9226_ShotwellCDLF_Phase5WorkPlan_DIN26079_20160425.pdf

1100 Crescent Green Dr., Suite 208, Cary, North Carolina 27529 • O: 919-792-1900 • F: 866-311-7206
April 25, 2016

Ms. Elizabeth Warner
Hydrogeologist
NCDEQ Solid Waste Section, Permitting Branch 217 W Jones St.
Raleigh, NC 27603

Via e-mail

RE: Shotwell C&D Landfill
Phase 5 Expansion
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
Phase 5 Expansion. The purpose of this letter is to document the scope of the Design Hydrogeologic Study
associated with the Permit to Construct Application.

Ten Type II piezometers are proposed for the Design Hydrogeologic Investigation, which encompasses an
approximate 10-acre 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 25 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.

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. Proposed piezometer B-24 will be installed in a locking steel
casing with concrete pad, as it is anticipated that B-24 will become part of the facility Monitoring Plan upon
approval of the Permit to Construct Application. B-24, upon completion, will be designated MW-9. Also,
existing piezometer PZ-2S will be rehabilitated as necessary and retrofit with a locking steel casing with
concrete pad. PZ-2S is anticipated to be incorporated into the facility Monitoring Plan, and will be designated
MW-10.

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.
Ms. Elizabeth Werner
April 25, 2016 Page 2 of 2
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 NX 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-23D and
B-28D.

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 4 expansion. At the conclusion of the design hydrogeologic
study, it is anticipated that piezometer B-24 will be incorporated into the facility Monitoring Plan as MW-9, and
that existing piezometer PZ-2S will be incorporated as MW-10.

Your assistance on this project is greatly appreciated. We look forward to any questions or comments you
may have.

Sincerely,
Garrett and Moore, Inc.

Craig M. Fortner, P.E.

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