19039_Oneida Mill_VIMS_20160108

INERAL
PRrNGS
enviranmontaJ. p.c.
.taoo Mineral Springs Lane
Raleigh, NC 27616
January 8, 2016
Mr. Lebeed Kady
North Carolina Brownfields Program
1646 Mail Service Center
Raleigh, North Carolina 27699-1646
Subject:
Dear Mr. Kady
Letter Report for the Proposed Sub Slab Vapor Mitigation System
Oneida Mills/Former Kayser Roth Facility
219 Hardin Street
Graham, North Carolina
MSElob838
Mineral Springs Environmental, (MSE) on behalf of our client, Pumpkin Hill Mill, LLC is pleased
to submit this Letter Report for the Proposed Sub Slab Vapor Mitigation System for the Oneida
Mills Site in Graham, North Carolina. The purpose of this letter is to outline the system design
specifications for the sub slab vapor mitigation system and is respectfully submitted to the
North Carolina Brownfields Program (NCBP) for review and comment. MSE contracted a North
Carolina Professional Engineer to design the system.
Potential sub-slab vapors in the indoor air space will be mitigated by a vapor ventilation system
installed beneath building slabs and within crawl space areas of three buildings at tine site. The
basis for the mitigation design is EPA Document EPA/625/R-92/-016, Radon Prevention in the
Design and Construction of Schools and Other Large Buildings, 1994. Drawings of the proposed
system layout are attached.
The vapor mitigation system will consist of:
1. Ten, two-inch diameter vertical vent extraction wells installed just beneath the building floor
slab within two building footprint areas (defined as "Building 3" and the northern portion of
"Building 2"). The wells will be installed within a 18-20" cored hole in the slab (12"·16"
diameter hole excavated in the sub slab soil), at a depth just beneath the base of the slab,
and will each consist of an open-ended, two inch diameter Schedule 40 PVC pipe. In
location (s) where the well will be installed within a common utility trench beneath the slab,
the end of the pipe will be fitted with a two-inch Schedule 40 PVC tee. The slab
penetrations will be sealed with a liquid boot trowel grade seal or equivalent. The riser
piping will be installed within the interior walls of the buildings, and equipped with an
electric vent fan installed within the interstitial space between the drop ceilings of the
bathroom areas and roof deck within the building interior. The exhaust piping from the fan
will be solid, Schedule 40 PVC pressure piping, four-inch diameter, and connected to the
vertical vent points through fittings and unions installed to remove contaminant vapors
under negative pressure induced by the vent fans. Based on the depth of the extraction
points, size of extraction vent fan and sub-slab soil characteristics, the design radius of
influence of each extraction point is estimated to be 20 feet.
2. A horizontal extraction piping network consisting of a total of approximately 500 feet of two-
inch, Schedule 40 PVC piping that will be installed within the crawl spaces of two building
footprint areas (defined as "Building 4" and the southern portion of "Building 2"). The
piping will be perforated, with '12' diameter weep holes installed at six-inch separation on
each pipe, will be capped at the un-mainfolded ends, and will connect to a total of
approximately 600 feet of three-inch, Schedule 40 PVC pipe manifold through wye
connections. Vapors collected in the horizontal piping will be directed to the exterior
atmosphere through a total of approximately 200 feet of three-inch, Schedule 40 PVC riser
pipe installed within the internal bathroom walls of the building. The riser piping will be
equipped with an electric vent fan installed within the interstitial space between the drop
ceilings of the bathroom areas and roof deck within the building interior. The exhaust
piping from the fan will be solid, Schedule 40 PVC pressure piping, four-inch diameter, and
connected to the vertical vent points through fittings and unions installed to remove
contaminant vapors under negative pressure induced by the vent fans. Based on the length
and layout of horizontal vent piping, size of extraction vent fan and sub-slab soil
characteristics, the design radius of influence of each manifold pipe branch is estimated to
be 20 feet
3. A vapor membrane barrier installed on the concrete floor slab of Building 3 and the northern
portion of the Building 2 slab. The barrier will consist of a 3/8" thick layer of Geo-Seal®
Core (60 mil), overlain by a 3/8" thick layer of Geo-Seal® Base that will be spray or mop-
applied to the existing concrete slab. The barrier will be covered with a 3/4" layer of Gyp-
Crete® Floor Underlayment with 2,000 psi compressive strength, over which will be installed
the finished floor. The barrier will be sealed around the vertical vent riser piping with
overlapping layers of Geo-Seal® Core, Base and Bond, secured around the pipe with cable
ties
4. A vapor membrane barrier installed across the entire crawlspace footprint area of Buildings
2 and 4. The barrier will consist of a 20 mil, polyethylene (PE) or high density polyethylene
(HDPE) liner material (VaporBiock® PlusTM 20 or like). The barrier will be placed over the
horizontal vent piping and manifolds, with about six inches of barrier extending up the walls
of the crawlspace and sealed to the wall with weather-proof tape. Pipe and building footer
penetrations through the barrier will be sealed with a polyurethane seal.
s. Twelve, Fantech® HP 220, and two, HP190 electric radon-type vent fans installed on the
vent pipe risers to induce a vacuum in the piping and remove sub-slab contaminant vapors.
Each fan will be designed at a maximum flow rate of up to 200 CFM at up to 2" of static
head pressure, and operate at 11SV DC power. The fans will be installed at locations ~s
shown on the proposed system layout drawings, and the exhaust stack from each fan will
extend two feet above the roofline of the building. The fans will be spaced a minimum
distance of 10 feet away from air intake ducts on the building roof, per EPA guidelines for
radon ventilation systems. The exhaust piping from each fan will be fitted with a galvanized
steel rain cap to reduce moisture intrusion into the piping. Neoprene boot seal/roof flashing
will be placed at the vent pipe exhaust penetration locations through the roof structure. A
3/8" diameter hole will be drilled through the exhaust piping above the roofline to allow for
flow monitoring and sampling of exhaust vapors, if necessary.
6. MSE proposes to implement the following testing protocol following system installation:
• Smoke testing in the vicinity of all extraction points, pre-building occupancy. The
test will consist of waiving a smoke pen around interior slab penetrations and/or
wall and floor seams at several locations in the buildings to verify sub-slab de-
pressurization, identify any leaks in the concrete slab seal, and evaluate the radius
of influence of the system.
• Indoor air quality testing in the crawl space areas of Buildings 2 and 4 and in
selected interior building locations of all buildings pre-occupancy. The crawl space
and indoor air quality monitoring will consist of the placement of one-liter Summa
canisters with flow regulators in selected locations in the crawl space of Buildings 2
and 4 and interior spaces of Buildings 2, 3 and 4. The canisters will be placed at
floor level to collect samples in the air space just above floor level. Indoor air
quality samples will be obtained from the locations in general accordance with IHSB
guidelines. The samples will be collected over an eight-hour interval and sent to a
laboratory for analyses of VOCs by EPA Method T0-15. Results will be compared to
applicable IHSB and EPA Residential Screening levels to establish baseline VI risk
levels for comparison to post-occupancy levels and evaluate the effectiveness of the
mitigation system.
• Following one year of building occupancy, follow-up sub slab vapor and indoor air
quality monitoring will be conducted at the same locations. Results of the follow-up
sampling will be compared to the pre-occupancy sampling to evaluate mitigation
system effectiveness. Ideally, the pre-and post-occupancy testing will be conducted
during different times of year to evaluate the effect of environmental conditions on
sub slab vapors and indoor air quality.
• Additional testing may include verification of flow within the vent piping through
insertion of a flow meter or manometer probe in the stack test ports upstream of
the fan.
Following the completion of each sampling event, a summary letter of the test results will be
submitted to the NCBP, which will be sealed by a licensed engineer.
Since vapors will be collected from the vadose zone and beneath the building slab, and weep
holes are provided for release of accumulated moisture within the horizontal piping, a moisture
separator to separate liquids from the vapor stream vented from the subsurface will not be
included as part of this system. Emissions from the vapor system are not projected to be more
than five tons per year (based on available sub-slab vapor-phase contaminant data); therefore,
no additional vapor-phase equipment is proposed for the design. Operating noise levels of the
vent fans are expected to be less than 70 dB; therefore, no additional noise dampening
equipment is proposed with the design.
If you should have questions please do not hesitate to contact me at [phone].
Sincerely:
if;:0iJ~s~;rc.
Kirk B. Pollard, L.G.
Principal Geologist
Andy Rodak PE
Professional Engineer
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3" "PVC PIPE
MANIFOLD (BLDG 3 ONLY)
3" "PVC UNION
4" ROOF PENETRATION
AND RUBBER SLEEVE
SEALED FLOOR
PENETRATION
(SEE DETAIL
VENT FAN (RATED FOR EXTERIOR USE)
2' (MAX.)
115 V ELEC (MOUNT ON ROOF JOIST)
4" PIPE HANGER EVERY 10' FROM ROOF
TRUSS (BLDG 3 ONLY)
3" VENT PIPE STUB-UP
(INSTALL WITHIN INTERIOR WALL)
FLEXIBLE COUPLING
4" EXHAUST (RELEASE
ABOVE ROOF-LINE)
2" "PVC VENT PIPE
(INSTALL
WITHIN WALL)
2" "PVC UNION
4" ROOF PENETRATION
AND RUBBER SLEEVE VENT FAN
(RATED FOR EXTERIOR USE)
115 V ELEC
VENT PIPE SLAB
PENETRATION
4" EXHAUST (RELEASE
ABOVE ROOF-LINE)
2" PERFORATED SCH 40 PVC PIPE
20 MIL VAPOR BLOCK PLUS
OR LIKE MEMBRANE
SEAL AROUND WALL, FOOTER, AND PIPE PENETRATION
WITH POLYURETHANE SEAL
EXTERIOR
BLDG WALL
4' BALL VALVE
VENT PIPE PROFILE VIEW
CRAWL SPACE
VENT PIPE PROFILE VIEW
SLAB ON GRADE
3" PVC MANIFOLD
GEO-SEAL
PENETRATION
(SEE DETAIL)
2" PVC PIPE
STUB 6" ABOVE FLOOR SLAB
EXT. FLOOR SLAB
GEO-SEAL BASE
18-20"
VAPOR VENT CONSTRUCTION NOTES
1. INSTALLATION OF THE VAPOR PIPE SHALL INVOLVE SAW-CUTTING A 4" DIAMETER HOLE IN THE FLOOR / CONCRETE SLAB
AND INSERTING THE VENT PIPE TO A DEPTH JUST BENEATH THE BOTTOM OF SLAB GRADE.
2. IF OBSTACLES ARE ENCOUNTERED DURING PIPE INSTALLATION, CONTRACTOR SHALL MAKE ALL REASONABLE ATTEMPTS
TO CARRY THE WORK PAST SUCH OBSTACLES . IF THE CONTRACTOR CANNOT COMPLETE THE INSTALLATION, THE HOLE
SHALL BE ABANDONED AND ANOTHER HOLE SHALL BE MADE WHERE DIRECTED BY THE ON-SITE BUILDING CONTRACTOR.
MATERIAL SPECIFICATIONS
1. WELL CASING: NOMINAL 4" DIAMETER, TYPE I, SCH 40 FLUSH-JOINT THREADED PVC (ASTM -D 1785 OR LATEST REVISION)
2. LIQUID BOOT TROWEL GRADE SEAL OR LIKE SHALL BE POURED AROUND PERIMETER OF HOLE TO JUST ABOVE SLAB GRADE
PER MANUFACTURER'S RECOMMENDATIONS.
TERMINATE VENT PIPE AT BOTTOM OF SLAB
6-8" RADIUS
OPEN HOLE
CAD DATE:
PROJECT NO:
CAD FILE:
REFERENCE:
APPROVAL:
DRAWN BY:
DRAWING NO:
NOT TO SCALE
PROPOSED VAPOR MITIGATION SYSTEM DETAILS
BUILDINGS 2,3,4-CRAWL SPACE AND S-O-G
ONEIDA MILLS
GRAHAM, NORTH CAROLINA
INTERIOR DROP CEILING
(BATHROOM)
SECURE MEMBRANE ON EXTERIOR
WALL, MIN. 6' OVERLAP, WITH
WEATHER-PROOF TAPE OR SEALANT
3/8" VACUUM
TEST/SAMPLE PORT
2' (MAX.)
FLEXIBLE COUPLING
4' BALL VALVE
3/8" VACUUM
TEST/SAMPLE PORT
4" RAIN CAP
4" RAIN CAP
INTERIOR DROP CEILING
(BATHROOM)
2" TEE (IF INSTALLED IN
UTILTY TRENCH)
INSTALL 2" TEE FOR VENT INSTALLATION
EXT. SUB SLAB SOIL
IN UTILITY TRENCH
NOV-2015
RNL
AMR
VENT PENETRATION THROUGH SLAB DETAIL
3/8" THICK GEO-SEAL
CORE (60 MIL)
GEO-SEAL BASE (3/8")
3/4" GYP-CRETE FLOOR
UNDERLAYMENT, 2,000 PSI
GEO-SEAL CORE (30 MIL)
REINFORCEMENT FABRIC
GEO-SEAL CORE (30 MIL)
GEO-SEAL BOND
CABLE TIE