NC0056863_Correspondence_20130214

ROSE HILL
Incorporated 1875
TOWN OF ' ROSE HILL
Noi m Cutou t
Home of the World's Largest Frying Pan
Mr. Dean Hunkele
Surface Water Protection Section
NCDENR
127 Cardinal Drive Extension
Wilmington, NC 28508
Subject: NPDES Special Condition
Permit No. NC0056863
Rose Hill WWTP
Duplin County
Dear Mr. Hunkele:
Per Section A.(4). Solids Depth Survey and Removal Plan in the current permit, we
have secured the professional services of a surveyor to perform a gridded solids depth
survey in the oxidation ditch. The survey was conducted on a 25-foot grid cross section
of the oxidation ditch.
The total volume of the treated water (high water level verses the bottom) was
calculated and compared to the total accumulated grit and solids discovered by a
survey on the bottom and sides of the ditch. The majority of the settling of solids is at
the point where the influent is introduced into the ditch at the first paddle wheel. As
noted on the plans, the total storage of the oxidation ditch is 2,089 cubic yards and the
accumulated sludge is 152 cubic yards. Therefore, 93% of the oxidation ditch is being
used to circulate and maintain the adequate treatment process.
To date, the ORC has never seen any evidence of eddying of solid buildups during high
or low flows. He has also been successfully in maintaining the allowable dissolved
oxygen levels and PH. The plant has been in operation since 1983 and we feel that this
discovery of minimum solids buildup is evident of adequate mixing and scouring.
Please contact me should you have any questions concerning this, and we look forward
for your response on these findings.
Sincerely,
Bobby Cavenaugh
Rose Hill Public Utilities Director
Town of Rose Hill
NCPDES: NC0056863
rEIVE.0
FEB 2013
BY:_ _-----
Post Office Box 8, Rose Hill, North Carolina 28458
Telephone [phone] • Fax [phone]
Email: [e-mail] • website: www.rosehill-nc.org/

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