(A) Water quantity credit. This credit has been retained from the SD1 credits program. Water quantity credits are available for properties that address hydromodification of receiving watercourses by controlling the rate at which post-development stormwater flow is discharged from the site. Credits are available for discharging post-construction stormwater flow at a rate equal to or less than the critical flow (Qcritical) of the receiving watercourse. Unless specific data is available for the receiving watercourse, Qcritical shall be 0.4 cubic feet per second (cfs) per acre for up to a two-year, 24-hour storm event using SCS Type II rainfall distribution. The maximum allowable credit available for reducing post-construction stormwater flow rates to Qcritical is 40%.
(B) Water quality credit.
(1) Water quality credits are available for properties that implement post-construction facilities, best management practices (BMP), green management practices (GMP) or low impact development (LID). The city is suggesting ten management practices from the Storm Water Best Management Practices Manual - Sanitation District No. 1 of Northern Kentucky that may be desirable for the city. The ten practices are listed below and the best management practices manual has the selection, design, construction, and maintenance criteria and standards to implement these practices. There are other practices contained in the BMP manual that may be used, however, the practices listed below should be considered first. The core management practices and the percentage credit available are as follows:
Core management practice
| Percentage credit available |
Core management practice
| Percentage credit available |
Biofiltration swale | 10% |
Bioretention/rain garden | 20% |
Extended detention basin (dry pond) | 30% |
Gravity separator | 30% |
Permeable pavement | 20% |
Planter box | 20% |
Retention basin/wet pond | 40% |
Street trees | 10% |
Subsurface vaults | 30% |
Vegetated filter strip | 10% |
(2) The city will consider other management practices (BMPs, GMPs, LID), however, they must be approved by the City Stormwater Department.
(C) Education credit. Education credits are available for educational institutions such as public schools, private schools, colleges and universities. Organizations must develop and annually implement a city water quality educational program that addresses specific environmental issues at the expense of the applicant. The maximum credit percentage for education is 50%.
(D) Gravel credit. The city stormwater district considers all compacted gravel areas (drives, storage areas, and the like) as impervious areas, and includes these surfaces in calculating the stormwater fee. The city acknowledges that gravel surfaces do allow for the infiltration of stormwater flow in a slightly different manner than imperious surfaces. Therefore, an allowance for gravel surfaces on a case-by-case basis for these surfaces will be offered. It is up to the non-residential property owner of these properties to submit a credit application in order to receive credit for gravel surfaces. The credit shall only apply to the gravel area of the property and not all impervious areas of the site. The gravel credit is subject to an on-site review to be performed by the city to make the final determination prior to any credit approval. The maximum credit percentage for gravel is 10%.
(E) Water quality LEED credits. Developments and parcel owners within the city that have been awarded the LEED® certification (based on the U.S. Green Building Council, Inc. LEED® Certified Development Rules and Regulations) that have earned credits from the LEED certification process may also qualify for a credit reduction regarding the stormwater charge if the following criteria are met (submission of the LEED certification notice to validate the application and measure the amount of stormwater control is required to be submitted in conjunction with this stormwater credit application). Please refer to the LEED website for more information at http://www.usgbc.org/.
(1) The sustainable sites category of stormwater design quantity control contained in the LEED certification process may be eligible for a 25% reduction in the stormwater charge; and/or
(2) Stormwater design quality control rate and quantity reduction contained in the LEED certification process may be eligible for up to a 50% reduction in the stormwater charge (with the assumption that a 50% maximum credit is allowed per property as described above).
(Ord. 14-1003, passed 5-12-14)