NC0025348_Proposal Conceptual Framework_20140515

Aldermen
Dallas O. Blackiston
Victor J. Taylor
Patricia C. Schaible NORTH C A R O L I N A
Johnnie Ray Kinsey 300 Pollock Street, P.O. Box 1129
Bernard W. White
)effreyT. Odham New Bern, NC 28563-1129
[phone]
1111
NEW BERM
June 27, 2014
Mr. Tom Belnick
NC Division of Water Resources
NPDES Complex Permitting Unit
1617 Mail Service Center
Raleigh, NC 27699-1617
FrdpoS�..�
Subject: City of New Bern
Water Reclamation Facility Nitrogen Credit Methodology
Permit No. NC0025348
Mr. Belnick,
Dana E. Outlaw
Mayor
Mark A. Stephens
Interim City Manager
Veronica E. Mattocks
City Clerk
Keith M. Fiaschetti
Director of Finance
In accordance with the City of New Bern's NPDES permit effective December 1,
2013 (NC0025348), please find below the conceptual framework for the proposed subsurface
nitrogen load estimate methodology. This methodology was discussed during a meeting with
representatives of Aquifer Protection Section and Surface Water Protection Section on March
14, 2014 in the Washington Regional Office of DWR.
The City will continue to monitor water levels and sample water quality in the lake
and monitoring wells, as well as sample for nitrogen and other constituents in the effluent
being pumped to the lake. The City will also continue annual algae surveys for the lakes.
This sampling and monitoring will be in accordance the requirements of the NPDES and the
Reclaimed Water/Conjunctive Utilization (WQ0017635) permits.
In order to provide a reasonable estimate of the subsurface total nitrogen loading to
the Neuse River, we will work with a hydrogeologist to develop a suitable groundwater flow
model to estimate flow out of the lake and into the Neuse River, based upon known
subsurface data and past studies on transmissivity of the aquifer. This model, along with
monitored water levels in the lake and surrounding lakes, creeks and wells, should provide a
reasonable indication of subsurface flow for use in a transport model. The transport model
will utilize inputs for nitrogen concentration and effluent flow into the lake to determine mass
loading for a given year, assuming effluent is being pumped to the lake 365 days a year at
maximum concentration. Nitrogen utilization within the quarry and along the river bottom
sediments will be accounted for in the model based on utilization rates from existing,
documented research of these processes. This model will then be utilized to predict the time

Mr. Tom Belnick
Page 2 of 2
required for nitrogen concentrations to reach the Neuse River, under the projected loading.
We will compare this projected annual loading with the actual annual nitrogen loading, and
make adjustments in the credits requested during each permit renewal, as well as updating the
model. We will continually research ways to improve the transport model. as well as
methods to predict/determine nitrogen uptake in the lake and bottom sediment.
We hope this methodology is acceptable to the Division. Should you have any
questions or wish to discuss this request further, please contact our office at your earliest
convenience.
Respectfully,
Jordan B. Hughes. P.E.
City Engineer
Cc: Jay Zimmerman DWQ - Section Chief— Aquifer Protection Section
David May — DWQ — Regional Supervisor — Aquifer Protection Section
Matt Matthews — DWQ — Section Chief— Surface Water Protection Section
Mike Templeton — DWQ — Surface' Water Protection Section
Jon Risgaard — DWQ — Aquifer Protection Section
Blaine Humphrey, P.E. — Rivers & Assoc.
Judy Majstoravich — City of New Bern