Current through Register Vol. 38, No. 18, March 15, 2024
(a) Site Hydrogeologic Report. In accordance
with Rule .0536(c)(3) of this Section, a permit applicant shall conduct a
hydrogeologic investigation and prepare a report. An investigation shall assess
the geologic and hydrogeologic characteristics of the parcel on which the
C&DLF unit is proposed to be constructed (hereinafter "site") to determine
the suitability of the site for solid waste management activities, which areas
of the site are most suitable for C&DLF units, and the general groundwater
flow paths and rates for the uppermost aquifer. The report shall provide an
understanding of the relationship of the site groundwater flow regime to local
and regional hydrogeologic features with special emphasis on the relationship
of C&DLF units to groundwater receptors such as drinking water wells and to
groundwater discharge features. Additionally, the scope of the investigation
shall include the general geologic information necessary to address compliance
with the location restrictions described in Rule .0536(c)(4) through (c)(10) of
this Section. The site hydrogeologic report shall provide the following
information:
(1) A report on the geology and
hydrogeology of the regional and local study areas as defined in Rule
.1618(c)(1) and (2) of this Subchapter based on research of available
literature for the area. This information is to be used in planning the field
investigation. For sites located in piedmont or mountain regions, this report
shall include an evaluation of structurally controlled features identified on a
topographic map of the area.
(2) A
report on field observations of the site that includes information on the
following:
(A) topographic setting, springs,
streams, drainage features, existing or abandoned wells, rock outcrops
including trends in strike and dip, and other features that may affect site
suitability or the ability to effectively monitor the site; and
(B) groundwater discharge features. For a
proposed site where the owner or operator does not control the property from
any landfill unit boundary to the controlling, downgradient, groundwater
discharge features additional borings, geophysical surveys, or other
hydrogeological investigations shall be required to characterize the nature and
extent of groundwater flow; and
(C)
the hydrogeological properties of the bedrock, if the water table of the
uppermost aquifer is in the bedrock. For the purpose of this Rule, "bedrock"
means material below auger refusal.
(3) Borings for which the numbers, locations,
and depths provide an understanding of the subsurface conditions and
groundwater flow regime of the uppermost aquifer at the site. The number and
depths of borings required shall depend on the hydrogeologic characteristics of
the site. There shall be no less than an average of one boring for each 10
acres of the proposed landfill facility. All borings intersecting the water
table shall be converted to piezometers or monitoring wells in accordance with
15A NCAC
02C .0108. Boring logs, field logs and notes,
and well construction records for all onsite borings, wells, and piezometers
shall be placed in the operating record, and shall also be provided to the
Division upon request. Field logs and notes shall be legible; and may be
typewritten.
(4) A testing program
for the borings that describes the frequency, distribution, and type of samples
taken and the methods of analysis, such as ASTM Standards provided at
https://www.astm.org, used to obtain
the following information:
(A) standard
penetration - resistance using a method such as ASTM D 1586;
(B) particle size analysis using a method
such as ASTM D 6913;
(C) soil
classification: Unified Soil Classification System using a method such as ASTM
D 2487;
(D) formation descriptions;
and
(E) saturated hydraulic
conductivity, porosity, and effective porosity for each lithologic unit of the
uppermost aquifer including the vadose zone.
(5) In addition to borings, other
investigation techniques may be used to obtain an understanding of the
subsurface conditions at the site, including geophysical well logs, surface
geophysical surveys, and tracer studies.
(6) Stratigraphic cross-sections identifying
hydrogeologic and lithologic units, and stabilized water table
elevations.
(7) Water table
information, including:
(A) tabulations of
water table elevations measured at the time of boring, 24 hours, and stabilized
readings for all borings, measured within a period of time short enough to
avoid temporal variations in groundwater flow which could preclude accurate
determination of groundwater flow direction and rate;
(B) tabulations of stabilized water table
elevations over time to develop an understanding of seasonal fluctuations in
the water table;
(C) an estimation
of the long-term seasonal high groundwater table based on stabilized water
table readings, hydrographs of wells in the area, precipitation and other
meteorological data, streamflow measurements from the site frequent enough to
demonstrate infiltration and runoff characteristics, and any other information
available; and
(D) a discussion of
any natural or man-made activities that have the potential for causing water
table fluctuations, including tidal variations, river stage changes, flood pool
changes of reservoirs, high volume production wells, and injection
wells.
(8) The
horizontal and vertical dimensions of groundwater flow including flow
directions, rates, and gradients.
(9) Groundwater contour map(s) to show the
occurrence and direction of groundwater flow in the uppermost aquifer and any
other aquifers identified in the hydrogeologic investigation. The groundwater
contours shall be superimposed on a topographic map. The location of all
borings and rock cores and the water table elevations or potentiometric data at
each location used to generate the groundwater contours shall be shown on the
groundwater contour map(s).
(10) A
topographic map of the site locating soil borings with accurate horizontal and
vertical control, which are tied to a permanent onsite benchmark.
(11) Information for public potable wells and
public water supply surface water intakes within the site characterization
study area in accordance with Rule .0536(c)(1) of this Section, including:
(A) available information and records for
well construction, number and location served by wells, and production rates
for public potable water wells; and
(B) available information for all surface
water intakes, including location, use, and production rate.
(12) Identification of other
geologic and hydrologic considerations including slopes, streams, springs,
gullies, trenches, solution features, karst terranes, sinkholes, dikes, sills,
faults, mines, groundwater discharge features, and groundwater recharge and
discharge areas.
(13) A report
summarizing the geological and hydrogeological evaluation of the site that
includes the following:
(A) a description of
the relationship between the uppermost aquifer of the site to local and
regional geologic and hydrogeologic features;
(B) a discussion of the groundwater flow
regime of the site focusing on the relationship of C&DLF units to
groundwater receptors and to groundwater discharge features;
(C) a discussion of the overall suitability
of the proposed site for solid waste management activities and which areas of
the site are most suitable for C&DLF units; and
(D) a discussion of the groundwater flow
regime of the uppermost aquifer at the site and the ability to monitor the
C&DLF units to ensure early detection of any release of monitored
constituents to the uppermost aquifer.
(b) Design Hydrogeologic Report. A geological
and hydrogeological report shall be submitted in the application for a permit
to construct in accordance with Rule .0535(a)(1) of this Section, and shall
meet the following criteria.
(1) The number
and depths of borings required to characterize the geologic and hydrogeologic
conditions of the site shall be based on the site-specific geologic and
hydrogeologic characteristics of the site, and there shall be no less than an
average of one boring for each acre of the area of investigation. The area of
investigation shall be the area within the C&DLF unit footprint and the
C&DLF unit relevant point of compliance, as defined in Rule .0544(b)(1)(B)
of this Section. The scope and purpose of the investigation shall be as
follows:
(A) The investigation shall provide
information to demonstrate compliance with the vertical separation and
foundation standards set forth in Rule .0540(2) and (5) of this
Section.
(B) The investigation
shall provide detailed and localized data of the hydrogeologic characteristics
of the uppermost aquifer for the proposed phase of C&DLF development and
any leachate management systems to design an effective water quality monitoring
system.
(2) The Design
Hydrogeologic Report shall provide the following information:
(A) the information required in Subparagraphs
(a)(4) through (a)(12) of this Rule;
(B) any technical information that is
necessary to determine the design of the monitoring system as required by Rule
.0544(b) of this Section;
(C) any
technical information that is necessary to determine the relevant point of
compliance as required by Rule .0544(b)(1)(B) of this Section;
(D) for sites located in the piedmont or
mountain regions, rock cores of no less than the upper 10 feet of the bedrock
to provide an understanding of the fractured bedrock conditions and groundwater
flow characteristics of the area of investigation. Testing for the rock corings
shall provide rock types, recovery values, rock quality designation (RQD)
values, saturated hydraulic conductivity and secondary porosity values, and
rock descriptions, including fracturing and jointing patterns;
(E) a groundwater contour map based on the
estimated long-term seasonal high groundwater table that is superimposed on a
topographic map and includes the location of all borings and rock cores and the
water table elevations or potentiometric data at each location used to generate
the groundwater contours;
(F) for
sites located in piedmont or mountain regions, a bedrock contour map
illustrating the contours of the upper surface of the bedrock that is
superimposed on a topographic map and includes the location of all borings and
rock cores and the top of rock elevations used to generate the upper surface of
bedrock contours;
(G) a
three-dimensional groundwater flow net or several hydrogeologic cross-sections
that characterize the vertical groundwater flow regime for this area;
(H) a report on the groundwater flow regime
for the area including groundwater flow paths for both horizontal and vertical
components of groundwater flow, horizontal and vertical gradients, flow rates,
and groundwater recharge and discharge areas;
(I) a report on the soils in the four feet
immediately underlying the waste with relationship to properties of the soil.
Soil testing cited in Subparagraph (a)(4) of this Rule shall be used as a basis
for this discussion; and
(J) if
required by G.S. 89E, a certification by a licensed geologist that all borings
that intersect the water table at the site have been constructed and maintained
as permanent monitoring wells in accordance with
15A NCAC
02C .0108, or that the borings and temporary
piezometers will be abandoned prior to landfill construction in accordance with
the procedures for permanent abandonment of wells as delineated in
15A NCAC
02C .0113, except that at the time of
abandonment, all piezometers within the C&DLF unit footprint area shall be
overdrilled to the full depth of the boring or to the top of bedrock, whichever
is encountered first, prior to grout placement. The level of the grout within
the boring shall not exceed in height the elevation of the proposed base
grade.