Point of intake methods

Transcription

1 Point of intake methods Problem: Positional data for water supply system intakes is restricted information. However the arsenic and nitrate standards apply at point of intake (1,2). In an effort to make the303(d) Listing Methodology as transparent as possible, the Water Quality Control Division (Division) is proposing to add a assessment method for these two parameters so that outside stakeholders can reach conclusions in the same manner as the Division. To address this issue we looked at the work already performed by a collaborative effort between the Colorado Deprtment of Public Health and Environment (CDPHE) and the COGCC to address a similar problem (6). The Source Water Protection Program (SWAP) developed spatial coverages of surface water supply areas (5) where special precautions would need to be taken by the oil and gas industry, because if a release happened it potently could affect a water supply intake without enough time to respond effectively (7). With average statewide flows a 5 mile distance represents a 6 8 hour latency to point of intake. Another reason, the 5 mile upstream protection distance was implemented was because of State Revised Statue (4). Municipal utilities. This statute allows for controls to be placed protecting the water from pollution for five miles above the point from which it is taken. It was decided in order to avoid picking an arbitrary distance, to use information currently publicly available, and that could be representative of the point of intake we consider any data gathered in the surface water supply areas as representative of the point of intake. Proposed Listing Methodology: p.24 d. Water Supply Use based Standards Nitrate/Nitrite and Arsenic: Assessment of nitrate and/or nitrite, and arsenic Drinking Water Supply Use based standards will consider the combined total or individual ambient concentrations at the point of intake to a domestic water supply. Data located within the surface water supply areas, as defined by New Rules and Amendments to Current Rules of the Colorado Oil and Gas, will be considered representative of the point of intake. Surface Water Supply Area is defined as classified water supply segments within five (5) stream miles upstream of a surface water intake on a classified water supply segment. Exceedences of nitrite and/or nitrate, and arsenic standards, if at locations other than the point of intake outside of the surface water supply area in a segment, may lead to inclusion of the segment on the M&E List. Where a range is specified for the arsenic standard water bodies will be considered in attainment of this standard, and not included on the Section 303(d) List, so long as the existing ambient quality does not exceed the second number in the range.

2 To download a Coverage of statewide Surface water supply areas by the COGCC: To view a online map of surface water supply areas at the COGCC site:

3 References The Basic Standards And Methodologies For Surface Water (5 CCR ) (effective 1/1/2011) STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; June 2005 Rulemaking Hearing; Final Action August 8, 2005; Revisions Effective December 31, 2005 and December 31, 2007 P173. Arsenic : Water bodies will be considered in attainment of this standard, and not included on the Section 303(d) List, so long as the existing ambient quality does not exceed the second number in the range. The Drinking Water Supply table values are applicable at the point of intake to a domestic water supply. The Basic Standards And Methodologies For Surface Water (5 CCR ) (effective 1/1/2011) STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; JUNE 7 8, 2010 RULEMAKING; FINAL ACTION AUGUST 9, 2010; EFFECTIVE DATE JANUARY 1, P 194. G. Point of Water Supply Intake Implementation The Commission clarified how the domestic water supply standards for arsenic and nitrate would be implemented in permits by expanding on the Table II footnote 4 (nitrate) and Table III footnote 14 (arsenic). These two standards apply at the point of water supply intake. In order to provide a consistent level of protection and simplify implementation in the CDPS permitting process, the default assumption will be that the standard is applied at the end of the applicable regulatory mixing zone. This presumption can be overcome if the permittee provides information demonstrating 1) that there is no actual domestic water supply use; or 2) that the standard will not be exceeded at the point of intake Primary Drinking Water Regulations 5 CCR (amended 8/9/10, effective 11/30/10) Definitions p. 10 (101) Plant intake refers to the works or structures at the head of a conduit through which water is diverted from a source (e.g., river or lake) into the treatment plant.

4 State Revised Statute ( (IV)(b) 1975) Municipal utilities. (IV)(b) To construct or authorize the construction of such waterworks without their limits and, for the purpose of maintaining and protecting the same from injury and the water from pollution, their jurisdiction shall extend over the territory occupied by such works and all reservoirs, streams, trenches, pipes, and drains used in and necessary for the construction, maintenance, and operation of the same and over the stream or source from which the water is taken for five miles above the point from which it is taken and to enact all ordinances and regulations necessary to carry the power conferred in this paragraph (b) into effect; New Rules and Amendments to Current Rules of the Colorado Oil and Gas 100. definitions SURFACE WATER SUPPLY AREA shall mean the classified water supply segments within five (5) stream miles upstream of a surface water intake on a classified water supply segment. Surface Water Supply Areas shall be identified on the Public Water System Surface Water Supply Area Map or through use of the Public Water System Surface Water Supply Area Applicability Determination Tool described in Rule 317B.b. CLASSIFIED WATER SUPPLY SEGMENT shall mean perennial or intermittent streams, which are surface waters classified as being suitable or intended to become suitable for potable water supplies by the Colorado Water Quality Control Commission, pursuant to the Basic Standards and Methodologies for Surface Water Regulations (5 C.C.R ). New Rules and Amendments to Current Rules of the Colorado Oil and Gas 6. Statement of basis and purpose: (P 11.) 6. Classified Water Supply Segment: Basis: This statutory basis for this addition is section (11)(a)(II), C.RS. Purpose: Rule 317B is a new rule for protecting public drinking water systems. This definition was added to establish the scope of this rule. It creates the basis for protection zones that, when combined with performance requirements applicable within certain distances of classified water supply segments, will ensure adequate protection of public drinking water supplies.

5 New Rules and Amendments to Current Rules of the Colorado Oil and Gas Statement of basis and purpose: (P32.) 1. Rule 317B., PUBLIC WATER SYSTEM PROTECTIONS 7. Basis: The statutory bases for this rule are sections and , C.R.S. Purpose: In adopting this new rule, the Commission s primary objective was to minimize the potential for accidental contamination, including from sedimentation or chemicals, of public drinking water supplies due to oil and gas operations in Colorado. The first opportunity for protecting drinking water supplies is to protect the source water itself. As such, the Commission decided that, as a matter of policy, adequate protection of public drinking water supplies requires the creation of protection zones combined with performance requirements applicable within certain distances of classified water supply segments. To clarify and support this policy approach, the Commission established several new definitions, including those for: Classified Water Supply Segment, Ordinary High Water Line, Public Water System, Surface Water Intake, Surface Water Supply Area, Drilling Completion Production and Storage (DCPS) Operations, Non Exempt Linear Feature, Existing Oil and Gas Location, New Oil and Gas Location and New Surface Disturbance. This policy approach was supported by a number of parties and public comments. The approach to protecting public drinking water reflected in the rules adopted by the Commission includes establishment of an Internal Buffer Zone, applicable to Drilling, Completion, Production, and Storage ( DCPS ) Operations located within 300 feet of a Classified Water Supply Segment. This most protective zone serves essentially as a drilling exclusion zone or setback, unless an operator satisfies the stated variance criteria, which include offering substantially equivalent protection of drinking water quality (see below). The premise for establishing this zone is that a significant release in these areas would likely contaminate surface water used as drinking water source quickly, thereby not allowing the public water system, the oil and gas operator, nor the COGCC enough time to respond effectively to protect the public water system. Section 303(d) Listing Methodology 2010 Listing Cycle: 8. (p.24) d. Water Supply Use based Standards Nitrate/Nitrite and Arsenic: Assessment of nitrate and/or nitrite, and arsenic Drinking Water Supply Use based standards will consider the combined total or individual ambient concentrations at the point of intake to a domestic water supply. Exceedences of nitrite and/or nitrate, and arsenic standards, if at locations other than the point of intake in a segment, may lead to inclusion of the segment on the M&E List.