Md. Code Regs. 26.04.01.11

Current through Register Vol. 51, No. 24, December 2, 2024

Section 26.04.01.11 - Microbiological Contaminant Sampling and Analytical Requirements for Total Coliform

A. Routine Monitoring for Total Coliform of Community and Noncommunity Water Supply Systems Until March 31, 2016.

(1) A supplier of water to a community water system shall sample for total coliform at regular intervals throughout the month and in number proportionate to the population served as set forth in the coliform sample table in §A(2) of this regulation.

(2) Coliform Sample Table.

Population Served	Minimum Number of Samples Per Month
25 to 1,000¹	1
1,001 to 2,500	2
2,501 to 3,300	3
3,301 to 4,100	4
4,101 to 4,900	5
4,901 to 5,800	6
5,801 to 6,700	7
6,701 to 7,600	8
7,601 to 8,500	9
8,501 to 12,900	10
12,901 to 17,200	15
17,201 to 21,500	20
21,501 to 25,000	25
25,001 to 33,000	30
33,001 to 41,000	40
41,001 to 50,000	50
50,001 to 59,000	60
59,001 to 70,000	70
70,001 to 83,000	80
83,001 to 96,000	90
96,001 to 130,000	100
130,001 to 220,000	120
220,001 to 320,000	150
320,001 to 450,000	180
450,001 to 600,000	210
600,001 to 780,000	240
780,001 to 970,000	270
970,001 to 1,230,000	300
1,230,001 to 1,520,000	330
1,520,001 to 1,850,000	360
1,850,001 to 2,270,000	390
2,270,001 to 3,020,000	420
3,020,001 to 3,960,000	450
3,960,001 or more	480
¹ Includes public water systems which have at least 15 service connections, but serve fewer than 25 persons.

(3) A supplier of water to a noncommunity system shall:

(a) Sample for total coliform once a quarter if the system serves 25 to 1,000 persons and uses only ground water not under the direct influence of surface water; or

(b) Comply with §A(1) of this regulation, if the system:

(i) Serves more than 1,000 persons;

(ii) Uses surface water in total or in part; or

(iii) Uses ground water under the direct influence of surface water.

(4) A noncommunity water supply system shall comply with §A(1) of this regulation within 6 months after the Approving Authority determines the ground water is under the direct influence of surface water.

(5) A supplier of water shall sample for total coliform at points which are representative of conditions within the distribution system and in accordance with a sampling siting plan written by the supplier of water. The Approving Authority may revise or review this plan.

(6) A supplier of water shall monitor for total coliform at regular intervals throughout the month, except if a system uses only ground water and serves less than 4,901 individuals, then the system may collect all required routine samples on 1 day from different sites.

B. Alternative Routine Monitoring Frequency for Total Coliform Until March 31, 2016.

(1) Public water systems that use surface water or ground water under the direct influence of surface water and that avoid filtration are required to collect at least one total coliform sample near the first service connection each day the source water turbidity exceeds 1 nephelometric turbidity unit (NTU). This sample shall be collected within 24 hours of the turbidity measurement. The Approving Authority may waive the 24-hour requirement under 40 CFR § 141.21(a)(5), which is incorporated by reference.

(2) The Approving Authority may reduce the total coliform sampling frequency of a community or noncommunity water system if the:

(a) System serves less than 1,000 individuals;

(b) System has a history of no coliform bacterial contamination in its current configuration;

(c) System is supplied solely by a protected ground water source;

(d) System is free of significant sanitary defects based on a sanitary survey conducted within 5 years; and

(e) Reduction is granted in writing.

(3) Sampling frequency for total coliform may not be reduced to less than once a:

(a) Quarter for community systems; and

(b) Year for noncommunity systems.

(4) The Approving Authority may reduce total coliform sampling frequency for a noncommunity system using only ground water that regularly serves more than 1,000 individuals for those months when the population served falls below 1,000 individuals.

C. Analytical Requirements for Total Coliform Analysis Until March 31, 2016.

(1) Total coliform analysis shall be conducted in accordance with methods specified in 40 CFR § 141.21(f), which is incorporated by reference.

(2) The total coliform samples need only to be analyzed for the presence or absence of total coliform and the standard sample size shall be at least 100 milliliters, regardless of analytical method.

D. Compliance Monitoring for Ground Water Supplies.

(1) Existing Ground Water Sources. A ground water supplier that provides at least 4-log treatment of viruses, using inactivation, removal, or a combination of 4-log virus inactivation and removal approved by the Approving Authority, before or at the first customer for any ground water source before December 1, 2009, shall notify the Approving Authority in writing that it provides at least 4-log treatment of viruses, and begin compliance monitoring in accordance with §D(3) of this regulation. Notification to the Approving Authority shall include engineering, operational, or other information that the Approving Authority requests to evaluate the submission. If the supplier subsequently discontinues 4-log treatment of viruses, the supplier shall conduct ground water source monitoring as required under Regulation .11-2 D-J of this chapter.

(2) New Ground Water Sources. A ground water supplier that places a ground water source in service after November 30, 2009, and that provides at least 4-log treatment of viruses, using inactivation, removal, or a combination of 4-log virus inactivation and removal approved by the Approving Authority, before or at the first customer for the ground water source shall comply with the following requirements:

(a) The supplier shall notify the Approving Authority in writing that it provides at least 4-log treatment of viruses, using inactivation, removal, or a combination of 4-log virus inactivation and removal approved by the Approving Authority, before or at the first customer for the ground water source. Notification to the Approving Authority shall include engineering, operational, or other information that the Approving Authority requests to evaluate the submission.

(b) The supplier shall conduct compliance monitoring as required under §D(3) of this regulation within 30 days of placing the source in service.

(c) The supplier shall conduct ground water source monitoring required under Regulation .11-2 D-J of this chapter if the supplier subsequently discontinues 4-log treatment of viruses.

(3) Monitoring requirements. A ground water supplier subject to the requirements of Regulation .05-5C of this chapter, or §D(1) or (2) of this regulation shall monitor the effectiveness and reliability of treatment for that ground water source before or at the first customer as follows:

(a) Chemical Disinfection.

(i) Ground Water Suppliers Serving Greater Than 3,300 People. A ground water supplier that serves greater than 3,300 people shall continuously monitor the residual disinfectant concentration using analytical methods specified in 40 CFR § 141.74(a)(2) at a location approved by the Approving Authority and shall record the lowest residual disinfectant concentration each day that water from the ground water source is served to the public. The ground water supplier shall maintain the Approving Authority-determined residual disinfectant concentration every day the ground water supplier serves water from the ground water source to the public. If there is a failure in the continuous monitoring equipment, the ground water supplier shall conduct grab sampling every four hours until the continuous monitoring equipment is returned to service. The supplier shall resume continuous residual disinfectant monitoring within 14 days.

(ii) Ground water suppliers serving 3,300 or fewer people. A ground water supplier that serves 3,300 or fewer people shall monitor the residual disinfectant concentration using analytical methods specified in 40 CFR § 141.74(a)(2) at a location approved by the Approving Authority and record the residual disinfection concentration each day that water from the ground water source is served to the public. The ground water supplier shall maintain the approved residual disinfectant concentration every day the ground water supplier serves water from the ground water source to the public. The ground water supplier shall take a daily grab sample during the hour of peak flow or at another time specified by the Approving Authority. If any daily grab sample measurement falls below the minimum residual disinfectant concentration, the ground water supplier shall take follow-up samples every 4 hours until the residual disinfectant concentration is restored to the approved minimum level. Alternatively, a ground water supplier that serves 3,300 or fewer people may monitor continuously and meet the requirements of §D(3)(a)(i) of this regulation.

(b) Membrane Filtration. A ground water supplier that uses membrane filtration to meet the requirements of this regulation shall monitor the membrane filtration process and shall operate the membrane filtration in accordance with all Approving Authority-specified requirements. A ground water supplier that uses membrane filtration is in compliance with the requirement to achieve at least 4-log removal of viruses when the requirements of 40 CFR § 141.403(b)(3)(ii)(A) -(C) are met.

(c) Alternative Treatment. A ground water supplier that uses an approved alternative treatment to meet the requirements of 40 CFR 141 Subpart S by providing at least 4-log treatment of viruses, using inactivation, removal, or a combination of 4-log virus inactivation and removal approved by the Approving Authority, before or at the first customer shall monitor and operate the alternative treatment in accordance with all Approving Authority-specified compliance requirements.

(4) Discontinuing Treatment. A ground water supplier may discontinue 4-log treatment of viruses, using inactivation, removal, or a combination of 4-log virus inactivation and removal approved by the Approving Authority, before or at the first customer for a ground water source if the Approving Authority determines and documents in writing that 4-log treatment of viruses is no longer necessary for that ground water source. A supplier that discontinues 4-log treatment of viruses is subject to the source water monitoring and analytical method requirements of Regulation .11-2 D-J of this chapter.

(5) Failure to meet the monitoring requirements of this regulation is a monitoring violation and requires the ground water supplier to provide public notification under Regulation .20D(1)(a) of this chapter.

Md. Code Regs. 26.04.01.11

Regulations .11 and new Regulation .11 adopted effective December 21, 1992 (19:25 Md. R. 2208)
Regulations .11 amended effective August 10, 1987 (14:16 Md. R. 1774)
Regulation .11D adopted effective March 7, 2011 (38:5 Md. R. 319); amended effective 43:17 Md. R. 957, eff. 8/29/2016