The Town of Garner regulates two stormwater permits, which dictate stormwater rules that developers must follow. These permits include the Neuse Rules for Nitrogen Control as well as a MS4 NPDES Phase II permit. In addition to these two permits, Garner is also located in a watershed water supply area. A large majority of the town drains to Lake Benson, which is a drinking source for City of Raleigh customers and has an additional water quality requirement. Please see the linked map to determine if your site plan will fall within the watershed water supply protection area.
Water Supply Water Protection Program
Water Supply Water Protection Program Rules have been in effect since 1993. If your potential site falls within this area and drains to Lake Benson, you will be subject to treat your impervious surface with a primary stormwater control measure (one that has credit for reducing 85% TSS). If your impervious surface does not exceed twelve (12%) percent of the pervious area after 1993, you do not need to provide a water quality stormwater control measure for 85% TSS removal. If you exceed twelve (12%) percent impervious surface of the pervious area at the site (including whatever area has been developed since 1993), you will be required to implement a primary stormwater control measure for 85% TSS removal.
Neuse Rules for Nitrogen Control
The Neuse Rules were implemented in 2001, any impervious surface that predated the Neuse Rules is considered to be grandfathered in and you do not have to account for/treat it. Any impervious surface developed after 2001 will be subject to the nitrogen rules. Any commercial development may not exceed 10 pounds per acre per year after stormwater control measures and provide a buy down to the threshold of 3.6 pounds per acre per year. Any residential development may not exceed 6 pounds per acre per year after stormwater control measures and must provide a buy down to 3.6 pounds per acre per year. The nitrogen rules also require you to detain the 1 year storm. The nitrogen form links are below. Please use Method 1 for residential subdivisions and Method 2 for any redevelopment or new development of commercial sites and multi-family sites.
NITROGEN FORMS :
The Town of Garner also requires the developer to detain the 1, 10, 25 and sometimes 100 year (depending on location) storms with their implementation of new impervious surface unless it is shown that detaining water will negatively impact downstream areas. If the impervious surface added is equal to or less than 1% of the project site, then these rules may not apply.
MS4 NPDES Phase II
The NPDES Phase II permit is also similar to the Neuse Rules permit. Site plan review, public education, stormwater controls, erosion control and pollution prevention are all parts of this permit.
Stormwater Control Measures
If any stormwater control measures are implemented with a development site, you will be required to provide an O&M Agreement along with a Memorandum of Agreement that is required to be recorded with the Wake County Register of Deeds prior to obtaining a Certificate of Occupancy (for commercial) or at Plat Recordation (for residential subdivisions). You will also be required to submit as-builts and certification at the close of the projects as well. Stormwater control measures are subject to an annual Town of Garner inspection by Engineering staff for function and compliance with the approved site plan.
For any additional stormwater questions or concerns, please contact Jaclyn Stannard, Stormwater Program Administrator, firstname.lastname@example.org, 919-773-4421