9226_ShotwellCDLF_LifeOfSiteDesignHydroWorkPlan_DIN27859_20170601

1100 Crescent Green Dr., Suite 208, Cary, North Carolina 27529 • O: 919-792-1900 • F: 866-311-7206
June 1, 2017
Ms. Elizabeth Werner Hydrogeologist
NCDEQ Solid Waste Section, Permitting Branch 217 W Jones St. Raleigh, NC 27603

Via e-mail

RE: Shotwell C&D Landfill
Life of Site Design Hydrogeologic Study Work Plan

Dear Ms. Werner:
We are in the process of preparing a Permit to Construct Application for the proposed Shotwell C&D
Landfill Life of Site to develop the remaining 19 acres of the approved Facility Plan. The purpose of
this letter is to document the scope of the Design Hydrogeologic Study associated with the Permit to
Construct Application.
Nineteen (19) Type II piezometers are proposed for the Design Hydrogeologic Study, which
encompasses an approximate 19-acre expansion of the disposal footprint. The proposed locations
and designations of the piezometers are shown in Figure 1 (attached). The proposed depths of the
piezometers range from approximately 30 to 55 feet below grade (see Figure 1 for proposed
piezometer depths). At two locations, the piezometers will be installed as shallow and deep pairs.
Concurrent with the piezometer installation, existing piezometers installed within the Phase 5 disposal
footprint will be abandoned by overdrilling and tremie grouting to the ground surface. Existing
piezometers and existing MW-8 scheduled for abandonment are shown on Figure 1. Existing
piezometer PZ-2S will be redeveloped and designated MW-8R.
Prior to initiating field work, North Carolina 811 will be contacted to have underground utilities in the
areas proposed for drilling appropriately marked. All drilling locations will also be approved by the
client prior to drilling.
The proposed Type II piezometers will be installed using a hollow-stem auger drilling rig. All Type II
piezometers will be constructed of 2-inch ID Schedule 40 PVC well casing and 10 feet of machine-
slotted well screen with 0.010” slots. A sand pack will be emplaced within the annular space to
approximately 2 feet above the top of the well screen, above which a 2-foot thick bentonite seal will
be installed. The annular space will be finished with Portland cement/bentonite slurry to grade. The
piezometers will be finished with solid PVC risers extending approximately 2 to 3 feet above grade.
All piezometers will be installed and constructed in accordance with North Carolina Well Standards.
Ms. Elizabeth Werner June 1, 2017 Page 2 of 3
Select piezometers will be incorporated into the facility Monitoring Plan to be submitted with the
forthcoming permit to construct application. The following piezometers are anticipated to become
part of the Monitoring Plan, subject to change based upon encountered subsurface conditions:
B-42
B-44
B-46S
Proposed piezometers that will become part of the Monitoring Plan will be installed in a locking steel
casing with concrete pad.
Soil samples will be collected at each drilling location for lithologic descriptions using the standard
penetration test (SPT) method with a 140-lb sliding hammer and steel split-spoon samplers. Samples
will be collected in 2-feet intervals for every five feet of depth to the completion depth of the boring.
The soil retained in each split-spoon sampler will be logged by a geologist with respect to texture,
composition, color, and moisture content. In addition, one soil sample collected from the saturated
zone at each drilling location will be retained and submitted for grain size analysis at a geotechnical
laboratory to allow for estimating the specific yield of the aquifer sediments. Additional soil index
testing will be performed on select samples to further characterize overburden soils.
Crystalline bedrock samples will be collected using an HX core barrel at boring locations indicated on
Figure 1, attached. Piezometers will be installed within the cored bedrock over depth intervals where
water-yielding fractures are encountered. Based on previous studies performed at the site, it appears
that groundwater is in both the deep overburden and bedrock. Piezometers are to be installed to
assess the degree of hydraulic connection between the bedrock and overburden. Bedrock
piezometers are anticipated in borings B-32D and B-46D.
The augers, drill pipe, core barrel and drill rig will be decontaminated using a pressure washer prior to
and following completion of drilling for the project. Each well will be developed after installation using
a down hole pump or bailer until the discharge water appears to be free of suspended sediments or
for a maximum of one hour.
Each well will be surveyed relative to the existing site datum for horizontal position and elevation by a
North Carolina licensed surveyor. At each well, elevations will be measured of the ground surface
and top of the solid PVC riser. A permanent mark will be made on the top of the PVC riser at the
point where the elevation measurement is made for future reference when collecting depth to water
data.
Approximately three months of groundwater elevation readings will be taken in the newly installed
piezometers and existing monitoring well network for the purpose of confirming and/or adjusting the
seasonal high groundwater table in the vicinity of the Phase 5 expansion.
Your assistance on this project is greatly appreciated. We look forward to any questions or
comments you may have.
Ms. Elizabeth Werner June 1, 2017 Page 3 of 3
Sincerely,
Garrett and Moore, Inc.

Craig M. Fortner, P.E.

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