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 20.5.119.1900
NMAC. The preliminary investigation shall determine the following, unless
otherwise approved by the department.
A. If not previously identified and reported
under 20.5.119.1903 NMAC, the preliminary investigation shall determine the
source of contamination, 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
hydrocarbon 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 hydrocarbon 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) Owners and
operators shall assess at five-foot intervals, field estimates of
concentrations of petroleum hydrocarbons 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 determinations of 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) Owners and operators shall delimit the
horizontal and vertical extent of contaminant saturated soil as defined in
20.5.101.7 NMAC.
C.
Owners and operators 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 20.5.119.1905 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 20.5.119.1902 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 20.5.119.1902 NMAC;
(ii) checking for the presence of vapors in
accordance with 20.5.119.1902 and 20.5.119.1907 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 20.5.119.1903 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 20.5.119.1902
NMAC;
(b) checking for the presence
of vapors in accordance with 20.5.119.1902 and 20.5.119.1907 NMAC.