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Frequently Asked Implementation Questions


While no two sites are the same, we have tried to provide answers to general questions.  The answers are to be used as general guidance, and individual site conditions may dictate a different interpretation by City staff.

1. If there is an approved set of construction plans that show full build out of a site, but not all of the buildings have been built, is the site "grandfathered"? Provided that the site was designed for full build out and all storm water controls were designed and constructed under the applicable ordinance that was current at the time of approval, the site may be considered for a one time "grandfathering," because that impervious has been permitted.  Any deviation from the approved plan or redevelopment of the site may subject the site to the redevelopment provisions of the ordinance.  These sites will be reviewed on a case-by-case basis.

2. If an existing BMP is designed for future additions to the site, will it need to undergo a retrofit in order to meet the PCCO? Projects exist where BMPs serve multiple buildings and/or parcels, some of which have not been completed.  These projects will not be required to retrofit existing ponds of other BMPs to meet new requirements, provided that BMP was originally designed and built to serve existing and proposed impervious areas under the applicable ordinances at the time of BMP approval.  Sites increasing impervious coverage and rezonings intensifying the site may be subject to additional controls.

3. Do proposed public streets internal to a proposed development require treatment? Yes, proposed streets being built by development shall be considered as part of the new impervious area on sites subject to the PCCO. 

4. Are public streets that remain undisturbed except for routine maintenance in a development project subject to PCCO? Public streets that remain undisturbed do not have to be treated.   However, if the street water flows through the BMP the street area must be considered in the BMP design.  Another approach would be to bypass the street water around the BMP. 

5. Are routine maintenance activities subject to PCCO? Any impervious surface that remains and is not disturbed (i.e. – scraped clean and rebuilt) can forego treatment as long as the activity performed on the impervious surface is considered routine maintenance.  Examples of maintenance include repaving a street or parking lot or rebuilding the façade of a building for aesthetic purposes.

6. Does the detention ordinance still apply to development and redevelopment? The Detention Ordinance has not been taken out of the Zoning Ordinance, so a 1978 snapshot of impervious cover will remain the benchmark for projects being in compliance with the Detention Ordinance.  Even if the PCCO is not applicable to a project, the 20,000 sf threshold for detention is still applicable.

7. Are there peak control requirements for Low Density Single Family Projects? Since the PCCO does not require peak control for low density developments and the detention ordinance has not been applied to single-family developments, low density single-family developments will not be required to provide detention.

8. Is there a difference between Impervious Area and Built Upon Area? For the purposes of the PCCO, built upon area includes all impervious area plus other modifications to existing ground such as artificial turf that decrease the infiltration of storm water.  For the sake of the PCCO, gravel is considered an impervious surface.

9. What are the water quality requirements for additions to sites with existing impervious areas? Similarly to the way impervious areas are treated for peak control, water quality treatment for additions will only be required on the impervious areas that are added.  Treatment of existing impervious areas that are to remain is not required unless runoff from existing area goes to a BMP.

10. Can BMPs count as Natural Area? Generally, areas within the Post Construction Controls Easement cannot be counted as Natural Area, due to the area being needed for maintenance of the BMP.  Area that is not needed for the maintenance of the BMP will be evaluated on a case-by-case basis.

11. How is redevelopment area calculated for purposes of controls and mitigation fees? The controls and mitigation fees to be paid are based on the post-developed impervious area of the site, not the entire site area.  Natural area mitigation fees are based on the mitigated area, not the entire site area.

12. What activities are allowed in undisturbed buffers? All buffer requirements in the PCCO refer to the S.W.I.M. Ordinance, which describes what activities are allowed.  Parallel water and sewer utility installation as approved by Charlotte-Mecklenburg Utilities are permitted, as are road crossings for connectivity or transportation links where the Charlotte-Mecklenburg Planning Commission has granted site plan approval.  Please note that BMPs used to meet PCCO requirements are not allowed in the undisturbed buffer.  At this time, no disturbances are allowed to buffers on intermittent and perennial streams in the Six Mile basin.

13. Are stream buffers required in low density projects? Yes, the watershed district standards in the PCCO require stream buffers for low density projects.

14. Can existing BUA be treated in lieu of treating new BUA? Generally, yes.  The BUA size to be treated must be greater than or equal to the area being added and both areas must drain to the same discharge point.   Treatment trading is not allowed if the new BUA is vehicle related impervious and the existing BUA is rooftop and in other possible scenarios where it is determined that water quality benefits may be negatively impacted by the trade.  Consult the land development engineer prior to submitting plans to ensure that the treatment trading will be allowed.

15. What about BMPs not listed in the BMP Manual? The City will adopt standards for BMPs that are not on the approved list if our Pilot BMP program provides conclusive results that such systems meet the goals set forth in the Ordinance and are feasible long-term; however, at this time each system will be viewed as proprietary and will be subject to those provisions for proprietary systems.  Contact the Storm Water Ordinance Administrator if you are proposing the use of a proprietary system.  These will be accepted only on a case-by-case basis, and these BMPs may be subject to additional requirements including, but not limited to, additional documentation, testing, and backup plans.

16. Are green roofs allowed? See Section 4.10 of the BMP Design Manual for green roof applications.