Technical Guidance #6 Water Use Determination

1. Technical Guidance #6Water Use Determination GeoEnvirologic Professional Development Workshop February 18, 2011 Lavinia Zanini

2. WaterUse Determination Overview: • What is TG6? Review. • How do we apply TG6 to determine water uses at contaminated sites? Quiz. • How do we remediate contaminated sites under TG6? Policy direction. Land Remediation Section – Environmental Management Branch

3. Water Use Determination Purpose: • To recognize that groundwater is a valuable crown owned resource that should be protected and remediated for future use. • Provide clear reasoning and direction with respect to establishing groundwater use at a site. Land Remediation Section – Environmental Management Branch

4. Water Use Determination • There are four water uses defined in the Contaminated Sites Regulation for groundwater: • Drinking • Aquatic Life • Irrigation • Livestock • TG6 helps the practitioner decide which water use will apply at a site, or even if “no water use” applies. • Groundwater standards for remediation are based on water use at a site. Land Remediation Section – Environmental Management Branch

5. Water Use Determination: Current and Future DW Land Remediation Section – Environmental Management Branch

6. Water Use Determination: Current DW Q 1. Is the water currently used for drinking? • Based on receptors in area of site. • 500 m distance to receptor. • Consideration up-gradient or downgradient of source. • Guidance for types of searches. Land Remediation Section – Environmental Management Branch

7. Water Use Determination: Future DW Q 2. Does the geological unit have a hydraulic conductivity less than or equal to 1 x 10-6 m/s and a yield less than 1.3 L/min? • Can the geological unit yield enough water to supply a single family dwelling? • Unconfined aquifers that are seasonal or <1 m saturated thickness exempt. • Example yield calculation provided. Land Remediation Section – Environmental Management Branch

8. Water Use Determination: Future DW Q 3. Is the natural quality of the water such that it is unsuitable for drinking water? • Equal to or greater than 4,000 mg/L TDS is considered unsuitable for DW purposes. • Water in organic soils (like muskeg). Land Remediation Section – Environmental Management Branch

9. Water Use Determination: Future DW Q 4. Is their a confining geological unit that protects the aquifer ? • Differing water uses may apply for units overlying a deeper drinking water aquifer if a natural confining geological unit exists to protect the deeper aquifer. • the natural confining unit must: • be greater than or equal to 5 metres thick; • have a bulk hydraulic conductivity that is less than or equal to 1 x 10-7 m/s; • be relatively uniform and free of fractures; and • is continuous across the extent and predicted migration of the shallow subsurface contamination. Land Remediation Section – Environmental Management Branch

11. Water Use Determination: Aquatic Life (AW) • Aquatic life groundwater use applies to all land located within 500 metres from a surface water body containing aquatic life. • Aquatic life water use applies at sites where there is the potential for contaminated groundwater to flow through preferential corridors that discharge directly to a surface water body containing aquatic life. AW 500 m AW Land Remediation Section – Environmental Management Branch

12. Water Use Determination: Irrigation (IW) and Livestock (LW) Watering IW and LW uses apply when: • A site is considered agricultural land use or is within a provincial Agricultural Land Reserve (ALR). • Irrigation or livestock watering wells are within a distance of 500 metres down-gradient or 100 m up-gradient of a groundwater contamination source. IW and LW do not apply when K<10-6 m/s Land Remediation Section – Environmental Management Branch

13. Water Use Determination: No Water Use “No Water Use” applies when: • None of the water uses (drinking, aquatic, irrigation or livestock) apply based on assessment of water use under TG6. Land Remediation Section – Environmental Management Branch

14. Water Use Determination: Interpretation How do we apply TG6 to determine water uses at contaminated sites? Examples from stakeholders Land Remediation Section – Environmental Management Branch

15. Water Use Determination: Interpretation 10-8 m/s NO DW DW 5 m DW 10-4 m/s Land Remediation Section – Environmental Management Branch

16. Water Use Determination: Interpretation DW <1 m 10-4 m/s 10-8 m/s DW 2 m DW

17. Water Use Determination: Interpretation 300 m downgradient NO DW <1 m 10-4 m/s 6 m 10-8 m/s DW DW

18. Water Use Determination: Interpretation DW DW 70 m 10-7 m/s to 10-6 m/s DW

19. Water Use Determination: Interpretation aquifer <4,000 mg/L TDS DW AW >4,000 mg/L TDS NO DW

20. Water Use Determination: Interpretation NO DW DW <1 m 10-7 m/s 5 m aquifer <4,000 mg/L TDS DW >4,000 mg/L TDS NO DW

21. Water Use Determination: Interpretation DW 10-5 m/s

22. Water Use Determination: Interpretation DW 10-5 m/s

23. Water Use Determination: Interpretation NO IW and LW 10-7 m/s NO IW and LW 5 m DW IW and LW 10-5 m/s DW

24. Water Use Determination: Interpretation ????? <1 m 10-7 m/s NO IW and LW 5 m IW and LW 10-5 m/s

25. Water Use Determination: Interpretation If drinking water use applies at a site, should it be assessed against both water and soil drinking water protective standards? Yes. There are sites with groundwater which is not considered potable due to high concentrations of dissolved solids that occur naturally. Does DW apply? Yes. Land Remediation Section – Environmental Management Branch

26. Water Use Determination: Interpretation Are NOMs required? Yes. When are NOMs required? • If a site investigation is underway. • If independent remediation is underway. • If vapour, groundwater or surface water monitoring are ongoing as part of an ongoing site investigation or ongoing independent remediation at a site (e.g. as in the case of confirmatory monitoring of remediation). When are NOMs not required? • A NOM is not required on the basis of historical analytical data where site investigations or independent remediation were completed in the past and are not ongoing. Land Remediation Section – Environmental Management Branch

27. Water Use Determination: Remediation How do we remediate contaminated sites under TG6? New policy direction. Land Remediation Section – Environmental Management Branch

28. Water Use Determination: Remediation Under new Technical Guidance 6 can a risk-based Certificate of Compliance be obtained for a site where future drinking water use applies but there is no current use of water for drinking purposes? Yes. Where future drinking water use has been determined to apply at a site but there is no current drinking water use, risk-based Certificates of Compliance can be obtained. Schedule B clauses in these certificates normally would include restrictions on water use, monitoring requirements and may include other conditions depending on site circumstances. (from Q and A) Land Remediation Section – Environmental Management Branch

29. Water Use Determination: Remediation Policy Direction – Compliance Point Sources of soil and groundwater contamination should be controlled or removed to the maximum extent practicable such that contamination that has migrated beyond a site boundary meets applicable DW numerical standards within a “reasonable time frame”. Groundwater monitoring will be required, as appropriate to site circumstances, to demonstrate achievement of remediation standards. Land Remediation Section – Environmental Management Branch

30. Water Use Determination: Remediation

31. Water Use Determination Questions? website: http://www.env.gov.bc.ca/epd/remediation/guidance/index.htm#tech E-mail: Lavinia.zanini@gov.bc.ca