NC0084425_Staff Report_19941026

NPDES DOCUMENT :;CANNING COVER SHEET
NPDES Permit:
NC0084425
Davidson Water WTP
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Engineering
Alternatives (EAA)
Staff Report
Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Permit
History
Document Date:
October 26, 1994
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cc: Permits and Engineering
Technical Support Branch
County Health Dept.
Central Files
WSRO
SOC PRIORITY PROJECT: Yes No X
If Yes, SOC No.
To: Permits and Engineering Unit
Water Quality Section
Attention: Susan Robson
Date: October 26, 1994
NPDES STAFF REPORT AND RECOMMENDATION
County Davidson
Permit No. NC0084425
PART I - GENERAL INFORMATION
1. Facility and Address: Davidson Water, Inc.
P. 0. box 969
Welcome, N.C. 27374
2. Date of Investigation: October 19, 1994
3. Report Prepared by: Abner Braddy
03-o 7-04
U_-c• \IA bAct,a -
4. Persons Contacted and Telephone Number:
Mr. Gregg Stabler, General Manger, [phone]
Mr. Ron Farnsworth, Plant Superintendent, [phone]
Mr. Campbell Wallace, Engineer, [phone]
5. Directions to Site: From Winston-Salem, travel Hwy. 52
South to Hwy. 64 West; travel Hwy. 64 West to S.R. 1186;
turn left on S.R. 1186; the plant will be located on the
right, approximately .3 mile down S.R. 1186.
6. *Discharge Points(s), List for all discharge points:
Latitude: 35° 51' 08" Longitude: 80° 23' 05"
Discharge is upstream of raw water intake.
U.S.G.S. Quad No. D17SW U.S.G.S. Quad Name Churchland
7. Site size and expansion area consistent with application?
Yes No If No, explain: No site size asked for nor
given in the application; the site visit indicated that
there is adequate area to accommodate the project.
8. Topography (relationship to flood plain included): The site
is on level ground, and is within the flood plain of the
Yadkin River.

9. Location of nearest dwelling: The nearest dwelling is
approximately .3 mile from the site.
10. Receiving stream or affected surface waters: U.T. Yadkin
River
a. Classification WS IV C.A.
b. River Basin and Subbasin No.: Yadkin 03-07-04
c. Describe receiving stream features and pertinent
downstream uses: Davidson Water proposes to discharge
into an existing dry ditch upon their property. The
ditch would convey the discharge approximately 1000'
north to the unnamed tributary, which then flows
approximately 1000' west to the Yadkin. Approximately
24 miles downstream are the backwaters of the High Rock
Lake impoundment of the Yadkin. The next municipal raw
water intake downstream is that of the City of
Salisbury.
Part II - DESCRIPTION OF DISCHARGE AND TREATMENT WORKS
1. a. Volume of Wastewater to be permitted: _5 MGD (Ultimate
Design Capacity)
b. What is the current permitted capacity of the Waste
Water Treatment facility? Not currently NPDES
permitted.
c. Actual treatment capacity of the current facility
(current design capacity)? N.A.
d. Date(s) and construction activities allowed by previous
Authorizations to Construct issued in the previous two
years. N.A.
e. Please provide a description of existing or
substantially constructed wastewater treatment
facilities; N.A.; The water treatment plant currently
recycles its filter backwash water.
f. Please provide a description of proposed wastewater
treatment facilities. Permittee proposes to construct
two 291,000 gallon decant ponds, and an as yet
undetermined number of sludge drying beds.
g. Possible toxic impacts to surface waters: The discharge
would contain Aluminum Sulfate, Chlorine and a water
treatment compound known as C-9, produced by Calgon.
C-9 does not appear on the June 30, 1993 list of non-
biocidal compounds assembled by the Aquatic Toxicity
NPDES Permit Staff Report
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Unit. The permittee indicates that the Residual
Chlorine concentration of the discharge would be <.5
mg/l.
h. Pretreatment Program (POTWs only): N.A.
in development approved
should be required not needed __
2. Residuals handling and utilization/disposal scheme:
a. If residuals are being land applied, please specify DEM
Permit No.
Residuals Contractor
Telephone No.
b. Residuals stabilization: PSRP PFRP
Other
c. Landfill: The dried alum sludge will likely be
disposed of at the County landfill.
d. Other disposal/utilization scheme (Specify):
3. Treatment plant classification (attach completed rating
sheet) . I
4. SIC Code(s): 4941
Primary 21 Secondary
Main Treatment Unit Code: 5 0 0 . 1
PART III - OTHER PERTINENT INFORMATION
1. Is this facility being constructed with Construction Grant
Funds or are any public monies involved. (municipals only)?
No
2. Special monitoring or limitations (including toxicity)
requests: None
3. Important SOC, JOC or Compliance Schedule dates: (Please
indicate) N.A.
Submission of Plans and Specifications
Begin Construction
NPDES Permit Staff Report
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Date

Complete Construction
4. Alternative Analysis Evaluation: Has the facility evaluated
all of the non -discharge options available. Please provide
regional perspective for each option evaluated.
Spray Irrigation:
Connection to Regional Sewer System:
Subsurface:
Other disposal options: As previously noted, the water
treatment plant currently recycles its filter back -wash
water. They may continue to do so even if the NPDES permit
is issued.
5. Other Special Items:
PART IV - EVALUATION AND RECOMMENDATIONS
This is a typical surface water treatment plant. Raw water
is pulled from the Yadkin River and pumped to one of two holding
cells. The water is then chlorinated, routed through flash
mixers where Aluminum Sulfate is added for coagulation and Sodium
Hydroxide is added for pH adjustment. From the flash mixers,
water is routed to one of six settling basins; from the settling
basins, water is routed through one of 12 mixed media (sand and
coal) filters. The potable water is then treated with
Fluosilicic Acid (Fluoride) and, if sufficient Residual Chlorine
remains, enters the distribution system. If there is not
sufficient Residual Chlorine, the water is re -chlorinated.
The wastewater generated at the facility results from the
back -washing of the mixed media filters. At its present water
treatment capacity of 12.0 MGD, the filters are back -washed every
40-60 hours, dependent upon raw water quality with an average
backwash flow of 120,000 g.p.d. With the expansion of the plant
to 20 MGD, and the construction of more settling basins and 8
additional filters, that flow will, of course, increase. The
backwash water will flow to the 192,000 gallon decant ponds (2)
and will then be discharged.
NPDES Permit Staff Report
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The Region recommends the Permit be issued.
Sig re of report preprer
ater Quality Re-onal Supervisor
Date
a2, /Fr
NPDES Permit Staff Report
Version 10/92
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