantially different, the survey shall provide calculations demonstrating compliance with nutrient export requirements of section 16-37.5. If this is not the case, the owner shall amend the permit and make on-site or off-site adjustments accordingly to achieve the required export.
c. Stormwater conveyances. Any development that results in the construction or alternation of stormwater conveyance shall submit an as-built survey showing the location, extent, dimension and type of each conveyance.
d. Submission of the survey shall be in NAVD 1988 and NAD 1983 State Plane Coordinates, North Carolina Datum with the following:
i. One (1) hard copy (mylar or velum) with a signed certificate stating compliance and substantial completion of the stormwater facility to the approved stormwater management plans.
ii. One (1) electronic form of the survey in either .dxf or .dwg format.
A written agreement shall be submitted by the applicant, approved by the stormwater administrator, and recorded in the office of the register of deeds of the county prior to the issuance of a post-construction stormwater permit. Such agreement shall:
1. Be legally binding on all current and future parties in interest for all properties served by the BMP as covenants running with the land.
2. Identify the maintenance and monitoring requirements required to ensure the proper function of the BMP. Maintenance activities must meet or exceed the actions and frequencies identified by practice in the stormwater BMP manual. Such operations shall be specific to each BMP for the development. The operation and maintenance plan submitted under the stormwater management plan can be attached and utilized for this agreement.
3. A requirement that the owner of the permitted BMP submit an annual maintenance inspection report to the stormwater administrator by end of September of each year prepared and sealed by a qualified professional licensed in the state. Such report shall not be required for the first partial year if the initial certificate of stormwater compliance was issued for the BMP within six (6) months of the required deadline for submittal. Subsequent repairs and alternations to the BMP requiring a stormwater permit and certificate of compliance shall not alter the submittal requirements for an annual maintenance inspection report.
4. (4) A requirement for the establishment and maintenance of an escrow account that can be used solely for the routine maintenance, repair, restoration, reconstruction, removal, and/or replacement of a required BMP. In the case of multiple BMPs covered by an escrow account, the specifics for each BMP covered by the account shall be included. The escrowed amount shall be one hundred (100) percent of the total cost to construct each BMP. The agreement shall include the following:
a. The amount of the escrow fund.
b. A statement that if the city issues a NOV ordering the correction, repair, replacement, or maintenance of the system or structure and the owner fails to take all necessary actions to remove the violation or initiate an appeal within the time prescribed, the city or its contractor may have full access to the property to complete any action necessary to correct the violation.
c. A statement that the city may, upon order of other official action of the city council seize all or part of the escrowed funds to pay for all costs associated with the correction of the violation including administrative costs borne by the city.
d. A written commitment that the owner(s) (and his successors in title) will refund the escrow to the original amount prior to utilization by a lump sum or by specified time payments.
5. Records of installation and maintenance. The operation and maintenance agreement shall stipulate that parties responsible for the operation and maintenance of a stormwater management facility shall make and keep records of the installation and of all maintenance and repairs, and shall retain the records indefinitely. Whenever the party(ies) responsible for the operation and maintenance of a facility cease to exist, such records shall be transferred to the city. As long as records are maintained privately, they shall be made available to the city or its agents during inspection of the facility and at other reasonable times upon request.
6. A legal description or reference to the easement for each stormwater facility utilized by the development.
1. An easement shall be placed to encompass each entire stormwater facility, allowing access and room for maintenance of each facility. The easement shall further provide access to the nearest convenient public right-of-way and must be accessible by maintenance equipment.
2. The easement map shall be generated by a professionally licensed surveyor, signed by the owner, approved by the city and recorded in the county's register of deeds office. A copy of the recorded easement map shall be provided to the stormwater administrator for the city's files.