NC0023884_Meeting Notes_19931020

InterOffice Memo
To: File
From: Betsy Johnson
Date: October 20, 1993
Subject: Salisbury WWTP meeting with Pierson & Whitman
Pierson and Whitman were called in today to discuss the diffuser design for the proposed Yadkin River
outfall.
Meeting attendees:
Betsy Johnson, Ruth Swanek, Don Safrit, Colleen Sullins
Troy Doby, Mike Aquesta
The diffuser design was discussed. Under the current design the ports will interfere with recreational
boating. The exit velocity is 1 ft/sec. 10 ft/sec is recommened. The consultant will relocate the diffuser
into the river channel and run CORMIX using various scenarios beginning with a single port outfall. The
diffuser will require pumping. We discussed the "bypasses". We may permit them with constraints such
as requiring they notify the region when the diffuser will be off-line.
The Town Creek WWTP (5 MGD) will be pumped to the Yadkin within 3 years. However by then the
flow limit will be exceeded. In order to treat the additional flow, Salisbury may build two additional
clarifiers. If Salisbury can meet the flow limit at the Yadkin (12.5 MGD), is a permit modification
required? No... But, Salisbury plans to add creek water to the effluent line which will run between Town
Creek and the Grants Creek pipe... this flow may cause flows to exceed 12.5 MGD. How much flow from
creek? 2-5 MGD...this is more water than Town Creek contains in the summer. We asked P&W to
rethink the withdrawal...look for other ways to keep the effluent from becoming septic while in the pipe.
There will be chlorination, dechlorination, and post -aeration at the Yadkin outfall site.
P&W is planning to construct a "Kruger" batch reactor WWTP for the Yadkin outfall (20 MGD). This
method has not been used in NC for advanced treatment yet but appears feasible. It includes TP removal
to 0.1 mg/I. The nutrients are removed chemically prior to biological treatment and the supernatant (low
in solids) removed from the plant. More land application may be needed or a thickening process. Don
asked them to come in some time to educate us on this treatment process.
P&W requested that we assign stringent limits for the Grants Creek and Town Creek renewals in order to
help Salisbury with their bond referendum. We will give stringent nutrient limits and notify Salisbury
that expansions at the existing sites will not be permitted without advanced tertiary treatment. The
existing limits do not protect water quality.
CC: 7u.c
Pan
Celeeh.