Current through Register Vol. 35, No. 6, March 26, 2024
Owners and operators shall conduct a preliminary
investigation in accordance with this Subsection and under a timeline approved
by the department or the timeline set forth in Subsection E of 20.5.120.2000
NMAC. The preliminary investigation shall determine the following, unless
otherwise approved by the department.
A. If not previously identified and reported
under 20.5.120.2003 NMAC, the preliminary investigation shall determine the
regulated substance released or suspected of being released at the site, the
media of concern, current and potential receptors, current and anticipated use
of property, complete and incomplete exposure pathways, and routes of
exposure.
B. The preliminary
investigation shall also determine the horizontal and vertical extent and
magnitude of soil contamination.
(1) Owners
and operators shall conduct a soil boring survey by advancing a continuously
cored soil boring at each area of release where soil contamination is most
likely to be encountered unless otherwise directed by the department. The
initial incident report and a soil vapor survey may be used in locating these
areas. Owners and operators shall advance at least one of the borings into the
groundwater saturated zone or, with approval from the department, to a depth at
which measured levels of contaminants in soil are no longer detectable by
laboratory analysis, and vapor concentrations, as determined with a field
instrument, are less than 100 whole instrument units.
(2) Owners and operators shall advance at
least four additional soil borings to characterize the release within property
boundaries. Borings shall be completed to the depth at which contaminants in
soil are no longer detectable by laboratory analysis, and vapor concentrations,
as determined with a field instrument, are less than 100 whole instruments
units. If the soil borings indicate that contaminated soil extends beyond the
boundary of the property on which the storage tank system is located, owners
and operators shall advance soil borings sufficient to characterize the extent
and magnitude of contamination within site boundaries.
(3) The preliminary investigation shall
assess, at five-foot intervals, field estimates of concentrations of
contaminants of concern in the soil borings and select and prepare samples for
laboratory analysis.
(4) Owners and
operators shall gather field data for soil classification, determining and
recording color, grain size, texture, description of lithification, plasticity
and clay content.
(5) The
preliminary investigation shall include derived values for soil bulk density
(g/cc), soil moisture content (percent by mass), and effective porosity, and
fraction organic carbon content (percent by mass) using samples taken from an
uncontaminated area of the vadose zone.
(6) The preliminary investigation shall
delimit the horizontal and vertical extent of contaminant saturated soil as
defined in 20.5.101.7 NMAC.
C. The preliminary investigation shall
determine whether groundwater or surface water has been contaminated above
applicable standards or whether a potential for groundwater or surface water
contamination is present by performing the following:
(1) install at least three groundwater
monitoring wells at locations where the results of the soil boring survey
conducted pursuant to this section indicate that groundwater may be
contaminated; owners and operators shall:
(a)
locate monitoring wells so that groundwater gradient can be
determined;
(b) install at least
one monitoring well on site in the area of highest contamination as determined
by the soil borings installed in conformance with the initial incident report
and other relevant information;
(c)
install one of the monitoring wells in the estimated down-gradient direction
from the area of highest contamination;
(d) construct wells in accordance with all
applicable federal, state and local laws and regulations; and
(e) survey the wells using a New Mexico
licensed professional surveyor, in decimal degrees of latitude and longitude in
accordance with NAD 83;
(2) calculate the direction and gradient of
groundwater flow;
(3) inspect all
monitoring wells for the presence of NAPL using a method approved by the
department; if NAPL is present in any well, measure the apparent thickness,
delimit its horizontal extent, and initiate recovery procedures in accordance
with 20.5.120.2005 NMAC; and
(4)
sample each monitoring well that does not contain NAPL and analyze the sample
for contaminants of concern to determine whether:
(a) immediate mitigation procedures are
warranted; and
(b) other hazardous
conditions exist as a result of the release if not previously identified in
accordance with 20.5.120.2002 NMAC by:
(i)
identifying the location and depth of underground utilities and other
subsurface structures on or adjacent to the site not identified earlier in
accordance with Subsection E of 20.5.120.2002 NMAC;
(ii) checking for the presence of vapors in
accordance with 20.5.120.2002 and 20.5.120.2008 NMAC; and
D. Owners and operators
shall identify all other hazards and potential threats to public health, safety
and welfare and the environment which may exist as a result of the release to
determine if:
(1) immediate mitigation
procedures are warranted; and
(2)
other hazardous conditions exist as a result of the release if not previously
identified in accordance with 20.5.120.2003 NMAC by;
(a) identifying the location and depth of
underground utilities and other subsurface structures on or adjacent to the
site not identified earlier in accordance with Subsection E of 20.5.120.2002
NMAC.
(b) checking for the presence
of vapors in accordance with 20.5.120.2002 and 20.5.120.2008 NMAC.
