WQCS00060_NOV-2019-DV-0318 Response_20190821

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DEPARTMENT OF PUBLIC UTILITIES
POST OFFICE BOX 2263
SMITHFIELD, N.C. 27577
[phone]
August 21, 2019
Mr. Rick Bolich
Raleigh Regional Office
NCDEQ DWR
1628 Mail Service Center
Raleigh, NC 27699-1628
Re: Response to NOV-2019-DV-0318
Permit No. WQC500060 - Johnston County Collection System
Dear Mr. Bolich:
NC Dept OfFnvironmental Quality
AUIG 21 2919
Ralcigh RcgionaI Office
In response to incident number 201901093 (101 NC Hwy 210, Smithfield), Johnston County offer the
following information:
• The spill was caused by an air release valve (ARV) saddle failure, which appeared to be due to
corrosion from contact with the concrete cradle in the base of the manhole. See attached detail
from the original construction drawings.
• The failed ARV is located on a 20" force main that receives flow from eight wastewater pump
stations. A portion of the wastewater flow from the eight wastewater pump stations was
diverted into the existing parallel 12" force main, pumper trucks were used to pump and haul
wastewater at several stations and the equalization basin and old aeration basin at Grifols were
used to hold effluent flow while the force main was shut -down to complete the repair. In
addition, some flow from Grifols was diverted into the Town of Clayton wastewater collection
system while the 20" force main was shut -down for repair. The County utilized all means
necessary in order to minimize the initial SSO and prevent additional potential SSOs while the
20" force main was shut -down for the repair.
• The repair required removal of the concrete cradle that was originally poured with the initial
ARV manhole installation. Once the concrete cradle was removed, a stone base was installed
under the force main, the saddle was replaced and ARV re -installed. In addition to County staff,
the County had two contractors on -site to assist with the repair.
• The spill occurred for approximately 5 hours.
• The County utilized a gas powered sewer pump to divert flow from the failed ARV into a nearby
Town of Smithfield manhole, in order to drain the line to make the repair and to minimize the
initial SSO, while the line was being shut -down and tributary wastewater pump stations were
diverted or shut -down for pump and haul.
• All necessary material, personnel and equipment were available for clean-up and to repair the
ARV. At the SSO site, County staff vacuumed the sewer overflow from the spill area and lightly
limed the area.
• The County is working with a contractor to design and install a retrofit on all existing ARVs along
this force main, in order to prevent additional future saddle failures. Furthermore, the ARVs are
Printed on recycled paper

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Mr. Bolich
August 21, 2019
being routinely monitored and inspected until the retrofit is installed for the ARVs on this force
main.
In addition, we have prepared our department to respond quickly to pipe and appurtenance failures by
maintaining an in-house supply of repair materials for all pipe sizes and implementing a detailed
protocol for emergency response. Furthermore, the County maintains a close working relationship with
several local contractors who provide emergency response repairs, as needed. Johnston County works
aggressively to prevent sanitary sewer overflows and help protect the waters of our area. Please
contact me at [phone] or chandra.farmer@ioh,nstonnc.com if you have any questions or need
additional information regarding this issue.
Sincerely,
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Chandra C. Farmer, PE
Director of Utilities
cc: Rick J. Hester, County Manager
Eric Narron
Mitchell Hayes, Raleigh Regional Office

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FLEXIBLE SEAL
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MIN, 10 LF FORCE MAIN
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CENTERED ON MANHOLE
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NOTES:
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1. FORCE MAIN PIPE SHALL BE
CENTERED ACROSS MANHOLE.
2. CONTRACTOR TO INSTALL
FORCE MAIN AT DEPTH
REQUIRED TO FACILITATE
INSTALLATION OF AIR
RELEASE MANHOLE AT HIGH
POINT OF LINE.
3. SEE PLANS FOR FORCE MAIN
MATERIAL.
4. WHERE DUC nLE IRON PIPE IS
SHOWN ON THE PLANS,
DELETE THE CONCRETE BASE
AND COAT THE OUTSIDE OF
THE PIPE THE SAME AS THE
INSIDE OF THE MANHOLE.
5' DIA. PRECAST
CONCRETE MANHOLE
WITH FLAT TOP
ONC ETE MANHOLE
WITH FLAT TOP
2,000 PSI CONCRETE
BINATION AIR/VACUUM
AIR RELEASE VALVE
2" 0 DRAIN HOLE IN CONCRETE
(SLOPE FLOOR TO DRAIN) (TYP OF 2)
LOCKABLE 24' RING do COVER NCDOT
TRAFFIC RATED W/ 1" DRILLED VENT HOLE
USE STAINLESS STEEL HEXHEAO BOLTS
FLUSH WITH FINISHED GRADE
12" MIN. MANHOLE STEPS SHALL BE
PLACED 16" O.C. WHEN
5' MIN, DEPTH OF MANHOLE EXCEEDS V.
1 BACK FLUSH ATTACHMENT
WITH QUICK COUPLER
24" MAX.
1 /2 PIPE DIA,
APPLY LUBRICANT TO
EXTERIOR OF PVC PIPE
TO PREVENT BOND
TAPPING SADDLE
2" COMBINATION AIR/VACUUM AND
AIR RELEASE VALVE
2" ISOLATION VALVE At
.` _ r6-SCH
INLET PIPING SHALL BE
'''4 40 SS 316
INSIDE OF ARV
MANHOLE SHALL BE FACTORY
EPDXY COATED MIN. 50 MIL MIN 12" #57 STONE
SURFACE DRY. EPDXY SEALER ON2,000 P51 CONCRETEPRIME COATING AND FINISHCOATING SHALL BE 2" !�!EClnl
AIN HOLE
NSP 100 AND NSP 120. (rfP OF 2)
COMBINATION AIR/VACUUM AND AIR RELEASE
MANHOLE FOR FORCE MAIN
NOT TO SCALE ADDENDUM NO. 1
PAGE
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