NC0087840_Correspondence_20041203

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Larry Dane( Nayor Pro-?em
December 3, 2004
Mr. Mark McIntire
NPDES Unit— NC DWQ
1617 Mail Service Center
Raleigh, NC 27699-1617
Re: NPDES Permit NC0087840
Backwash Water Discharge
Water Supply Well #4
Dear Mr. McIntire:
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The Town of Middlesex is in receipt of the NPDES Permit for the backwash water discharge
from Water Supply Well #4. There are several provisions in the permit that are of concern to the
Town of Middlesex. The purpose of this letter is bring our concerns to your attention and make
several recommendations which we believe will result in much more appropriate and manageable
permit requirements. Our concerns and recommendations are as follows:
l . The permit calls for monthly monitoring of most parameters. The Town fully expects
that the well will be backwashed only quarterly. Therefore, it would be more appropriate for the
monitoring frequency to be quarterly or whenever the filters are backwashed. There will be no
effluent flow except when the filters are backwashed. Therefore, monthlymonitoring is not
appropriate.
2. It is my understanding that several photos of the well site, the sand filters, and the
roadside ditch into which the backwash water will be discharged, have been sent to you by the
Town's Engineer. As you can tell from those photos, the backwash water discharge point is into
a roadside ditch along Finch Avenue (US Hwy 264 Alternate). The backwash water will pass
through the sand filters prior to discharge to remove solids. The discharge point is more than one
thousand feet uphill from the first culvert under the roadway, over 2,000 feet away from the fast
USGS Quad Sheet blueline stream, and well over 7,000 feet away from Turkey Creek. Please
see attached maps. At the rate of discharge that can be expected from the sand filters, the
effluent water will never get to the above noted first blueline stream. In fact, it is most likely that
the effluent water will never get to the first culvert under the roadway. It will be absorbed into

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252-235-5762 p.2
the ground or it will evaporate before it gets to this point. The effluent water will most certainly
never reach Turkey Creek. Therefore, upstream and downstream sampling requirements on
Turkey Creek are not appropriate. In fact, there are no appropriate locations to take upstream and
downstream wmVles for this discharge. As a means of assuring that the water does not get to
Turkey Creels, the Town will commit to baCkwashing only at dry weather times, that is, not
immediately preceding, during or immediately after arain event.
3. The permit calls for the installation of a holding tank upstream of the sand filters as a
means of slowing down the discharge gate. The Town of Middlesex agrees with the idea of
slowing down the discharge rate. The existing sand filters will do that. However, as a secondary
measure to ensure a slow discharge rate, the Town proposes to install a throttling gate valve on
the sand filter effluent pipe. This gate valve can be throttled to control the discharge rate. The
sand filters can be used as the holding tank. This would be a much more economical means of
slowing the discharge rate and would actually be easier to manage.
4. The Town has investigated the possibility of conveying the backwash water to the
sanitary sewer. A sanitary sewer manhole exists across the street from the well site
approximately 300 feet away. Although it would be possible to pipe the bac"rash water to this
sewer line, the Town ofMiddlesex is prohibited from adding new wastewater into its sanitary
sewer system because it has exceeded its capacity at the Zebulon Wastewater Treatment Plant.
Therefore, this alternative is not curnently available to the Town.
A re-evaluation of the NPDES Permit Monitoring Requirements is requested. Please take these
extenuating circumstances and our above noted concerns and recommendations into
consideration duriig your review. It is important that the Town of Middlesex put the new well
into full operation as soon as possible. The issuance of a NPDES Permit that is better suited to
the actual conditions that exist at the well will allow us to do that. Your timely review of this
request would be greatly appreciated. If you have any questions concerning this matter, please do
not hesitate to call Ms. Peggy Bissette, Town Administrator (252-235-5761), or Dr. Michael S.
Acquesta, PE, the Town's Engineer (919-782-8300).
Sincerely,
Larry Daniel
Mayorpro-Tem

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