NC0088820_Speculative Limits_20090501

NPDES DOCUMENT SCANNING COVER :SHEET
NC0088820
Pender County WTP
NPDES Permit:
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:
May 1, 2009
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MENR
North Carolina Department of Environment and Natural Resources
Division of Water Quality
Beverly Eaves Perdue Coleen H. Sullins Dee Freeman
Governor Director Secretary
May 1, 2009
Mr. Michael G. Mack
Director,PCU
Pender County Utilities
P. O. Box 995
Burgaw, NC 28425
Subject: Speculative Limits for New Pender County WTP
Pender County
Dear Mr. Mack:
You recently requested speculative limits for a proposed new 0.9 MGD wastewater discharge from a
Conventional Water Treatment Plant to be constructed on property owned by Pender County (previously
owned by BSAF), and to discharge to a ditch. We strongly recommend you contact the Wilmington
Regional Office, Surface Water Protection during normal business hours, phone [phone], and
determine what options are available for this discharge regarding receiving streams. You cannot discharge
to a ditch because this is considered a zero flow stream.
Environmental Assessments of New Proiects
Any entity proposing to construct new wastewater treatment facilities using public funds or public
(state) lands must first prepare an environmental assessment (EA). Please contact the Division's State
Environmental Policy Act (SEPA) coordinator, currently Hannah Stallings, at [phone] to determine
the extent of requirements. DWQ will not accept a permit application for a project requiring an
environmental assessment until the Division has approved the EA and sent a Finding of No Significant
Impact (FONSI) to the state Clearinghouse for review and comment.
Engineering Alternatives Analysis (EAA) for NPDES Permit Application
In accordance with the North Carolina General Statutes, the most practicable wastewater treatment
and disposal alternative with the least adverse impact on the environment is required to be implemented
with any new discharge. Therefore, as a component of the NPDES permit application for a new flow, a
detailed engineering alternatives analysis (EAA) .must be prepared. The EAA must justify the requested
flow and provide an analysis of potential wastewater treatment alternatives.
Alternatives to a surface water discharge, such as a spray/drip irrigation, wastewater reuse, or
connection to a Regional WWTP are considered to be environmentally preferable.
Page 1 of 2
1617 Mail Service Center, Raleigh, North Carolina 27699-1617
Location: 512 N. Salsbury St. Raleigh, North Carolina 27604
Phone: [phone] FAX: [phone] Customer Service: 1-877-623-6748
Internet www.ncwaterquality.org
An Equal opportunity Affirmative Action Employer
No Carolina
atura!ly

The permit application for a new flow will be returned as incomplete if all EAA requirements are not
adequately addressed. You can access any information and requirements on the NPDES Unit website,
http://h2o.enr.state.nc.us/NPDES/documents.html.
Speculative Effluent Limits
The speculative limits presented here are based on our understanding of your proposal, applicable
water quality standards, the Division WTP permitting strategy, and present environmental conditions. The
Division of Water Quality (DWQ) cannot guarantee that it will issue a NPDES permit to discharge treated
wastewater into waters of the State. Nor can we guarantee that the effluent limitations and other
requirements included in any permit will be exactly as presented here. Final decisions on these matters
will be made only after the Division evaluates a formal permit application for this discharge, and notices
the proposal for public comment. Tentative limits for the proposed discharge are outlined below.
Speculative Limits for Conventional WTP NPDES discharge to a class C, Sw stream, not impaired, Cape Fear
River Basin (0.9 MGD)
0 F/ow Limit - The flow will be limited to 0.9 MGD as requested. A continuous effluent flow
monitoring/recording device must be maintained and used to document daily discharge events.
Compliance is based on the average of the daily discharge events in any given month.
0 Total Dissolved So/ids (TSS) - The effluent limits for TSS are a maximum 30 mg/L monthly
average and a maximum 45 mg/L daily average. Weekly grab samples are sufficient to determine
the applicable averages.
0 pH - The limit range for pH is not less than 6.0 s.u. nor greater than 9.0 s.u.. Weekly grab
samples are sufficient to determine compliance.
0 Total Residua/ Chlorine (TRC) - Typical conventional treatment process most likely use a
chlorinated based water to backwash and rinse the filter media. The effluent limit for TRC is a
maximum value from 17 µg/L to 28 µg/L depending on the receiving stream flow. TRC compliance
requires measurement of effluent TRC to a minimum of 50 µg/L. If a chlorinated based water is not
used for the filter operation, or is not allowed to enter the effluent, then an effluent TRC limit and
monitoring is not required. Weekly grab sample are sufficient to determine compliance. As part of
the NPDES permit application, the applicant must contact USGS and provide stream flow data for
the receiving stream outfall location, specifically 7Q10 summer and winter flow data.
In addition to these speculative limits the permittee must comply with an effluent toxicity
testing requirement, the effluent monitoring requirements for toxicant parameters, and the effluent
monitoring requirements for nutrient parameters. Effluent grab samples will be sufficient for
determining these testing and monitoring requirements.
If you have any questions about these limits, contact Ron Berry at [phone] or by email at
[e-mail].
Sincerely,
Gil Vinzani, P.P.�ervisor
Eastern NPDES Program
•
cc: Wilmington Regional Office/ Surface Water Protection (email copy)
Central Files
NPDES Files
Page 2 of 2

PENDER COUNTY UTILITIES
605 E. Fremont Street
P.O. Box 995
Burgaw, NC 28425
Phone - 910.259.1570
Fax - 910.259.1579
April 27, 2009
Division of Water Quality
NPDES Unit
1617 Mail Service Center
Raleigh, North Carolina 27699 - 1617
RECEIVED
APR 2 S 2009
DENR - WATER QUALITY
POINT SOURCE BRANCH
Subject: Pender County Surface Water Treatment Plant - Request for Speculative
Effluent Limits
Dear Mr. Vinzani:
We are writing to request preparation of the speculative effluent limits for discharge of up
to 0.9 mgd of process wastewater from the new Pender County Surface Water Treatment
Plant (WTP) to a ditch on the WTP site. Only one discharge location is proposed at this site.
The proposed facility will be located on property already owned by Pender County near the
intersection of Highway 421 and the New Hanover County line (property previously owned
by BASF). The proposed plant and discharge location are shown in the attached figure.
The Pender County Surface Water Supply project consists of construction of a new surface
WTP and related transmission mains from the existing Lower Cape Fear Water and Sewer
Authority (LCFWASA) raw water main (carries Cape Fear River water) to the proposed
WTP site, finished water pumping, and a water transmission system carrying water from
the proposed WTP to the westernmost end of the existing Rocky Point/Topsail Water and
Sewer District along North Carolina NC Highway 210.
The WTP is to be initially sized for 2.2 million -gallon -per -day (mgd) treatment capacity for
about 2.0 mgd net water production (with a bid alternate of 6.0 mgd treatment capacity for
about 5.5 mgd net water production. Net water production is the amount of water treated
minus the amount of water required for plant uses such as filter backwashing.
The recommended treatment process for the Pender County Surface WTP is based on .
conventional treatment. Since the treatment requires up to 10 percent water usage for filter
backwashing, sedimentation solids drainage and other uses, the capacity of the treatment
basins including the filters will be 2.2 mgd with 6.0 mgd bid alternate, so in terms of North
Carolina Public Water Supply plant capacity ratings, the plant will be 2.2 or 6.0 mgd
capacity (sometimes referred to as "filter capacity"). Filter backwashing, sedimentation

Page - 2
April 27, 2009
solids drainage and other uses will amount to up to 0.5 mgd under normal conditions which
requires an NPDES discharge of 0.9 mgd for maximum conditions.
Principal plant features include:
• Raw water main tied to the LCFWASA raw water main
• Rapid mixing
• Tapered energy flocculation
• Conventional sedimentation with chain and ffight solids collection equipment
• Dual media filtration and GAC filtration
• Transfer pump station to pump filtered water to a clearwell
• Finished water pump station
• Finished water transmission main
• Chemical feeders and storage
• Reclamation basins for solids handling
• Decant/Recycle pump station
Thank you for your consideration of our request.
Y truly yo
Michael G. Mack
Director, PCU
cc: Bill Dowbiggin, CDM

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