9230_GreenwayWasteApexCDLF_DesignHydroPhase3Approval_DIN 25841_20160329.pdf

PAT MCCRORY
Governor
DONALD R. VAN DER VAART
Secretary

MICHAEL SCOTT
Acting Director

March 29, 2016

Mr. Edward Stephens PG, Project Manager
Civil & Environmental Consultants, INc.
1900 Center Park Dr, Suite A
Charlotte, NC 28217

Re: Design Hydrogeological Data Review
Proposed Phase 3 Expansion
Highway 55 CDLF (SW Permit 9230-CDLF)
DIN 25841

Dear Mr. Stephens,

The Solid Waste Section (Section) has conducted the technical review of the design
hydrogeological data presented by Civil & Environmental Consultants, Inc. (DEC) for the
Greenway Waste Solutions of Apex, LLC (GWS) Highway 55 C &D landfill in Apex NC. The data
report was submitted to the Section by CEC on February 24, 2016 and included an evaluation
estimate of the seasonal high groundwater level (SHGW) and top of bedrock elevations for the
design elements of the proposed Phase 3 expansion area. In addition, CEC proposed that
hydrogeological design data approved by the Section for previous phases are sufficiently
applicable for meeting the design criteria for Phase 3 as well. This includes approved
hydrogeological design data presented for Phase 1 (Construction Plan Application approved
8/12/2002, DIN 20750) and for Phase 2 (Construction Plan Application, February 2009, DIN
5930).

Seasonal High Groundwater & Bedrock Surface Data Evaluation
CEC provided an evaluation the 2009 SHGW potentiometric map data along with water level
data collected between 2009 and 2015 from existing detection monitoring wells for the
facility. Based on CEC’s evaluation of observed and calculated water levels, CEC provided an
estimate of expected SHGW levels for the proposed Phase 3 expansion area, as depicted in
the potentiometric map (Figure 1) and Cross-section A-A’ (Figure 3 in the evaluation
submittal).

Top-of-bedrock and auger refusal data from previous site suitability borings and design hydro
borings and detection monitoring wells for the site were used to determine bedrock surface
elevations in the Phase 3 expansion area. Borings within the footprint of Phase 3 provided
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sufficient areal coverage to meet the design requirements. The bedrock surface map (Figure
1) and Cross-section A-A’ (Figure 3) illustrate the expected bedrock surface elevations for the
Phase 3 area.

Upon review of the CEC evaluation, the Section is in agreement with the findings and
conclusions presented for the seasonal high groundwater levels and the bedrock surface
elevations. In addition, the Section agrees that all previously approved hydrogeologic design
data for the site provides sufficient data to meet all the requirements for design hydrogeologic
report {13B .0538(b)} for the proposed Phase 3 expansion. This data is approved for use in the
engineering design of the Phase 3 expansion.

Prior to construction of cell(s), all piezometers, ground‐water monitoring wells, and borings,
located in the proposed cell(s), shall be properly abandoned by over drilling first (exception for
non‐cased borings) and sealed with grout in accordance with 15A NCAC 2C .0113, entitled
“Abandonment of Wells”.

a. In areas where soil is to be undercut, abandoned piezometers, monitoring wells, and
borings must not be grouted to pre‐grade land surface, but to the proposed base
grade surface to prevent having to cut excess grout and potentially damaging the
wells.

b. Well abandonment records (GW‐30 form) for each decommissioned piezometer, boring, and
groundwater monitoring well must be certified by a Licensed Geologist in accordance with rule
.1623(b)(2)(1) and submitted to the Solid Waste Section in accordance with 15A NCAC
02C.0114(b).

NOTE: Final Geologic, Ground Water and Monitoring Requirements will be included in the
Permit to Construct.

If you have any questions concerning this design hydro approval, please do not hesitate to
contact me via email [e-mail] or phone [phone].

Sincerely,

Perry Sugg, PG
Permitting Hydrogeologist
Solid Waste Section

Cc: Mike Griffin, Greenway Waste Solutions
Scott Brown, PE – CEC Inc
Ed Mussler, P.E. – SWS, Permitting Branch Head
John Murray – SWS, Permitting Engineer