NC0084425_Renewal (Application)_20161205

NPDES PERMIT APPLICATION - SHORT FORM C - WTP
For discharges associated with water treatment plants
Mail the complete application to:
N. C. Department of Environment and Natural Resources
Division of Water Quality / NPDES Unit
1617 Mail Service Center, Raleigh, NC 27699-1617
NPDES Permit Number INCO084425
If you are completing this form in computer use the TAB key or the up - down arrows to move from one
field to the next. To check the boxes, click your mouse on top of the box. Otherwise, please print or type.
1. Contact Information:
Owner Name
Facility Name
Mailing Address
City
State / Zip Code
Telephone Number
Fax Number
e-mail Address
Davidson Water, Incorporated
Davidson Water Plant
PO Box 969
Welcome
NC 27374
[phone]
[phone]
[e-mail]
2. Location of facility producing discharge:
Check here if same as above ❑
Street Address or State Road 388 Koontz Road
City Lexington
State / Zip Code NC 27295
County Davidson
3. Operator Information:
Name of the firm, consultant or other entity that operates the facility. (Note that this is not referring to the
Operator in Responsible Charge or ORC)
Name Davidson Water, Incorporated
Mailing Address PO Box 969
City Welcome
State / Zip Code NC 27374
Telephone Number [phone]
Fax Number [phone]
4. Ownership Status:
Federal ❑
State ❑
Private
Public ❑
Page 1 of 4 Version 5/2012

NPDES PERMIT APPLICATION - SNORT FORM C - WTP
For discharges associated with water treatment plants
5. Type of treatment plant:
® Conventional (Includes coagulation, flocculation, and sedimentation, usually followed by
filtration and disinfection)
❑ Ion Exchange (Sodium Cycle Cationic ion exchange)
❑ Green Sand Filter (No sodium recharge)
❑ Membrane Technology (RO, nanofiltration)
Check here if the treatment process also uses a water softener ❑
6. Description of source water(s) (i.e. groundwater, surface water)
Surface water pumped from the Yadkin River
7. Describe the treatment process(es) for the raw water:
Nutrient removal via alum, pre -sedimentation by impoundment using three separate reservoirs
operated in series. Pre -oxidation with chlorine dioxide. Clarification by coagulation, upflow
clarification, and filtration. Primary coagulant is ferric sulfate with polymer coagulant aid and
pH adjustment as necessary with sulfuric acid or sodium hydroxide. Water is disinfected with
chlorine gas. Zinc -Ortho -Phosphate corrosion inhibitor is applied, as is hydrofluosilic acid, and
additional pH adjustment as necessary with sodium hydroxide.
S. Describe the wastewater and the treatment process(es) for wastewater generated by the
facility:
Process sludge is dewatered and thickened with polymer. Decant water, filter backwash waste
and any additional process waste water are stored in two retention ponds typically operated in
series. New filters' backwash waste is directed to a holding tank which then feeds into the
retention ponds. Calcium thiosulfate applied as necessary for residual chlorine removal. Waste
lagoons gravity flow through a V -notch decant weir for flow measurement.
9. Number of separate discharge points: 1
Outfall Identification number(s) 001
10. Frequency of discharge: Continuous ® Intermittent ❑
If intermittent:
Days per week discharge occurs: Duration:
11. Plant design potable flowrate 30.000 MGD
Backwash or reject flow 0.375 MGD
12. Name of receiving stream(s) (Provide a map showing the exact location of each outfall, including
latitude and longitude):
Yadkin River
13. Please list all water treatment additives, including cleaning chemicals or disinfection
treatments, that have the potential to be discharged.
Page 2 of 4 Version 5/2012

NPDES PERMIT APPLICATION - SHORT FORM C - WTP
For discharges associated with water treatment plants
Alum / aluminum sulfate
Iron sulfate / ferrous sulfate
Fluoride
Ammonia nitrogen / Chloramines
Zinc -orthophosphate or sweetwater CP1236
List any other additives below:
Yes X No
Yes X No
Yes X No
Yes No X
Yes X No
Sulfuric Acid, Sodium Hydroxide, Chlorine Dioxide, Chlorine Gas, Polymer
14. Is this facility located on Indian country? (check one)
Yes ❑
III
15. Additional Information:
Provide a schematic of flow through the facility, include flow volumes at all points in
the water treatment process. The plan should show the point[s] of addition for
chemicals and all discharges routed to an outfall [including stormwater].
Solids Handling Plan
16. NEW Applicants
Information needed in addition to items 1-15:
New applicants are highly encouraged to contact a permit coordinator with the
NCDENR Customer Service Center.
Was the Customer Service Center contacted? ❑ Yes ❑ No
Analyses of source water collected
Engineering Alternative Analysis
Discharges from Ion Exchange and Reverse Osmosis plants shall be evaluated using a
water quality model.
17. Applicant Certification
I certify that I am familiar with the information contained in the application and that to the
best of my knowledge and belief such information is true, complete, and accurate.
Ron Sink CEO/ General Manager
Printedname o rson gning Title
Com- !l -
Signature of Applicant -
Date
North Carolina General Statute 143-215.6 (b)(2) provides that Any person who knowingly makes any false statement representation, or certification in any application,
record, report, plan, or other document files or required to be maintained under Article 21 or regulations of the Environmental Management Commission implementing that
Article, or who falsifies, tampers with, or knowingly renders inaccurate any recording or monitoring device or method required to be operated or maintained under Article 21
or regulations of the Environmental Management Commission implementing that Article, shall be guilty of a misdemeanor punishable by a fine not to exceed $25,000, or by
Page 3 of 4 Version 5/2012

NPDES PERMIT APPLICATION - SHORT FORM C - WTP
For discharges associated with water treatment plants
imprisonment not to exceed six months, or by both. (18 U.S.C. Section 1001 provides a punishment by a fine of not more than $25,000 or imprisonment not more than 5
years, or both, for a similar offense.)
Page 4 of 4 Version 5/2012

Davidson Water, Inc.
Davidson Water Treatment Plant .
State Grid/Quad:
D17SW /Churchland, NC
Sub -Basin:
03-07-04
Permitted Flow:
not limited
Stream Class:
WS -N; CA
Receiving Stream:
Yadkin River
Stream Segment:
12-(97.5)
Drainage Basin:
Yadkin —Pee Dee Basin
HUC:
03040101
Facility
Location
not to scale r.
y1
7 NPDES Permit NCO084425
NortYG Davidson Count

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DAVIDSON WATER, INC. MARZIANO & McGouGnx, P.A.
02 s g o w wrP UPGRADE SITE LAYOUT PLAN
_ o DaMson County, North Carolina
I� �W�

Mailing Address�_O�
Shipping Address
Davidson Water Inc.
DAI
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Davidson Water Inc.
P.O. Box 969
"AY
7040 Old Highway 52
Welcome, NC 27374
Lexington, NC 27295
Lexington [phone]
WATER INC�
Water Plant 787-5800
Winston-Salem [phone]
�
((336)
Office Fax [phone]
Thomasville [phone]
www.davidsonwater.com
email [e-mail]
WATER TREATMENT PLANT RESIDUALS MANAGEMENT PLAN
GENERAL
The Davidson Water Treatment Plant is a 30 MGD Water Treatment Plant divided into two trains. The primary train
consists of a 15 MGD Super Pulsator/conventional filter facility and the secondary train consists of a 15 MGD
settling basin utilizing lamella plates and sludge collection system/conventional filters.
Residuals are generated from the plants from two sources: 1) Residuals removed during the sedimentation phase of
the project, and 2) Residual removed by the filter. Listed below are descriptions for the generation, as well as
residual handling:
RESIDUALS GENERATED
15 MGD SUPERPULSATOR PLANT — The treatment process utilizes ferric sulfate and a polymer to precipitate
and coagulate impurities in the raw water supply. The residuals are continuously removed from the Super Pulsator
and pumped to a sludge thickener. The total residuals generated include the total suspended particles in the water, as
well as any precipitant generated through the use of the coagulant and the polymer.
SUPERPULSATOR FILTERS — Filters are backwashed on a routine interval based upon headloss in the filters. The
headloss is accounted for by any suspended particles that are collected on top of the filters. Backwash operations
remove these particles. The flow from the backwash process goes to the backwash equalization lagoon prior to any
residuals handling.
LAMELLA PLATE SETTLERS — In the conventional water treatment plant, the residuals are settled through the
use of lamella plate settlers. The residuals are removed continuously from the bottom of the sedimentation basins
where they are piped to the sludge thickener.
EXISTING PLANT FILTERS
The backwash operation occurs similar to the filters previously discussed with backwash flow going to the
equalization basins.
RESIDUALS HANDLING SYSTEM
The residuals handling system consists of four basic processes, including backwash equalization, sludge thickening,
sludge dewatering, and decant. As described above, the flow from the backwash operations are piped to an
equalization tank. The residuals are allowed to settle to the bottom of the tank and the clarified water is decanted to
the NPDES discharge in the Yadkin River. Residuals are allowed to accumulate in the bottom of the equalization
tank and periodically removed by pumping and piped to the sludge thickener.
The thickening operation consists of a round, clarifier type thickener. The residuals that are consistently removed
from the sedimentation processes (Super Pulsator and lamella plate) are piped into the sludge thickener where they
are allowed to settle and thicken on the bottom of the tank. The supernatant is decanted from the system and piped to
the NPDES discharge in the Yadkin River. The thickened residuals on the bottom of the tank vary in consistency
from approximately 1.5% to 4% by volume.
The residuals removed from the thickener and piped to a dewatering system that consists of a drum thickener.
Polymer is added to the influent flow. The residuals are thickened to a consistency of approximately 30% by
volume. The residuals are then allowed to continue drying and are stored on a concrete pad adjacent to the
thickening building. The residuals are periodically removed from the site and transported to the landfill for final
disposal. Any decant from the thickening operation is piped back to the clarifier type thickener where it is returned
to the process.

y.z
Water Resources
ENVIRONMENTAL QUALITY
December 05, 2016
Mr. Ron Sink, General Manager
Davidson Water Plant
PO Box 969
Welcome, NC 27374
PAT MCCRORY
Governor
DONALD R. VAN DER VAART
Secretary
S. JAY ZIMMERMAN
Director
Subject: Permit Renewal
Application No. NCO084425
Davidson Water WTP
Davidson County
Dear Mr. Sink:
The Water Quality Permitting Section acknowledges receipt of your permit application and
supporting documentation received on December 1, 2016. The primary reviewer for this renewal
application is Derek Denard.
The primary reviewer will review your application, and he will contact you if additional
information is required to complete your permit renewal. Per G.S. 150B-3 your current permit
does not expire until permit decision on the application is made. Continuation of the current permit
is contingent on timely and sufficient application for renewal of the current permit.
Please respond in a timely manner to requests for additional information necessary to
complete the permit application. If you have any additional questions concerning renewal of the
subject permit, please contact Derek Denard at 919-807-6307 or [e-mail].
Sincerely,
Wren Thedford
Wastewater Branch
cc: Central Files
NPDES
Winston-Salem Regional Office
State of North Carolina I Environmental Quality I Water Resources
1617 Mail Service Center I Raleigh, North Carolina 27699-1617
919-807-6300