LIABILITY MANAGEMENT AT HIGHWAY MAINTENANCE YARDS. Tri-Party Conference March 13/14, 2017 Scott Digel

Transcription

1 LIABILITY MANAGEMENT AT HIGHWAY MAINTENANCE YARDS Tri-Party Conference March 13/14, 2017 Scott Digel

2 Outline Alberta Regulatory Environment Typical Issues at Highway Maintenance Sites Determination and Management of Environmental Liabilities

3 Contaminated Sites Area where a substance is present that may cause, is causing, or has caused a significant adverse effect In practice: chemical concentrations above guideline levels

4 Regulatory Expectations for Contaminated Sites Risk-based response Ultimate goal is prevention of adverse effects Avoid do nothing approach Plan for eventual remediation Preferably within 5-10 years

5 Implementation Framework Tiered management framework 1: Apply generic guidelines 2: Limited site-specific adjustment 3: Site-specific risk assessment Same human and environmental health endpoints at all tiers

6 Alberta Framework Tier 1 Generic numerical guideline values Tier 2 Limited site-specific modification of generic guideline values or derivation of site-specific objectives Exposure Control Site specific risk assessment and risk management (formerly Tier 3)

7 Typical Issues At Highway Yards Previous salt storage practices Salty water run-off and infiltration Soil and groundwater contamination Salt properties It doesn t biodegrade and it travels as quickly as groundwater It can affect plant growth, drinking water and aquatic life

8 Liability Determination Phase I and Phase II ESA Selection of applicable soil and groundwater guidelines Use guidelines to determine nature and extent of contamination in soil and groundwater Liability = Cost to remediate the contamination Key Point Extent of contamination depends on the soil & groundwater guidelines used.

9 Soil & Groundwater Guidelines There is some flexibility in determining the guidelines that can be applied Tier 1 guidelines are designed to be protective in the large majority of cases Easy and low cost to determine and apply Tier 2 guidelines are more representative of actual site conditions Increased data requirements and cost to determine Usually less conservative than Tier 1, resulting in smaller extents of impact

10 What Can Be Done? Develop Site-Specific Tier 2 Soil and Groundwater Guidelines for Salt Tier 1 Liability Tier 2 Liability

11 What about Complex Sites? Use a defensible and affordable sitespecific approach for large or complex sites Make sure that the Regulator knows and understands the approach

12 The Process How can we best identify remediation and risk management required to protect relevant receptors? Initial considerations: Solute plumes are not homogenous blocks Trace migration moving forward Make it truly site-specific and avoid blanket assumptions Make it quick, accurate and affordable

13 Reality Check What if my salt plume doesn t look like this but looks more like this?

14 Reality Check (cont d) Three-dimensional input of concentration data Clear visualization of hot spots via layering

15 Targeted Remediation Targeted removal of chloride hotspots

16 Real-World Outcome Initial Mass of Chloride Present Remedial guideline for excavation area Mass of chloride to be removed Comparison of Standard and Targeted Approaches Standard 186,600 kg Targeted 390 mg/kg Hot Spot Removal 177,567 kg 5,640 kg Soil to be removed 86,737 m 3 1,630 m 3

17 Managing Multiple Sites? A site sensitivity assessment can be used to rank a portfolio of sites from a sensitivity standpoint by evaluating: Source characteristics Receptor types and proximity Site geology and hydrogeology Provides a consistent framework to prioritize and communicate (internally and externally) the work being done

18 Thank You!