HomeMy WebLinkAboutWS-2467_3510_CA_LTRRPT_20220425_MMPE_LtrReportWithersRavenel
Our People. Your Success.
115 MacKenan Drive | Cary, NC 27511
t: 919.469.3340 | f: 919.467.6008 | www.withersravenel.com | License No. C‐0832
Cary | Greensboro | Pittsboro | Raleigh | Wilmington
April 25, 2022
State of North Carolina
Department of Environmental Quality
Federal & State Lead Program
Division of Waste Management‐Underground Storage Tank Section
1646 Mail Service Center
Raleigh, North Carolina 27699‐1646
Attn: Mr. Mark Petermann
RE: LETTER REPORT – Sparge Enhanced MMPE Event
Needham Service Station
719 East Main Street
Pilot Mountain, Surry County, North Carolina
Groundwater Incident Number: 3510
UST Number: WS-2467
WR Project Number: 02172214.50
Mr. Petermann:
WithersRavenel, Inc. (WR) has completed an air sparge‐enhanced (ASE) mobile, multi‐phase
extraction (MMPE) event as described in our proposal number TA‐03 for the above referenced
site, approved by the UST Section on January 20, 2022. Activities completed in association with
this TA are discussed in the following paragraphs.
Sparge‐Enhanced MMPE Event
WR personnel, along with Eastern Environmental Management, LLC (EEM) mobilized to the site
on March 21, 2022 for the purposes of performing a 96‐hour ASE‐MMPE event. This event was
initiated to recover light, non‐aqueous phase liquid (LNAPL) or “free product” from monitoring
well MW‐13 (if present) and reduce dissolved‐phase contaminant concentrations in MW‐13,
MW‐2 and MW‐14 on the property. In the performance of the event, EEM utilized air sparge
and vacuum extraction equipment mounted within an enclosed trailer and a 6,000‐gallon (gal)
tanker trailer for storage of recovered fluids.
On arrival, WR personnel opened and gauged monitoring wells MW‐2, MW‐13, MW‐14 and SVE
wells SVE‐1, SVE‐2 and SVE‐3 with a decontaminated product/water interface probe. Gauging
of these wells showed the following:
Well ID Depth to
LNAPL/Product Depth to Water Well Depth LNAPL/Product
Thickness
MW‐2 ---38.97 54.5 ---
MW‐13 ---34.72 46 ---
MW‐14 ---38.26 46 ---
SVE‐1 ---DRY 45 ---
SVE‐2 ---38.56 45 ---
SVE‐3 ---37.93 45 ---
[All measurements shown in feet (ft)]
WithersRavenel
Our People. Your Success.
Needham Service Station Incident #3510 WR Project No. 02172214.50
Letter Report – MMPE Event April 2022
Page 2
Following gauging, the ASE‐MMPE was set up to extract total fluids from wells MW‐2, MW‐13
and MW‐14, while introducing air into well SVE‐1. For completion of ASE‐MMPE activities,
EEM installed 1‐inch (in) diameter (dia) poly‐vinyl chloride (PVC) stingers in the wells, extending
to depths approximately 40‐ft beneath each well’s top of casing. These stingers were plumbed
at surface to 1‐1/2‐in dia chemical resistant flexible hose, which was connected to a vacuum
trunk servicing the vacuum/pressure regenerative blower housed in the equipment trailer.
Following setup, the ASE‐MMPE system was started and run continuously for a period of 96‐
hours to recover total fluids, including LNAPL/free product and contaminated groundwater.
During this time, EEM also operated a 410 cubic foot per minute (CFM) blower to direct air
through a ½‐in air line fitted to SVE‐1 with an air‐tight coupler on the sparge well casing.
EEM personnel monitored the performance of the ASE‐MMPE system over the course of the
event, adjusted the stinger depths and optimized recovery as necessary. Through the course of
the MMPE event, a combined total of 14,289‐gal of fluids were recovered from MW‐2, MW‐13
and MW‐14. Of these fluids, 53.64‐gal were listed as LNAPL. These materials were transported
from the location by EEM and were disposed of at their treatment facility located in Rocky
Mount, NC. Recovery included the emission of 254.33‐gal of LNAPL/free product. The
manifest and disposal document associated with disposal are included as attachments.
After completion of the ASE‐MMPE event, EEM dismantled the setup at the location. WR
personnel gauged the wells with the interface probe during water recovery after removal of the
stingers and did not detect measurable LNAPL/free product following the ASE‐MMPE event.
Field notes and site photos for the March 2022 ASE‐MMPE event are included as Attachment A
while EEM documentation associated with the event are provided as Attachment B.
WR appreciates the opportunity to be of service to the Federal & State Lead Program. Should
you have any questions regarding the attached, please do not hesitate to contact Matt James at
(919) 469‐3340.
Cordially,
WithersRavenel
Kevin B. Buchanan
Staff Environmental Scientist III
Enclosure(s):
ATACHMENT A
FIELD NOTES
SITE PHOTOGRAPHS
PHOTOGRAPH 1
SITE VIEWED TO NORTHWEST
PHOTOGRAPH 2
SITE VIEWED TO WEST‐SOUTHWEST
PHOTOGRAPH 3
MW‐2
PHOTOGRAPH 4
MW‐13
PHOTOGRAPH 5
MW‐14
PHOTOGRAPH 6
MMPE IN OPERATION
PHOTOGRAPH 7
MMPE IN OPERATION
PHOTOGRAPH 8
MMPE IN OPERATION
ATTACHMENT B
MMPE DOCUMENTATION (EEM)