NC0026921_Technical Assistance Visit_19990827

`DAMES B. HUNT JR
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NORTH CAROLINA DEPARTMENT OFlG--
ENVIRONMENT AND NATURAL RESOURCES
August 27, 1999
Mayor Tim Parnell
Town of Parkton
P.O. Box 55
Parkton, North Carolina 28371
Subject: Technical Assistance Visit
Parkton WWTP
NPDES Permit No. NC0026921
Robeson County
Dear Mr. Parnell:
DIVISION OF WATER QUALITY
FiEc
VPD
EP 7 1999
FFYE T TEVILLE
REG. OFFI67E
A technical assistance visitation was conducted at the Parkton Wastewater Treatment
Plant on August 18, 1999. The primary focus of the visit was to identify operational
and design problems that could contribute to the facility's noncompliance with the
NPDES permit and to suggest possible corrective actions. As a result of the visit, the
7- following comments and/or recommendations are offered:
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,:ter ;.
The main problem associated with this facility seems to be inflow and infiltration
(I&I). I&I can cause a number of problems within a treatment facility. High flows
during rain events can cause solids washout, ineffective disinfection, hydraulic
overloading of treatment units, shorter treatment detention times, and excessive grit
accumulation to name a few. It is this office's recommendation to begin an intense
I&I removal program. Anevaluation of the entire system should be performed.
Smoke testing will determine areas of concern- and then these areas should be
prioritized and work should be concentrated on high priority areas. Past
experiences have shown that during the identification procedure, some systems find
a couple of major areas where high I&I enters the collection system. By correcting
these sources the Town can greatly reduce the amount of I&I to the treatment
system until additional funds can be obtained to work on the more expensive areas.
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2. During my visit I spoke with Mr. Green concerning the comments made by the Fayetteville
Regional Office in a letter dated July 09, 1999. Mr. Green informed me that all the issues
addressed in the July 09, 1999 letter by the region had been addressed. The chlorine contact
chamber should be cleaned on a routine basis; this will prevent solid build-up and help in the
disinfection process. It is my understanding that a flow paced chlorinating system has been
ordered and will be installed very soon. This flow pace system will indeed help prevent fecal
violation during sudden changes in the flow. Both oxidation ditches had been cleaned of solids
when I arrived and it was apparent that during this cleaning process a lot of mixed liquor
suspended solids (MLSS) were lost to the drying beds. The Mixed liquor suspended solids were
extremely low in ditch number 2 and very little treatment _was taking place. I suggested to Mr.
Green that either the ditches be seeded from another wastewater treatment plant or some of the
solids from ditch 1 be moved to ditch 2 so that some treatment could take place. With the ditches
being only 4.5 feet deep, hydraulic overloading from high influent flows should be an important
concern. The ditches should be kept clean of sand accumulation. This accumulation of sand
greatly reduces the detention time in the ditches and thus greatly hinders the treatment process
abilities. It is recommended that the Town's engineer look into the possibility of a grit removal
system being installed at the treatment plant. This removal system would prevent grit and sand
from filling the treatment basins and wearing out the equipment. This grit removal system should
not be considered an alternate solution for controlling the I&I problem.
3. It is recommended that additional process control analyses be run on a routine basis. Process
control data can be very helpful to an operator in determining plant changes and unusual situations
within the process. Mixed liquor suspended solids, centrifuges, settleometers, pH, temperature,
and dissolved oxygen should be analyzed on a regular schedule. This data some be recorded in
detail, so it can be referred to in the future when needed. It was noted that the lab has a fair
amount of lab equipment that was not being used. It is suggested that this lab equipment be
checked. If the equipment is operational, it should be used to help offset contract lab costs for
process analyses.
4. Lastly, I recommend that the digester be put back into service. This unit is not being used at
this time. The tank and piping should be evaluated since it has not been used in some time.
Although the digester is small, sludge could be wasted to the digester and thickened before wasting
to the drying beds. The plant's drying beds should be kept clean of grass and properly dried sludge
should be removed in a timely manner. A possible second use for this digester would be a buffer
until the I&I problem can be corrected. The operator could waste to the digester before heavy rain
events to reduce the MLSS in the oxidation ditches, which would prevent the clarifiers from being
overloaded and having possible solids loss out the effluent. After the plant flow has returned to
normal, solids in the digester could be pumped back to the ditches so the treatment process could
quickly improve. This procedure would require the operator to monitor the situation very closely
and run a low MLSS in the oxidation ditches.

The observations outlined above are those that were the most apparent in contributing to the plant's
noncompliance. It is hoped that these observations and recommendations will assist you in
operating your wastewater facility. Please call me, at (919)-733-0026 ext. 315, to schedule a
follow-up visit or if you should have any questions or need additional information.
Ton Arnold, WWTP Consultant
Tec nical Assistance and Certification Unit
cc: Fayetteville Regional Office
Central Files
TAC Files