South Carolina Code of Regulations › Chapter 61 - DEPARTMENT OF HEALTH AND ENVIRONMENTAL CONTROL › Subchapter 61-58.5 - Maximum Contaminant Levels in Drinking Water › Section 61-58.5.O - VOC Monitoring, Sampling and Analytical Requirements

Current through Register Vol. 48, No. 6, June 28, 2024
(1) This section
			 shall apply to community and non-transient non-community water
			 systems.
(2) Beginning with the
			 initial compliance period analysis of the contaminants listed in Section N(2)
			 above, for the purpose of determining compliance with the maximum contaminant
			 level shall be conducted as follows:
(a)
			 Groundwater systems shall take a minimum of one (1) sample at every entry point
			 to the distribution system which is representative of each well after treatment
			 (hereafter called a sampling point). Each sample must be taken at the same
			 sampling point unless conditions make another sampling point more
			 representative of each source or treatment plant.
(b) Surface water systems (or combined
			 surface/ground) shall take a minimum of one (1) sample at points in the
			 distribution system that are representative of each source or at each entry
			 point to the distribution system after treatment (hereafter called a sampling
			 point). Each sample must be taken at the same sampling point unless conditions
			 make another sampling point more representative of each source, treatment
			 plant, or within the distribution system.
(c) If the system draws water from more than
			 one (1) source and the sources are combined before distribution, the system
			 must sample at an entry point to the distribution system during periods of
			 normal operating conditions (i.e., when water representative of all sources is
			 being used).
(d) Each community and
			 non-transient non-community water system shall take four consecutive quarterly
			 samples for each contaminant listed in Section N(2)(b) through (u) above,
			 during each compliance period beginning in the initial compliance
			 period.
(e) If the initial
			 monitoring for contaminants listed in Section N(2)(a) through (h) and the
			 monitoring for the contaminants listed in Section N(2)(i) through (u) as
			 allowed in paragraph (2)(r) of this section, has been completed by December 31,
			 1992, and the system did not detect any contaminant listed in Section N(2)
			 above, then each ground and surface water system shall take one (1) sample
			 annually beginning with the initial compliance period.
(f) After a minimum of three (3) years of
			 annual sampling, the Department may allow groundwater systems with no previous
			 detection of any contaminant listed in Section N(2) above, to take one (1)
			 sample during each compliance period.
(g) Each community and non-transient
			 non-community ground water system which does not detect a contaminant listed in
			 Section N(2) above, may apply to the Department for a waiver from the
			 requirement of paragraphs (4)(e) and (4)(f) of this section after completing
			 the initial monitoring. (For the purposes of this section, detection is defined
			 as 0.0005 mg/l.) A waiver shall be effective for no more than six (6) years
			 (two compliance periods). The Department may also issue waivers to small
			 systems for the initial round of monitoring for
			 1,2,4-trichlorobenzene.
(h) The
			 Department may grant a waiver after evaluating the following factor(s):
(i) Knowledge of previous use (including
			 transport, storage, or disposal) of the contaminant within the watershed or
			 zone of influence of the system. If a determination by the Department reveals
			 no previous use of the contaminant within the watershed or zone of influence, a
			 waiver may be granted.
(ii) If
			 previous use of the contaminant is unknown or it has been used previously, then
			 the following factors shall be used to determine whether a waiver is granted.
(A) Previous analytical results.
(B) The proximity of the system to a
			 potential point or non-point source of contamination. Point sources include
			 spills and leaks of chemicals at or near a water treatment facility or at
			 manufacturing, distribution, or storage facilities, or from hazardous and
			 municipal waste landfills and other waste handling or treatment
			 facilities.
(C) The environmental
			 persistence and transport of the contaminants.
(D) The number of persons served by the
			 public water system and the proximity of a smaller system to a larger
			 system.
(E) How well the water
			 source is protected against contamination such as whether it is a surface or
			 groundwater system. Groundwater systems must consider factors such as depth of
			 the well, the type of soil, and wellhead protection. Surface water systems must
			 consider watershed protection.
(i) As a condition of the waiver a
			 groundwater system must take one (1) sample at each sampling point during the
			 time the waiver is effective (i.e., one sample during two compliance periods or
			 six years) and update its vulnerability assessment considering the factors
			 listed in paragraph (2)(h) of this section. Based on this vulnerability
			 assessment the Department must reconfirm that the system is non-vulnerable. If
			 the Department does not make this reconfirmation within three (3) years of the
			 initial determination, then the waiver is invalidated and the system is
			 required to sample annually as specified in paragraph (e) of this
			 section.
(j) Each community and
			 non-transient non-community surface water system which does not detect a
			 contaminant listed in Section N(2) above may apply to the Department for a
			 waiver from the requirements of paragraph (4)(e) of this section after
			 completing the initial monitoring. Composite samples from a maximum of five
			 sampling points are allowed, provided that the detection limit of the method
			 used for analysis is less than one-fifth of the MCL. Systems meeting this
			 criteria must be determined by the Department to be non-vulnerable based upon a
			 vulnerability assessment during each compliance period. Each system receiving a
			 waiver shall sample at the frequency specified by the Department (if
			 any).
(k) If a contaminant listed
			 in Section N (2)(b) through (u) above, is detected at a level exceeding 0.0005
			 mg/l in any sample, then:
(l)
			 Systems which violate the requirements of Section N(2) above, as determined by
			 paragraph (2)(o) of this section must monitor quarterly. After a minimum of
			 four (4) consecutive quarterly samples which shows the system is in compliance
			 as specified in paragraph (2)(o) of this section, the system and the Department
			 determines that the system is reliably and consistently below the maximum
			 contaminant level, the system may monitor at the frequency and time specified
			 in paragraph (4)(k)(iii) of this section.
(m) The Department may require a confirmation
			 sample for positive or negative results. If a confirmation sample is required
			 by the Department, the result must be averaged with the first sampling result
			 and the average is used for the compliance determination as specified by
			 paragraph (2)(o) of this section. The Department has the discretion to delete
			 results of obvious sampling errors from this calculation.
(n) The Department may reduce the total
			 number of samples a system must analyze by allowing the use of compositing.
			 Composite samples from a maximum of five sampling points are allowed, provided
			 that the detection limit of the method used for analysis is less than one-fifth
			 of the MCL. Compositing of samples must be done in the laboratory and analyzed
			 within fourteen (14) days of sample collection.
(i) If the concentration in the composite
			 sample is 0.0005 mg/l for any contaminant listed in Section N(2) above, then a
			 follow-up sample must be taken within fourteen (14) days at each sampling point
			 included in the composite, and be analyzed for that contaminant.
(ii) If duplicates of the original sample
			 taken from each sampling point used in the composite are available, the system
			 may use these instead of resampling. The duplicate must be analyzed and the
			 results reported to the Department within fourteen (14) days of
			 collection.
(iii) If the population
			 served by the system is greater than 3,300 persons, then compositing may only
			 be permitted by the State at sampling points within a single system. In systems
			 serving 3,300 persons, the Department may permit compositing among different
			 systems provided the 5-sample limit is maintained.
(iv) Compositing samples prior to GC
			 analysis.
(A) Add 5 ml or equal larger
			 amounts of each sample (up to 5 samples are allowed) to a 25 ml glass syringe.
			 Special precautions must be made to maintain zero headspace in the
			 syringe.
(B) The samples must be
			 cooled at 4°C during this step to minimize volatilization losses.
(C) Mix well and draw out a 5-ml aliquot for
			 analysis.
(D) Follow sample
			 introduction, purging, and desorption steps described in the method.
(E) If less than five samples are used for
			 compositing, a proportionately small syringe may be used.
(v) Compositing samples prior to GC/MS
			 analysis.
(A) Inject 5-ml or equal larger
			 amounts of each aqueous sample (up to 5 samples are allowed) into a 25-ml
			 purging device using the sample introduction technique described in the
			 method.
(B) The total volume of the
			 sample in the purging device must be 25 ml.
(C) Purge and desorb as described in the
			 method.
(o)
			 Compliance with Section N(2) above, shall be determined based on the analytical
			 results obtained at each sampling point. If one sampling point is in violation
			 of an MCL, the system is in violation of the MCL.
(i) For systems monitoring more than once per
			 year, compliance with the mcl is determined by a running annual average at each
			 sampling point.
(ii) Systems
			 monitoring annually or less frequently whose sample result exceeds the MCL must
			 begin quarterly sampling. The system will not be considered in violation of the
			 MCL until it has completed one year of quarterly sampling.
(iii) If any sample result will cause the
			 running annual average to exceed the MCL at any sampling point, the system is
			 out of compliance with the MCL immediately.
(iv) If a system fails to collect the
			 required number of samples, compliance will be based on the total number of
			 samples collected.
(v) If a sample
			 result is less than the detection limit, zero will be used to calculate the
			 annual average.
(p)
			 Analysis for the contaminants listed in Section N(2) above, shall be conducted
			 using EPA-approved methods listed in 40 CFR 141.
(q) Analysis under this section shall only be
			 conducted by laboratories that are certified by the Department.
(r) The Department may allow the use of
			 monitoring data collected after January 1, 1988, for purposes of initial
			 monitoring compliance. If the data are generally consistent with the other
			 requirements in this section, the Department may use those data (i.e., a single
			 sample rather than four quarterly samples) to satisfy the initial monitoring
			 requirement of paragraph (2)(d) of this section. Systems which use
			 grandfathered samples and did not detect any contaminant listed in Section
			 N(2)(b) through (u) above shall begin monitoring annually in accordance with
			 paragraph (2)(e) of this section beginning with the initial compliance
			 period.
(s) The Department may
			 increase required monitoring where necessary to detect variations within the
			 system.
(t) Each public water
			 system shall monitor at the time designated by the Department within each
			 compliance period.
(u) All new
			 systems or systems that use a new source of water that begin operation after
			 January 22, 2004 must demonstrate compliance with the MCL within a period of
			 time specified by the Department. The system must also comply with the initial
			 sampling frequencies specified by the Department to ensure a system can
			 demonstrate compliance with the MCL. Routine and increased monitoring
			 frequencies shall be conducted in accordance with the requirements in this
			 section.