Arsenic – Anthropogenic Sources Provision – Draft DEQ Proposed Approach
Goal: To ensure that the numeric criterion for water and fish ingestion, which is intended to account for natural conditions, does not unintentionally allow preventable human health risk from anthropogenic loading of arsenic from existing or new sources.
Purpose: DEQ is expecting to propose 2.7 µg/l for revised arsenic human health criteria for both fish ingestion only and water and fish ingestion. While the proposed numeric criteria for arsenic protect human health at an acceptable level given the presence of natural sources of arsenic in the state, it is the state’s policy to maintain the lowest added human health risk from anthropogenic sources of inorganic arsenic practicable, even when ambient inorganic arsenic concentrations are below the numeric criteria.
Scope: Sources adding inorganic arsenic to Oregon waters and thereby impacting a public drinking water supply.
Note: The organism only rate is based on a risk level of 10-6 and a FCR of 175, and is therefore very protective of human health. It is the water + organism criterion, for waters used both for fishing and for drinking water supply, where the criterion represents a higher risk level. Because the concern is with the drinking water exposure, the approach proposed below is focused on addressing sources that are impacting drinking water supplies.
Draft Proposed Rule Language:
340-041-0004
Antidegradation
(6) High Quality Waters Policy: Where the existing water quality meets or exceeds those levels necessary to support propagation of fish, shellfish, and wildlife and recreation in and on the water, and other designated beneficial uses, that level of water quality must be maintained and protected. However, the Environmental Quality Commission, after full satisfaction of the intergovernmental coordination and public participation provisions of the continuing planning process, and with full consideration of sections (2) and (9) of this rule, and 340-041-0007(4), may allow a lowering of water quality in these high quality waters if it finds:
(a) No other reasonable alternatives exist except to lower water quality; and
(b) The action is necessary and benefits of the lowered water quality outweigh the environmental costs of the reduced water quality. This evaluation will be conducted in accordance with DEQ's "Antidegradation Policy Implementation Internal Management Directive for NPDES Permits and section 401 water quality certifications," pages 27, and 33-39 (March 2001) incorporated herein by reference;
(c) All water quality standards will be met and beneficial uses protected; and
(d) Federal threatened and endangered aquatic species will not be adversely affected.
(7) Arsenic Reduction Policy: In order to maintain the lowest possible human health risk from arsenic, it is the policy of the Commission that the addition of inorganic arsenic from new or existing anthropogenic sources to waters of the state within a surface water drinking water source area be reduced to the maximum extent practicable. The requirements of this rule section [OAR 340-041-0004(7)] apply to sources that discharge to waters with an ambient inorganic arsenic concentration lower than the numeric inorganic arsenic criteria.
(a) The addition of arsenic from anthropogenic sources means arsenic mass added to the discharger’s wastewater through their process or activity and does not include arsenic mass that was taken into the facility from a surface water source.
(b) A surface water drinking water source area, for the purpose of this rule, means an area delineated by DEQ under the state’s drinking water protection program. The areas are delineated for the purpose of protecting public or community drinking water supplies that use surface water sources.
(c) For the first new permit or permit renewal application following the effective date of this rule, industrial dischargers located in a surface water drinking water source area and identified by DEQ as likely to contain arsenic in their wastewater will be required to collect and submit data to DEQ in order that DEQ may determine: 1) whether the source has the potential to increase inorganic arsenic concentrations in the public drinking water supply source water, and 2) whether the arsenic is added from anthropogenic sources.
(d) Where DEQ determines that both conditions in (b) are true, the source must develop an arsenic reduction plan and propose measures to reduce their inorganic arsenic loading to the receiving water. The proposed measures, monitoring and reporting requirements will be incorporated into the facility’s NPDES permit subject to DEQ review and public comment. In developing the plan, the source shall:
(i) Identify how much it can minimize its arsenic discharge through pollution prevention measures, process changes, wastewater treatment, alternative water supply (for groundwater users) or other possible pollution prevention and/or control measures;
(ii) Evaluate the costs, feasibility and environmental impacts of the potential arsenic reduction and control measures;
(iii) Estimate the reduced human health risk expected to result from the control measures;
(iv) Propose specific inorganic arsenic reduction or control measures, if feasible, and an implementation schedule; and
(v) Propose monitoring and reporting requirements that demonstrate progress in plan implementation and the arsenic load reductions that have resulted.
Proposed implementation approach: (We still need to sort out how much of this will be in rule versus an IMD, so the first step is to agree on the approach and how it would be applied. Then we will work on rule language and additional details.)
Note: We recognize that we do not yet have a QL for inorganic arsenic, but that will need to be developed as the numeric criteria are also for inorganic arsenic.
Point Sources – Industrial Sources:
Note: Technology-based permit requirements, the human health and aquatic life arsenic criteria and existing antidegradation policies will continue to apply as usual.
1. For the first new NPDES permit or permit renewal application submitted to DEQ after the effective date of this rule, all industrial dischargers required to submit arsenic data with their permit application and any additional industrial dischargers identified by DEQ (because their wastewater is likely to contain inorganic arsenic) that discharge to a water body within a drinking water protection area delineated by DEQ for a surface water intake, shall collect and submit with their permit application sufficient data to allow DEQ to make the determinations described in #3 below. This will include source water and effluent inorganic arsenic concentration and flow data and may also include ambient river data.
a. A discharger that has sufficient effluent data to demonstrate that its effluent concentration of inorganic arsenic is below DEQ’s quantitation limit or below the ambient river concentration immediately upstream of the discharge is exempt from the requirements of this rule.
2. DEQ will use the data to determine:
a. whether the discharger is adding a quantifiable load of inorganic arsenic to their wastewater (i.e. the concentration of inorganic arsenic in the discharge minus any inorganic arsenic load from intake water from a surface water source is greater than the QL); and
b. whether the added load is increasing the concentration of inorganic arsenic in a downstream public drinking water supply (DEQ will determine that a discharge has the potential to increase the concentration of inorganic arsenic in a downstream drinking water supply intake if the source increases the concentration of inorganic arsenic in the river after dilution (near field/point of discharge mixing analysis) by 10% or more, unless the source can demonstrate that their arsenic contribution will not affect a downstream water supply.)
c. Arsenic mass present in the facility’s intake water from a surface water source is not “anthropogenically added arsenic” for the purposes of this rule.
3. If the Department finds that the facility is adding inorganic arsenic and that the added load is impacting a public drinking water supply (both determinations under #3 above are true, the permittee shall develop an arsenic reduction plan, which will be incorporated into its NPDES permit subject to DEQ review and public comment. In this plan, the source will:
a. Identify how much it can minimize its arsenic discharge through pollution prevention measures, process changes, wastewater treatment, alternative water supply source or other possible pollution prevention and/or control measures;
b. Evaluate the costs, technical and economic feasibility and environmental impacts of the identified arsenic reduction and control measures; (Note 1: It is important to evaluate whether a potential arsenic reduction measure, such as a chemical substitution, represents an equal or worse environmental risk.) (Note 2: DEQ recognizes that evaluating water supply options and the environmental impacts of those is complex and there are many issues to consider other than the arsenic loading. If the source of arsenic is groundwater, there may be few if any feasible options for reduction.)
c. Estimate the reduced human health risk expected to result from the control measures;
d. Propose specific inorganic arsenic reduction or control measures, if feasible, and a schedule for implementing them; and
e. Specify monitoring and reporting requirements related to implementing the plan and the resulting effluent arsenic load reductions.
4. DEQ will identify factors that the permittee and the agency should consider in weighing the technical and economic feasibility of an inorganic arsenic reduction measure against the reduced human health risk that is expected to result and deciding which measures to implement.
5. If the timing of a permit renewal is such that the facility has not had sufficient time to collect the required data or develop an arsenic reduction plan prior to permit issuance, the permit will include the data collection and/or planning requirements and a reopener clause which will allow DEQ to incorporate the proposed plan/measures into the permit prior to the next renewal.
6. Arsenic reduction plans and their implementation will be reviewed at each permit renewal to evaluate progress in implementation and inorganic arsenic reductions and determine whether and new measures are feasible and/or proposed.
7. There are existing procedures for requesting the re-consideration of a permit that can be used by persons who have grounds to believe that either the data and analysis or the reduction measures included in the permit are inadequate.
Point sources – POTWs
1. Note: Technology-based permit requirements, the human health and aquatic life criteria and the antidegradation policies continue to apply.
2. All major POTWs are required to analyze their effluent for arsenic and submit that data to DEQ as part of their permit renewal application.
3. If Arsenic III (the primary inorganic from) remains on the Priority Persistent Pollutant list developed under SB737, DEQ will rely on the “737” process to address potential arsenic contributions from POTWs. Under “737,” the 52 largest POTWs, including all major municipal dischargers, will be required to test for arsenic III in their effluent. If the effluent concentration exceeds the trigger level specified in rule, the facility will be required to develop and implement a pollutant reduction plan for arsenic.
Point Sources – Other
1. Wood treating facilities – DEQ will incorporate the following into our renewal of industrial stormwater permits for wood treating facilities:
• Review data on arsenic levels in stormwater runoff
• Determine the sources of the arsenic on the site
• Require the facility to identify measures that could be taken to reduce arsenic loading, including chemical substitution, stormwater management and erosion control practices, stormwater treatment, soil testing and remediation, chemical storage and disposal practices, and others.
• Evaluate the measures, considering: a) potential for reduction of arsenic discharge, b) cost and c) potential environmental impacts (particularly for chemical substitutions), and incorporate appropriate measures into the permit.
3. Municipal stormwater management – DEQ will incorporate the following into our municipal stormwater permitting program:
• DEQ will review data on inorganic arsenic levels in stormwater runoff and/or UIC wells to determine whether municipal stormwater is a significant source of inorganic arsenic.
• If it is, DEQ will determine whether it is possible to identify the source(s) of the arsenic and whether additional measures or best management practices could be implemented that would reduce the arsenic loading.
Nonpoint Source Options:
1. Use the Toxics Reduction Strategy to evaluate whether the following actions would be: a) likely to reduce inorganic arsenic concentrations in surface water drinking water protection areas, or in waters that exceed the water quality criteria for arsenic, and b) cost effective:
• a limit on the amount of arsenic in fertilizers, pesticides and/or wood treating chemicals, or a ban on products containing arsenic if there are still such products in use;
• treated wood and/or chemical collection/take back programs,
• stormwater management in areas with large amounts of treated wood present, and/or
• enhanced erosion control practices on lands where soil inorganic arsenic levels are elevated .
2. Recommend that adequate control of runoff and erosion from urban development and agricultural lands be implemented for multiple benefits. One benefit would be to prevent arsenic and other toxic pollutants that adhere to soil particles from entering waterways. Some contaminants, such as arsenic, are no longer widely used, but may have built up in soils in certain locations from past use. In addition, such these controls would also reduce nutrient (i.e. phosphorus) and sediment loading from urban and agricultural lands and therefore provide multiple benefits to fish and aquatic life and the quality of Oregon waters.
3. Construction stormwater general permit. Erosion and stormwater control practices should be employed to reduce loading of sediment and chemicals attached to sediments to the stream.