STORM WATER MANAGEMENT

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					                                                    GWINNETT COUNTY
                                                STORM WATER MANAGEMENT
                                          REVIEW CHECKLIST – WATER QUALITY BMP
                                                 CONSTRUCTED WETLANDS




DEVELOPMENT NAME:

DISTRICT/LANDLOT/PARCEL:

ENGINEER:

FAX NUMBER/EMAIL:

REVIEWER:

DATE:

COUNTY CASE #:


 ...          Walk Through

 ...      Drop-Off, include a copy of these comments and one set of plans, do not drop off money or easement documents.
Bring to Suite 275- 2nd floor One Justice any day of the week. Allow up to 5 business days for re-review.

 ...   Section Re-Review, include a copy of these comments and one set of plans, do not drop off money or easement
documents. Bring to Suite 275- 2nd floor One Justice any day of the week. Allow up to 10 business days for re-review.

FYI if all comments are not addressed after the third review, a meeting will be required with County Staff, Designer and
Owner/Developer.


Constructed Wetlands from section 8-3-6 of the Stormwater Systems and Facilities Installation Standards and
Specifications (SSFISS)

1.     ...         Provide calculations showing that inflow to wetlands system is greater than that leaving the basin by
                   infiltration or exfiltration.

2.      ...        Minimum wetlands treatment capacity is the water quality volume (runoff from 1.2” of rainfall). Portion of
                   water quality volume treated by extended detention shall not exceed 50%. Use the following equation to
                   drain the runoff from the extended detention portion in 24 hours.

                   A = 0.6(V/t)(64.4*H/2) 0.5          where        t = 86,400 sec.
                                                                    A = area of the orifice, ft2
                                                                    H= height above the centroid of the orifice
                                                                    V = water quality volume, ft3

3.     ...         Provide a trash rack or other system to prevent clogging of the extended detention orifice.

4.     ...         The length-width ration shall be at least 2:1.

5.     ...         Provide calculations proving that the surface area of the wetland is at least 3% of the area of the watershed
                   draining to it.

6.     ...         Provide calculations showing that 75% of the wetland has water depths of less than 12” and 25% of the
                   wetlands has depths ranging from 2 to 3 feet.
GWINNETT COUNTY SWM – REVIEW CHECKLIST – CONSTRUCTED WETLANDS                                                           Page 1 of 2
REV 04/04 10/06.
7.    ...     The deeper area of the wetland shall include the outlet structure so outflow from the basin is not obstructed
              by sediment build-up

8.   ...      A forebay shall be established at the pond inflow points to capture larger sediments and shall be 4 to 6 feet
              deep. Direct maintenance access shall be provided to the forebay by a 15-foot access road at a maximum
              20% grade.

9.    ...     Provide energy dissipaters at inlets and outlet of the wetlands system, if those velocities exceed the non-
              erodable velocity of the channel.

10. ...       A total of five (5) wetland species shall be planted on the wetland. Two (2) of these shall be aggressive
              wetland species from the primary species list in figure 8-9 of the Stormwater Systems and Facilities
              Installation Standards and Specifications (SSFISS)and three (3) shall be from the secondary species list in
              figure 8-9 of the Stormwater Systems and Facilities Installation Standards and Specifications (SSFISS).


11. ...       Show calculations proving that 30% to 50% of the shallow area of the basin (less than 12” depth) shall be
              planted with wetland vegetation.

12. ...       Plans must show that 50 individuals of each secondary species shall be planted per acre; set out in 10 clumps
              of 5 individuals and planted within six feet of the edge of the pond (deep portion of the wetland) in the
              shallow area leading up to the ponds edge.

13. ...       A minimum 25-foot buffer shall be established and planted with riparian and upland vegetation.

14. ...

15. ...

16. ...

17. ...




GWINNETT COUNTY SWM – REVIEW CHECKLIST – CONSTRUCTED WETLANDS                                                      Page 2 of 2
REV 04/04 10/06.

				
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