California Code of Regulations › Title 22 - Social Security › Division 4 - Environmental Health › Chapter 3 - Water Recycling Criteria › Article 5.1 - Indirect Potable Reuse: Groundwater Replenishment - Surface Application › Section 60320.124 - Response Retention Time

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
(a) The recycled municipal wastewater applied
				  by a GRRP shall be retained underground for a period of time necessary to allow
				  a project sponsor sufficient response time to identify treatment failures and
				  implement actions, including those required pursuant to section
				  60320.100(b),
				  necessary for the protection of public health.
(b) The response retention time required in
				  subsection (a) must be approved by the Department, based on information
				  provided in the engineering report required pursuant to section
				  60323. The response retention time
				  shall be no less than two months.
(c) To demonstrate the retention time
				  underground is no less than the response retention time approved pursuant to
				  subsection (b), a tracer study utilizing an added tracer shall be implemented
				  under hydraulic conditions representative of normal GRRP operations. With
				  Department approval, an intrinsic tracer may be used in lieu of an added
				  tracer. For each month of retention time estimated utilizing the approved
				  intrinsic tracer, a project sponsor shall receive no more than 0.67 months
				  credit. The retention time shall be the time representing the difference from
				  when the water with the tracer is applied at the GRRP to when either; two
				  percent (2%) of the initially introduced tracer concentration has reached the
				  downgradient monitoring point, or ten percent (10%) of the peak tracer unit
				  value observed at the downgradient monitoring point reaches the monitoring
				  point. A project sponsor for a GRRP shall initiate the tracer study prior to
				  the end of the third month of operation. A project sponsor for a GRRP permitted
				  on or before June 18, 2014 that has not performed a tracer study shall complete
				  a tracer study demonstrating the retention time underground.
(d) For the purpose of siting a GRRP location
				  during project planning and until a GRRP's project sponsor has met the
				  requirements of subsection (c), for each month of retention time estimated
				  using the method in column 1, the recycled municipal wastewater or recharge
				  water may be credited with no more than the corresponding response time in
				  column 2 of Table 60320.124.
Table 60320.124
Column
								1
Column
								2
Method used to
								estimate the retention time
Response Time Credit
								per Month
Tracer study utilizing an added
							 tracer.1
1.0 month
Tracer study utilizing an intrinsic
							 tracer.1
0.67 month
Numerical modeling consisting of calibrated finite
							 element or finite difference models using validated and verified computer codes
							 used for simulating groundwater flow.
0.50 month
Analytical modeling using existing
							 academically-accepted equations such as Darcy's Law to estimate groundwater
							 flow conditions based on simplifying aquifer assumptions.
0.25
							 month
1 The
							 retention time shall be the time representing the difference from when the
							 water with the tracer is applied at the GRRP to when either; two percent (2%)
							 of the initially introduced tracer concentration has reached the downgradient
							 monitoring point, or ten percent (10%) of the peak tracer unit value observed
							 at the downgradient monitoring point reaches the monitoring point.
(e)
				  A project sponsor shall obtain Department approval for the protocol(s) to be
				  used to establish the retention times in subsections (c) and (d).
(f) Upon request from the Department, a
				  project sponsor shall demonstrate that the underground retention times required
				  in this section are being met based on changes in hydrogeological or climatic
				  conditions since the most recent demonstration.
1. New
					 section filed 6-18-2014 as an emergency; operative 6-18-2014. Submitted to OAL
					 for filing and printing only. This adoption is not subject to OAL review and
					 shall remain in effect until revised by the Department of Public Health
					 pursuant to Water Code section
					 13562.5
					 (Register 2014, No. 25).
Note: Authority cited: Sections
						13521,
						13562 and
						13562.5, Water
						Code; and Sections
						131052
						and
						131200,
						Health and Safety Code. Reference: Sections
						13520,
						13522,
						13522.5,
						13523,
						13523.1,
						13524,
						13560,
						13561 and
						13562.5, Water
						Code.