Rhode Island Code of Regulations › Title 250 - Department of Environmental Management › Chapter 150 - Water Resources › Subchapter 10 - Wastewater And Storm Water › Part 6 - Rules Establishing Minimum Standards Relating to Location, Design, Construction and Maintenance of Onsite Wastewater Treatment Systems › Section 250-RICR-150-10-6.45 - Nitrogen Loading in Areas of Onsite Drinking Water Wells

Current through June 14, 2024
A. Applicability - For all OWTS applications
				  for New Building Construction and for Alterations to a Structure, the design
				  flow for an OWTS shall not exceed three hundred forty-five (345) gallons per
				  day per twenty thousand (20,000) square feet of applicant's lot area where the
				  property utilizing the OWTS or any adjacent lot is served by an onsite drinking
				  water well (public or private), or if there is a drinking water well within two
				  hundred feet (200') of the proposed OWTS, except as provided for below in
				  §§
										6.45(B) and
				  (C) of this Part. The Director may require
				  this standard to be met for OWTS Applications for Repair in areas where the
				  groundwater is shown to exceed the Preventive Action Limit for nitrate of five
				  (5) mg/l, pursuant to Subchapter 05 Part 3 of this Chapter, Groundwater Quality
				  Rules. The three hundred forty-five (345) gallons per day per twenty thousand
				  (20,000) square feet loading limitation is equivalent to approximately one
				  sixth of an acre (1/6) of applicant's lot area per bedroom. This rule applies
				  to all OWTS except those subject to the requirements of §
										6.39 of this Part.
				  Applicants must still meet all CRMC established density and other requirements
				  where applicable. Compliance with §
										6.45 of this Part does not
				  relieve applicants of the nitrogen reducing technology requirements in §
										6.43 of this
				  Part.
B. Design Flow Calculation -
				  The three hundred forty-five (345) gallons per day per twenty thousand (20,000)
				  square feet design limit may be exceeded for OWTSs utilizing nitrogen reducing
				  technology. The allowed design flow with a nitrogen reducing technology is
				  derived using the equation in §
										6.45(C) of
				  this Part or read from §
										6.45(D) of
				  this Part. For the purposes of §
										6.45 of this Part, there
				  are no limits on the design flow of OWTSs with nitrogen reducing technologies
				  that are approved by the Director as meeting the nitrogen standard of ten (10)
				  mg/l.
C. Nitrogen Loading
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D.
				  Nitrogen Loading
Nitrogen Removal (Percentage)
Effluent Nitrogen Concentration
								  (mg/l)
Maximum Design Flow per 20,000 sq. ft.
								  (gpd)
50
19
690
66
13
1015
75
10
1380
E.
				  Exceedance of Design Flow Calculation - The three hundred forty five (345)
				  gallons per day per twenty thousand (20,000) square feet design limit or other
				  design limit utilizing nitrogen reducing technologies pursuant to §
										6.45(B) of
				  this Part may be exceeded by the establishment of nitrogen credit land meeting
				  the requirements of §
										6.45(F) of
				  this Part under the following circumstances:
1. For subdivisions - The design limit must
				  be met over the entire area of the subdivision. This can be met by designating
				  portions of the subdivision as nitrogen credit land.
2. For individual lots - The design limit can
				  be calculated by establishing adjacent properties as nitrogen credit land with
				  the consent of the property owner.