20100251 Ver 2_Staff Comments_20110104

10-0251v2 Harnett Health Hospitals
AML Comments
January 4, 2011
1. Soils tests documenting the levels of the seasonal high water table (SHWT) for the four BMPS
serving Brightwater Biotechnology and Medical Center must be provided. If the soil test
indicates that the level of the SHWT is not within six inches of the one or more of the proposed
permanent pools of the BMPs, then an appropriate remedy must be provided per the NC BMP
Manual.
For BMP #2 serving the proposed Harnett Health Hospital, the proposed permanent pool of the
wet detention pond (172.5) is well above the estimated level of the SHWT (174.00). The DWQ
will not accept this design as it likely to result in dewatering of the groundwater table as well as
a loss of storage in the BMP. The DWQ recommends that this device be converted to a
stormwater wetland, which will result in a much more shallow excavation and reduce the depth
of the temporary pool.