Statutes, codes, and regulations
Delaware Administrative Code
Title 16 - Health and SafetyDepartment of Health and Social ServicesDivision of Public HealthHealth Systems Protection (HSP)
Public Drinking Water Systems
Section 4462-8.0 - Ground Water Rule

16 Del. Admin. Code § 4462-8.0

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Current through Register Vol. 28, No. 7, January 1, 2025
Section 4462-8.0 - Ground Water Rule
8.1 General requirements and applicability
8.1.1 Scope of this section. The requirements of the ground water rule constitute National Primary Drinking Water Regulations.
8.1.2 Applicability. This section applies to all public water systems that use ground water except that it does not apply to public water systems that combine all of their ground water with surface water or with ground water under the direct influence of surface water prior to treatment under subpart H. For the purposes of this section, "ground water system" is defined as any public water system meeting this applicability statement, including consecutive systems receiving finished ground water.
8.1.3 General requirements. Systems subject to this section must comply with the following requirements:
8.1.3.1 Sanitary survey information requirements for all ground water systems as described in subsection 8.2.
8.1.3.2 Microbial source water monitoring requirements for ground water systems that do not treat all of their ground water to at least 99.99 percent (4-log) treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer as described in subsection 8.3.
8.1.3.3 Treatment technique requirements, described in subsection 8.4, that apply to ground water systems that have fecally contaminated source waters, as determined by source water monitoring conducted under subsection 8.3, or that have significant deficiencies that are identified by the Division or that are identified by EPA under SDWA section 1445. A ground water system with fecally contaminated source water or with significant deficiencies subject to the treatment technique requirements of this section must implement one or more of the following corrective action options: correct all significant deficiencies; provide an alternate source of water; eliminate the source of contamination; or provide treatment that reliably achieves at least 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer.
8.1.3.4 Ground water systems that provide at least 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer are required to conduct compliance monitoring to demonstrate treatment effectiveness, as described in subsection 8.4.2.
8.1.3.5 If requested by the Division, ground water systems must provide the Division with any existing information that will enable the State to perform a hydrogeologic sensitivity assessment. For the purposes of this section, "hydrogeologic sensitivity assessment" is a determination of whether ground water systems obtain water from hydrogeologically sensitive settings.
8.1.4 Compliance date. Ground water systems must comply, unless otherwise noted, with the requirements of this section beginning December 1, 2009.
8.2 Sanitary surveys for ground water systems.
8.2.1 Ground water systems must provide the Division, at the Division's request, any existing information that will enable the Division to conduct a sanitary survey.
8.2.2 For the purposes of this section, a "sanitary survey," as conducted by the Division, includes but is not limited to, an onsite review of the water source(s) (identifying sources of contamination by using results of source water assessments or other relevant information where available), facilities, equipment, operation, maintenance, and monitoring compliance of a public water system to evaluate the adequacy of the system, its sources and operations and the distribution of safe drinking water.
8.2.3 The sanitary survey must include an evaluation of the applicable components listed in subsections 8.2.3.1 through 8.2.3.8:
8.2.3.1 Source;
8.2.3.2 Treatment;
8.2.3.3 Distribution system;
8.2.3.4 Finished water system;
8.2.3.5 Pumps, pump facilities, and controls;
8.2.3.6 Monitoring, reporting, and data verification;
8.2.3.7 System management and operation; and
8.2.3.8 Operator compliance with Division requirements.
8.3 Ground water source microbial monitoring and analytical methods.
8.3.1 Triggered source water monitoring.
8.3.1.1 General requirements. A ground water system must conduct triggered source water monitoring if the conditions identified in subsections 8.3 .1.1.1, 8.3.1.1.2 and 8.3.1.1.3 exist.
8.3.1.1.1 The system does not provide at least 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer for each ground water source; and
8.3.1.1.2 The system is notified that a sample collected under subsection 7.1 is total coliform-positive and the sample is not invalidated under subsection 7.2.2 until December 31, 2015.
8.3.1.1.3 The system is notified that a sample collected under subsection 7.4.7 is total coliform-positive and the sample is not invalidated under subsection 7.4.3.3 beginning January 1, 2016.
8.3.1.2 Sampling Requirements. A ground water system must collect, within 24 hours of notification of the total coliform-positive sample, at least one ground water source sample from each ground water source in use at the time the total coliform-positive sample was collected under subsection 7.1 until December 31, 2015, or collected under subsections 7.4.4 through 7.4.7 beginning January 1, 2016 except as provided in subsection 8.3 .1.2.2.
8.3.1.2.1 The Division may extend the 24-hour time limit on a case-by-case basis if the system cannot collect the ground water source water sample within 24 hours due to circumstances beyond its control. In the case of an extension, the Division must specify how much time the system has to collect the sample.
8.3.1.2.2 If approved by the Division, systems with more than one ground water source may meet the requirements of subsection 8.3.1.2 by sampling a representative ground water source or sources. If directed by the Division, systems must submit for Division approval a triggered source water monitoring plan that identifies one or more ground water sources that are representative of each monitoring site in the system's sample siting plan under subsection 7.1 until December 31, 2015, or under subsection 7.4.3 beginning January 1, 2016 and that the system intends to use for representative sampling under this paragraph.
8.3.1.2.3 Until December 31, 2015 a ground water system serving 1,000 people or fewer may use a repeat sample collected from a ground water source to meet both the requirements of subsection 7.2.3 and to satisfy the monitoring requirements of subsection 8.3.1.2 for that ground water source only if the Division approves the use of E. coli as a fecal indicator for source water monitoring under subsection 8.3.1. If the repeat sample collected from the ground water source is E. coli-positive, the system must comply with subsection 8.3.1.3.
8.3.1.2.4 Beginning January 1, 2016 a ground water system serving 1,000 or fewer people may use a repeat sample collected from a ground water source to meet both the requirements of subsection 7.4 and to satisfy the monitoring requirements of subsection 8.3.1.2 for that ground water source only if the Division approves the use of E. coli as a fecal indicator for source water monitoring under subsection 8.3.1 and approves the use of a single sample for meeting both the triggered source water monitoring requirements in subsection 8.3.1 and the repeat monitoring requirements in subsection 7.4.8. If the repeat sample collected from the ground water source is E. coli-positive, the system must comply with subsection 8.3 .1.3.
8.3.1.3 Additional Requirements. If the Division does not require corrective action under subsection 8.4.1.2 for a fecal indicator-positive source water sample collected under subsection 8.3.1.2 that is not invalidated under subsection 8.3.4, the system must collect five additional source water samples from the same source within 24 hours of being notified of the fecal indicator-positive sample.
8.3.1.4 Consecutive and Wholesale Systems.
8.3.1.4.1 In addition to the other requirements of subsection 8.3.1, a consecutive ground water system that has a total coliform-positive sample collected under subsection 7.1 until December 31, 2015 or under subsections 7.4 .4 through 7.4.7 beginning January 1, 2016 must notify the wholesale system(s) within 24 hours of being notified of the total coliform-positive sample.
8.3.1.4.2 In addition to the other requirements of subsection 8.3.1, a wholesale ground water system must comply with subsections 8.3.1.4.2.1 and 8.3.1.4.2.2.
8.3.1.4.2.1 A wholesale ground water system that receives notice from a consecutive system it serves that a sample collected under subsection 7.11 until December 31, 2015 or under subsections 7.4.4 through 7.4.7 beginning January 1, 2016 is total coliform-positive must, within 24 hours of being notified, collect a sample from its ground water source(s) under subsection 8.3 .1.2 and analyze it for a fecal indicator under subsection 8.3 .3.
8.3.1.4.2.2 If the sample collected under subsection 8.3.1.4.2.1 is fecal indicator-positive, the wholesale ground water system must notify all consecutive systems served by that ground water source of the fecal indicator source water positive within 24 hours of being notified of the ground water source sample monitoring result and must meet the requirements of subsection 8.3.1.3.
8.3.1.5 Exceptions to the Triggered Source Water Monitoring Requirements. A ground water system is not required to comply with the source water monitoring requirements of subsection 8.3.1 if either of the following conditions exists:
8.3.1.5.1 The Division determines, and documents in writing, that the total coliform-positive sample collected under subsection 7.1 1 until December 31, 2015 or under subsections 7.4.4 through 7.4.7 beginning January 1, 2016 is caused by a distribution system deficiency; or
8.3.1.5.2 The total coliform-positive sample collected under subsection 7.1 1 until December 31, 2015 or under subsections 7.4.4 through 7.4.7 beginning January 1, 2016 is collected at a location that meets Division criteria for distribution system conditions that will cause total coliform-positive samples.
8.3.2 Assessment Source Water Monitoring. If directed by the Division, ground water systems must conduct assessment source water monitoring that meets Division-determined requirements for such monitoring. A ground water system conducting assessment source water monitoring may use a triggered source water sample collected under subsection 8.3.1.2 to meet the requirements of subsection 8.3.2. Division-determined assessment source water monitoring requirements may include:
8.3.2.1 Collection of a total of 12 ground water source samples that represent each month the system provides ground water to the public;
8.3.2.2 Collection of samples from each well unless the system obtains written Division approval to conduct monitoring at one or more wells within the ground water system that are representative of multiple wells used by that system and that draw water from the same hydrogeologic setting;
8.3.2.3 Collection of a standard sample volume of at least 100 mL for fecal indicator analysis regardless of the fecal indicator or analytical method used;
8.3.2.4 Analysis of all ground water source samples using one of the analytical methods listed in subsection 8.3.3.2 for the presence of E. coli, enterococci, or coliphage;
8.3.2.5 Collection of ground water source samples at a location prior to any treatment of the ground water source unless the Division approves a sampling location after treatment; and
8.3.2.6 Collection of ground water source samples at the well itself unless the system's configuration does not allow for sampling at the well itself and the Division approves an alternate sampling location that is representative of the water quality of that well.
8.3.3 Analytical methods.
8.3.3.1 A ground water system subject to the source water monitoring requirements of subsection 8.3.1 must collect a standard sample volume of at least 100 mL for fecal indicator analysis regardless of the fecal indicator or analytical method used.
8.3.3.2 A ground water system must analyze all ground water source samples collected under subsection 8.3.1 using one of the analytical methods listed in the following table for the presence of E. coli enterococci, or coliphage: Analytical Methods for Source Water Monitoring

Fecal Indicator1 Methodology Method Citation
E. coli

Colilert3

Colisure3

Membrane Filter Method with MI Agar

m-Coliblue24 Test5

E*Colite Test6

EC-MUG7

NA-MUG7

9223 B.2

9223 B.2

EPA Method 16044

9221 F.2

9222 G.2

Enterococci

Multiple Tube Technique

Membrane Filter Technique3

Membrane Filter Technique

Enterolert9.........................................................

9230B.2

9230C.2

EPA Method 16008

Coliphage Two-Step Enrichment Presence-Absence Procedure Single Agar Layer Procedure

EPA Method 1601.10

EPA Method 1602.11

Analyses must be conducted in accordance with the documents listed below. The Director of the Federal Register approves the incorporation by reference of the documents listed in footnotes 2-11 in accordance with 5 U.S.C. 552(a) and 1 CFR part 51 . Copies of the documents may be obtained from the sources listed below. Copies may be inspected at EPA's Drinking Water Docket, EPA West, 1301 Constitution Avenue, NW., EPA West, Room B102, Washington DC 20460 (Telephone: 202-566-2426); or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

1 The time from sample collection to initiation of analysis may not exceed 30 hours. The ground water system is encouraged but is not required to hold samples below 10 o C during transit.

2 Methods are described in Standard Methods for the Examination of Water and Wastewater 20th edition (1998) and copies may be obtained from the American Public Health Association, 1015 Fifteenth Street, NW., Washington, DC 20005-2605.

3 Medium is available through IDEXX Laboratories, Inc., One IDEXX Drive, Westbrook, Maine 04092.

4 EPA Method 1604: Total Coliforms and Escherichia coli in Water by Membrane Filtration Using a Simultaneous Detection Technique (MI Medium); September 2002, EPA 821-R-02-024. Method is available at http://www.epa.gov/nerlcwww/1604sp02.pdf or from EPA's Water Resource Center (RC-4100T), 1200 Pennsylvania Avenue, NW., Washington, DC 20460.

5 A description of the m-ColiBlue24 Test, "Total Coliforms and E. coli Membrane Filtration Method with m-ColiBlue24[reg] Broth, "Method No. 10029 Revision 2, August 17, 1999, is available from Hach Company, 100 Dayton Ave., Ames, IA 50010 or from EPA's Water Resource Center (RC-4100T), 1200 Pennsylvania Avenue, NW., Washington, DC 20460.

6 A description of the E*Colite Test, "Charm E*Colite Presence/ Absence Test for Detection and Identification of Coliform Bacteria and Escherichia coli in Drinking Water, January 9, 1998, is available from Charm Sciences, Inc., 659 Andover St., Lawrence, MA 01843-1032 or from EPA's Water Resource Center (RC-4100T), 1200 Pennsylvania Avenue, NW., Washington, DC 20460.

7 EC-MUG (Method 9221F) or NA-MUG (Method 9222G) can be used for E. coli testing step as described in Sec. 141.21(f)(6)(i) or (ii) after use of Standard Methods 9221 B, 9221 D, 9222 B, or 9222 C.

8 EPA Method 1600: Enterococci in Water by Membrane Filtration Using membrane-Enterococcus Indoxyl-[beta]-D-Glucoside Agar (mEI) EPA 821-R-02-022 (September 2002) is an approved variation of Standard Method 9230C. The method is available at http://www.epa.gov/nerlcwww/1600sp02.pdf or from EPA's Water Resource Center (RC-4100T), 1200 Pennsylvania Avenue, NW., Washington, DC 20460. The holding time and temperature for ground water samples are specified in footnote 1 above, rather than as specified in section 8 of EPA Method 1600.

9 Medium is available through IDEXX Laboratories, Inc., One IDEXX Drive, Westbrook, Maine 04092. Preparation and use of the medium is set forth in the article "Evaluation of Enterolert for Enumeration of Enterococci in Recreational Waters," by Budnick, G.E., Howard, R.T., and Mayo, D.R., 1996, Applied and Environmental Microbiology, 62:3881-3884.

10 EPA Method 1601: Male-specific (F+) and Somatic Coliphage in Water by Two-step Enrichment Procedure; April 2001, EPA 821-R-01-030. Method is available at http://www.epa.gov/nerlcwww/1601ap01.pdf or from EPA's Water Resource Center (RC-4100T), 1200 Pennsylvania Avenue, NW., Washington, DC 20460.

11 EPA Method 1602: Male-specific (F+) and Somatic Coliphage in Water by Single Agar Layer (SAL) Procedure; April 2001, EPA 821-R-01-029. Method is available at http://www.epa.gov/nerlcwww/1602ap01.pdf or from EPA's Water Resource Center (RC-4100T), 1200 Pennsylvania Avenue, NW., Washington, DC 20460.

8.3.4 Invalidation of a fecal indicator-positive ground water source sample.
8.3.4.1 A ground water system may obtain Division invalidation of a fecal indicator-positive ground water source sample collected under subsection 8.3.1 only under the conditions specified in subsections 8.3.4.1.1 and 8.3.4.1.2.
8.3.4.1.1 The system provides the Division with written notice from the laboratory that improper sample analysis occurred; or
8.3.4.1.2 The Division determines and documents in writing that there is substantial evidence that a fecal indicator-positive ground water source sample is not related to source water quality.
8.3.4.2 If the Division invalidates a fecal indicator-positive ground water source sample, the ground water system must collect another source water sample under subsection 8.3.1 within 24 hours of being notified by the Division of its invalidation decision and have it analyzed for the same fecal indicator using the analytical methods in subsection 8.3.3. The Division may extend the 24-hour time limit on a case-by-case basis if the system cannot collect the source water sample within 24 hours due to circumstances beyond its control. In the case of an extension, the Division must specify how much time the system has to collect the sample.
8.3.5 Sampling location.
8.3.5.1 Any ground water source sample required under subsection 8.3.1 must be collected at a location prior to any treatment of the ground water source unless the Division approves a sampling location after treatment.
8.3.5.2 If the system's configuration does not allow for sampling at the well itself, the system may collect a sample at a Division-approved location to meet the requirements of subsection 8.3.1 if the sample is representative of the water quality of that well.
8.3.6 New Sources. If directed by the Division, a ground water system that places a new ground water source into service after November 30, 2009, must conduct assessment source water monitoring under subsection 8.3.2. If directed by the Division, the system must begin monitoring before the ground water source is used to provide water to the public.
8.3.7 Public Notification. A ground water system with a ground water source sample collected under subsections 8.3.1 or 8.3.2 that is fecal indicator-positive and that is not invalidated under subsection 8.3 .4, including consecutive systems served by the ground water source, must conduct public notification under subsection 4.2 .1.1.1.
8.3.8 Monitoring Violations. Failure to meet the requirements of subsections 8.3.1 through 8.3.6 is a monitoring violation and requires the ground water system to provide public notification under subsection 4.2 .1.1.3.
8.4 Treatment technique requirements for ground water systems.
8.4.1 Ground water systems with significant deficiencies or source water fecal contamination.
8.4.1.1 The treatment technique requirements of this section must be met by ground water systems when a significant deficiency is identified or when a ground water source sample collected under subsection 8.3.1.3 is fecal indicator-positive.
8.4.1.2 If directed by the Division, a ground water system with a ground water source sample collected under subsection 8.3.1.2, subsection 8.3.1.4, or subsection 8.3.2 that is fecal indicator-positive must comply with the treatment technique requirements of this subsection.
8.4.1.3 When a significant deficiency is identified at a Subpart H public water system that uses both ground water and surface water or ground water under the direct influence of surface water, the system must comply with provisions of subsection 8.4 except in cases where the Division determines that the significant deficiency is in a portion of the distribution system that is served solely by surface water or ground water under the direct influence of surface water.
8.4.1.4 Unless the Division directs the ground water system to implement a specific corrective action, the ground water system must consult with the Division regarding the appropriate corrective action within 30 days of receiving written notice from the Division of a significant deficiency, written notice from a laboratory that a ground water source sample collected under subsection 8.3.1.3 was found to be fecal indicator-positive, or direction from the Division that a fecal indicator-positive collected under subsection 8.3.1.2, subsection 8.3.1.4, or subsection 8.3.2 requires corrective action. For the purposes of this section, significant deficiencies include, but are not limited to, defects in design, operation, or maintenance, or a failure or malfunction of the sources, treatment, storage, or distribution system that the Division determines to be causing, or have potential for causing, the introduction of contamination into the water delivered to consumers.
8.4.1.5 Within 120 days (or earlier if directed by the Division) of receiving written notification from the Division of a significant deficiency, written notice from a laboratory that a ground water source sample collected under subsection 8.3.1.3 was found to be fecal indicator-positive, or direction from the Division that a fecal indicator-positive sample collected under subsection 8.3.1.2, subsection 8.3.1.4, or subsection 8.3.2 requires corrective action, the ground water system must either:
8.4.1.5.1 Have completed corrective action in accordance with applicable Division plan review processes or other Division guidance or direction, if any, including Division-specified interim measures; or
8.4.1.5.2 Be in compliance with a Division-approved corrective action plan and schedule subject to the conditions specified in subsections 8.4.1.5.2.1 and 8.4.1.5.2.2.
8.4.1.5.2.1 Any subsequent modifications to a Division-approved corrective action plan and schedule must also be approved by the Division.
8.4.1.5.2.2 If the Division specifies interim measures for protection of the public health pending Division approval of the corrective action plan and schedule or pending completion of the corrective action plan, the system must comply with these interim measures as well as with any schedule specified by the Division.
8.4.1.6 Corrective Action Alternatives. Ground water systems that meet the conditions of subsections 8.4.1.1 or 8.4.1.2 must implement one or more of the following corrective action alternatives:
8.4.1.6.1 Correct all significant deficiencies;
8.4.1.6.2 Provide an alternate source of water;
8.4.1.6.3 Eliminate the source of contamination; or
8.4.1.6.4 Provide treatment that reliably achieves at least 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer for the ground water source.
8.4.1.7 Special notice to the public of significant deficiencies or source water fecal contamination.
8.4.1.7.1 In addition to the applicable public notification requirements of subsection 4.2 .1.1.1, a community ground water system that receives notice from the Division of a significant deficiency or notification of a fecal indicator-positive ground water source sample that is not invalidated by the Division under subsection 8.3.4 must inform the public served by the water system under subsection 4.3.3.8.6 of the fecal indicator-positive source sample or of any significant deficiency that has not been corrected. The system must continue to inform the public annually until the significant deficiency is corrected or the fecal contamination in the ground water source is determined by the Division to be corrected under subsection 8.4.1.5.
8.4.1.7.2 In addition to the applicable public notification requirements of subsection 4.2.1.1.1, a non-community ground water system that receives notice from the Division of a significant deficiency must inform the public served by the water system in a manner approved by the Division of any significant deficiency that has not been corrected within 12 months of being notified by the Division, or earlier if directed by the Division. The system must continue to inform the public annually until the significant deficiency is corrected. The information must include:
8.4.1.7.2.1 The nature of the significant deficiency and the date the significant deficiency was identified by the Division;
8.4.1.7.2.2 The Division-approved plan and schedule for correction of the significant deficiency, including interim measures, progress to date, and any interim measures completed; and
8.4.1.7.2.3 For systems with a large proportion of non-English speaking consumers, as determined by the Division, information in the appropriate language(s) regarding the importance of the notice or a telephone number or address where consumers may contact the system to obtain a translated copy of the notice or assistance in the appropriate language.
8.4.1.7.3 If directed by the Division, a non-community water system with significant deficiencies that have been corrected must inform its customers of the significant deficiencies, how the deficiencies were corrected, and the dates of correction under subsection 8.4.1.7.2.
8.4.2 Compliance monitoring
8.4.2.1 Existing ground water sources. A ground water system that is not required to meet the source water monitoring requirements of this subsection for any ground water source because it provides at least 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer for any ground water source before December 1, 2009, must notify the Division in writing that it provides at least 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer for the specified ground water source and begin compliance monitoring in accordance with subsection 8.4.2.3 by December 1, 2009. Notification to the Division must include engineering, operational, or other information that the Division requests to evaluate the submission. If the system subsequently discontinues 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer for a ground water source, the system must conduct ground water source monitoring as required under subsection 8.3.
8.4.2.2 New ground water sources. A ground water system that places a ground water source in service after November 30, 2009, that is not required to meet the source water monitoring requirements of this subsection because the system provides at least 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer for the ground water source must comply with the requirements of subsections 8.4.2.2.1, 8.4.2.2.2 and 8.4.2.2.3.
8.4.2.2.1 The system must notify the Division in writing that it provides at least 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer for the ground water source. Notification to the Division must include engineering, operational, or other information that the division requests to evaluate the submission.
8.4.2.2.2 The system must conduct compliance monitoring as required under subsection 8.4.2.3 within 30 days of placing the source in service.
8.4.2.2.3 The system must conduct ground water source monitoring under subsection 8.3 if the system subsequently discontinues 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer for the ground water source.
8.4.2.3 Monitoring requirements. A ground water system subject to the requirements of subsections 8.4 .2.1, 8.4.2.2.1 or 8.4.2.2.2 must monitor the effectiveness and reliability of treatment for that ground water source before or at the first customer as follows:
8.4.2.3.1 Chemical disinfection
8.4.2.3.1.1 Ground water systems serving greater than 3,300 people. A ground water system that serves greater than 3,300 people must continuously monitor the residual disinfectant concentration using analytical methods specified in subsection 1.19.2 at a location approved by the Division and must record the lowest residual disinfectant concentration each day that water from the ground water source is served to the public. The ground water system must maintain the Division-determined residual disinfectant concentration every day the ground water system serves water from the ground water source to the public. If there is a failure in the continuous monitoring equipment, the ground water system must conduct grab sampling every four hours until the continuous monitoring equipment is returned to service. The system must resume continuous residual disinfectant monitoring within 14 days.
8.4.2.3.1.2 Ground water systems serving 3,300 or fewer people. A ground water system that serves 3,300 or fewer people must monitor the residual disinfectant concentration using analytical methods specified in subsection 1.19.2 at a location approved by the Division and record the residual disinfection concentration each day that water from the ground water source is served to the public. The ground water system must maintain the Division-determined residual disinfectant concentration every day the ground water system serves water from the ground water source to the public. The ground water system must take a daily grab sample during the hour of peak flow or at another time specified by the Division. If any daily grab sample measurement falls below the Division-determined residual disinfectant concentration, the ground water system must take follow-up samples every four hours until the residual disinfectant concentration is restored to the Division-determined level. Alternatively, a ground water system that serves 3,300 or fewer people may monitor continuously and meet the requirements of subsection 8.4.2.3.1.1.
8.4.2.3.2 Membrane filtration. A ground water system that uses membrane filtration to meet the requirements of this section must monitor the membrane filtration process in accordance with all Division-specified monitoring requirements and must operate the membrane filtration in accordance with all Division-specified compliance requirements. A ground water system that uses membrane filtration is in compliance with the requirement to achieve at least 4-log removal of viruses when:
8.4.2.3.2.1 The membrane has an absolute molecular weight cut-off (MWCO), or an alternate parameter that describes the exclusion characteristics of the membrane, that can reliably achieve at least 4-log removal of viruses;
8.4.2.3.2.2 The membrane process is operated in accordance with Division-specified compliance requirements; and
8.4.2.3.2.3 The integrity of the membrane is intact.
8.4.2.3.3 Alternative treatment. A ground water system that uses a Division-approved alternative treatment to meet the requirements of this section by providing at least 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer must:
8.4.2.3.3.1 Monitor the alternative treatment in accordance with all Division-specified monitoring requirements; and
8.4.2.3.3.2 Operate the alternative treatment in accordance with all compliance requirements that the Division determines to be necessary to achieve at least 4-log treatment of viruses.
8.4.3 Discontinuing treatment. A ground water system may discontinue 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer for a ground water source if the Division determines and documents in writing that 4-log treatment of viruses is no longer necessary for that ground water source. A system that discontinues 4-log treatment of viruses is subject to the source water monitoring and analytical methods requirements of subsection 8.3.
8.4.4 Failure to meet the monitoring requirements of subsection 8.4.2.1 is a monitoring violation and requires the ground water system to provide public notification under subsection 4.2.1.1.3.
8.5 Treatment technique violations for ground water systems.
8.5.1 A ground water system with a significant deficiency is in violation of the treatment technique requirement if, within 120 days (or earlier if directed by the Division) of receiving written notice from the Division of the significant deficiency, the system:
8.5.1.1 Does not complete corrective action in accordance with any applicable Division plan review processes or other Division guidance and direction, including Division specified interim actions and measures; or
8.5.1.2 Is not in compliance with a Division-approved corrective action plan and schedule.
8.5.2 Unless the Division invalidates a fecal indicator-positive ground water source sample under subsection 8.3.4, a ground water system is in violation of the treatment technique requirement if, within 120 days (or earlier if directed by the Division) of meeting the conditions of subsection 8.4.1.1 or subsection 8.4.1.2, the system:
8.5.2.1 Does not complete corrective action in accordance with any applicable Division plan review processes or other Division guidance and direction, including Division-specified interim measures; or
8.5.2.2 Is not in compliance with a Division-approved corrective action plan and schedule.
8.5.3 A ground water system subject to the requirements of subsection 8.4.2.3 that fails to maintain at least 4-log treatment of viruses (using inactivation, removal, or a Division-approved combination of 4-log virus inactivation and removal) before or at the first customer for a ground water source is in violation of the treatment technique requirement if the failure is not corrected within four hours of determining the system is not maintaining at least 4-log treatment of viruses before or at the first customer.
8.5.4 Ground water system must give public notification under subsection 4.2.1.1.2 for the treatment technique violations specified in subsections 8.5.1, 8.5.2 and 8.5.3.
8.6 Reporting and recordkeeping for ground water systems.
8.6.1 Reporting. In addition to the requirements of subsection 4.1, a ground water system regulated under this section must provide the following information to the Division:
8.6.1.1 A ground water system conducting compliance monitoring under subsection 8.4.2 must notify the Division any time the system fails to meet any Division-specified requirements including, but not limited to, minimum residual disinfectant concentration, membrane operating criteria or membrane integrity, and alternative treatment operating criteria, if operation in accordance with the criteria or requirements is not restored within four hours. The ground water system must notify the Division as soon as possible, but in no case later than the end of the next business day.
8.6.1.2 After completing any corrective action under subsection 8.4.1, a ground water system must notify the Division within 30 days of completion of the corrective action.
8.6.1.3 If a ground water system subject to the requirements of subsection 8.3.1 does not conduct source water monitoring under subsection 8.3.1.5.3, the system must provide documentation to the Division within 30 days of the total coliform positive sample that it met the Division criteria.
8.6.2 Recordkeeping. In addition to the requirements of Section 5.0, a ground water system regulated under this section must maintain the following information in its records:
8.6.2.1 Documentation of corrective actions. Documentation shall be kept for a period of not less than ten years.
8.6.2.2 Documentation of notice to the public as required under subsection 8.4.1.7. Documentation shall be kept for a period of not less than three years.
8.6.2.3 Records of decisions under subsection 8.3.1.5.2 and records of invalidation of fecal indicator-positive ground water source samples under subsection 8.3.4. Documentation shall be kept for a period of not less than five years.
8.6.2.4 For consecutive systems, documentation of notification to the wholesale system(s) of total-coliform positive samples that are not invalidated under subsection 7.2.2 until December 31, 2015, or under subsection 7.4 .3. Documentation shall be kept for a period of not less than five years.
8.6.2.5 For systems, including wholesale systems, that are required to perform compliance monitoring under subsection 8.4.2:
8.6.2.5.1 Records of the Division-specified minimum disinfectant residual. Documentation shall be kept for a period of not less than ten years.
8.6.2.5.2 Records of the lowest daily residual disinfectant concentration and records of the date and duration of any failure to maintain the Division-prescribed minimum residual disinfectant concentration for a period of more than four hours. Documentation shall be kept for a period of not less than five years.
8.6.2.5.3 Records of Division-specified compliance requirements for membrane filtration and of parameters specified by the Division for Division-approved alternative treatment and records of the date and duration of any failure to meet the membrane operating, membrane integrity, or alternative treatment operating requirements for more than four hours. Documentation shall be kept for a period of not less than five years.

16 Del. Admin. Code § 4462-8.0

24 DE Reg. 794 (2/1/2021)
24 DE Reg. 904( 4/1/2021) (Errata)