19970722 Ver 1_More Info Received_19970819

PIEDMONT TRIAD REGIONAL
August 18, 1997
Pete Colwell 1997
PI1
NCDENR a`IO
4401 Reedy Creek Rd. ENVIP NMI!viH;-JyIENCE
Raleigh, NC 27607
Dear Pete:
W AT E R AUTHORITY
As we discussed on the phone, the PTRWA Board of Directors is interested in your agency's
position on the potential success of our proposed wetland mitigation sites, specifically the
Reddick's Creek Site.
For your review and evaluation I have enclosed the following information:
1. The soil evaluation done on each of the five proposed sites
2. The Reddick's Creek Soil Boring Descriptions
3. A preliminary design plan for four of the five sites (Richland Creek, Hickory Creek,
Muddy Creek, and Reddick's Creek)
4. A summary of the current estimates of existing wetlands and potential credit area
of the five sites
If you need any other information, please let me know. I appreciate your help on this issue and
look forward to hearing from you soon.
Sincerely,
O?a_ -1? .
Andrea M. Spangler
Environmental and Special Projects Manager
Enclosure
Wilmington Building, Suite 207 • 2216 West Meadowview Road • Greensboro, North Carolina 27407-3480
Telephone: [phone] • FAX: [phone]
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110
Preliminary Estimate'
Groundwater Discharge Zone of Influence on Wetland Hydroperiod
Chewacla Soil
Floodplain Groundwater Number of Groundwater Number of
Surface Elevation Discharge Zone Years Discharge Zone Years
Above of Influence3 Wetland of Influence Wetland
Channel Invert / (feet) Criteria Met (feet) Criteria Met
Weir Heightz (Surface (Surface
(feet) Hydroperiods <5% Hydroperiods <
of the growing 12.5% of the
season) growing season)*
Forested Conditions
(relatively high surface water storage and rooting functions)
0 ----- 29/31 ----- 27/31
1 253 20/31 145 16/31
2 85 16/31 225 16/31
3 125 16/32 275 17/31
4 160 16/31 315 16/31
6 215 16/31 380 16/31
8 245 16/31 405 16/31
1 : Average groundwater slope perpindicular to a stream channel has been estimated based on general experience in
Piedmont systems. Actual groundwater slope during the early growing season varies significantly in Piedmont
bottomlands.
1 : Soil hydraulic conductivities and drainage rates have been generalized based upon limited data and regional
averages.
2: "Weir Height" is assumed to represent the effective depth (invert) of the drainage feature.
3: Discharge Zone of Influence is equal to '/2 of the modeled ditch spacing
Preliminary Estimate'
Groundwater Discharge Zone of Influence on Wetland Hydroperiod
Congaree Soil
Floodplain Groundwater Number of Groundwater Number of
Elevation Above Discharge Zone Years Discharge Zone Years
Channel Invert / of Influences Wetland of Influence Wetland
Weir Height' Ifeet) Criteria Met Ifeet) Criteria Met
(feet) (Surface (Surface
Hydroperiods <5% Hydroperiods <
of the growing 12.5% of the
season) growing season)
Forested Conditions
(relatively high surface water storage and rooting functions)
0 ----- 27/31 ----- 19/31
1 55 '16/31 UA4 14/31
2 90 17/31 UA 14/31
4 145 16/31 UA 14/31
6 195 16/31 UA 12/31
8 215 16/31 UA 12/31
Fallow Field/Pasture Conditions
(relatively low surface water storage and rooting functions)
0 ----- 25/31 UA 6/31
1 120 16/31 UA 3/31
2 165 17/31 UA 3/31
4 240 16/31 UA 2/31
6 280 16/31 ILIA 2/31
8 305 16/31 UA 2/31
Average groundwater slope perpindicular to a stream channel has been estimated based on general experience in
Piedmont systems. Actual groundwater slope during the early growing season varies significantly in Piedmont
bottomlands.
Soil hydraulic conductivities and drainage rates have been generalized based upon limited data and regional
averages.
"Weir Height" is assumed to represent the effective depth (invert) of the drainage feature.
Discharge Zone of Influence is equal to % of the modeled drainage spacing
UA = wetland criteria unachievable
Piedmont Triad Regional Water Authority
Wetland Mitigation Sites
Aug-97

Site Original Est. Acreage Current Est. Acreage Existing Wetlands Credit Area
Richland Creek 47.6 51.4 13.3 38.1

Hickory Creek 42.2 37.8 3.9 33.9

Upper Muddy Creek 18 17.9 1.3 16.6

Reddicks Creek - Sumner Hills 47 25.3 2.1 23.2

Butke Diary Site 3

Totals 157.8 132.4 20.6 111.8

, ti? ? y97
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