Presentation on theme: "PHASE II ESA INVESTIGATING IDENTIFIED CONCERNS. PHASE II ESA Why do we do it? To provide information relevant to: ＞ Assessing whether there has been a."— Presentation transcript:
PHASE II ESA Why do we do it? To provide information relevant to: ＞ Assessing whether there has been a release ＞ Meeting continuing obligations of landowner under CERCLA liability defenses ＞ Qualifying for a brownfields remediation grant ＞ Identifying, defining and evaluating property conditions associated with target analytes that could present a risk to human health or the environment and therefore result in potential liability ＞ Allocating business environmental risk ＞ Supporting liability disclosures
PHASE II ESA How do we do it? ＞ ASTM E 1903-11 for most initial investigations ＞ Can also be informed by multiple agency and regulatory program standards, e.g.: OEPA Voluntary Action Program (VAP) RCRA Corrective Action CERCLA Site Assessment
PHASE II ESA: CONCEPTUAL SITE MODEL ASTM Definition: ＞ A representation of hypothesized current site conditions, which describes the physical setting characteristics of a site and the likely distribution of target analytes that might have resulted from a known or likely release, and which is based on all reasonably ascertainable information relevant to the objectives of the investigation and the professional judgment of the Phase II Assessor.
PHASE II ESA: CONCEPTUAL SITE MODEL What do we know or suspect through our observations and data sources? ＞ Site buildings, site and nearby soils, groundwater and bedrock ＞ Suspected or known releases And what do we need to investigate as a result? ＞ Confirm presence or absence of releases ＞ Define risks to human health and the environment
1928 Sanborn: auto-related uses and buried canal nearby
PHASE II ESA: CONCEPTUAL SITE MODEL What do we know or suspect? ＞ Historical filling station, southwest corner ＞ Historical underground tanks north of northeast buildings ＞ Historical auto-related uses ＞ Damaged drums near surface drain on northwest building corner ＞ Possible solvent and/or petroleum use in workshop across street ＞ There also were additional garages and filling stations in the surrounding area
PHASE II ESA: CONCEPTUAL SITE MODEL More of what we know or suspect ＞ Groundwater projected to flow toward the Tuscarawas River, located approximately 1,000 feet west of the site, BUT ＞ Former Miami & Erie Canal located under 1 st Street SW – could complicate near-surface flow patterns ＞ Hydrogeological sources predict sandy loam surface soils over sand and gravel aquifer, but surface soils were likely altered by the past development and subsequent demolition
PHASE II ESA: CONCEPTUAL SITE MODEL What do we need to investigate as a result? ＞ Are tanks or tank piping still present? ＞ Did the drums near the surface drain cause a release into soils around the underground drain piping? ＞ Did the auto-related activities on the site and in the area result in contamination at the site? ＞ Where (depth, formation) is groundwater and which way is it moving?
PHASE II ESA: CONCEPTUAL SITE MODEL Always check for existing data! ＞ OEPA files ＞ BUSTR files ＞ Health Department records of wells, septic systems, etc. Why spend the money to repeat investigations someone else has already done? Use existing data to refine the site conceptual model.
PHASE II ESA: INVESTIGATIVE METHODS Investigation methods can be divided into: ＞ Direct observation and sampling vs. remote sensing ＞ Aboveground vs. subsurface In general, lower disturbance (of soil or building materials) and simpler technology equals lower cost
PHASE II ESA: INVESTIGATIVE METHODS Aboveground, direct observation and sampling: ＞ Surface soils, surface water, sediments ＞ Indoor air ＞ Outdoor air (much less commonly used) Target analytes (suspected contaminants) drive analytical methods, which are the main cost driver
PHASE II ESA: INVESTIGATIVE METHODS Aboveground, remote sensing METHODDETECTSLIMITATIONS Magnetometer Buried metal (tanks, drums, piping) Depth, surface metal or rebar interference Ground-penetrating radar (GPR) Changes in density, texture (buried materials, voids) Clay soils, damp soils, high subsurface variability Seismic reflectionChanges in density Natural & man-made noise (traffic, etc.)
PHASE II ESA: INVESTIGATIVE METHODS Subsurface, remote sensing ＞ Many instruments have modified versions that can be used in a soil boring or monitoring well: Dissolved oxygen, temperature, pH, conductivity Flow (groundwater can flow up and down in an aquifer as well as sideways) Seismic reflection/penetration
PHASE II ESA: INVESTIGATIVE METHODS Subsurface, direct observation and sampling: ＞ Test pits ＞ Soil borings – hydraulic push, hollow-stem auger, air rotary, hydrosonic, cable tool ＞ Groundwater wells – temporary vs. permanent, bailers vs. pumps vs. passive samplers ＞ Soil gas
PHASE II ESA: INVESTIGATIVE METHODS Remember: the driller’s and sampler’s technique will have a large effect on the usefulness of the information collected and the validity of the samples.
PHASE II ESA: FIELD INVESTIGATIONS Questions to remember in talking to the consultant: ＞ What will we know if the tests are positive? ＞ What will we know if the tests are negative? ＞ Will we have defined the site and the concerns well enough to meet our objectives? (Make sure objectives are clear!) Field investigation may require multiple phases to meet the objectives, depending on what they are.
“PHASE III ESA” – RISK AND REMEDIATION To address concerns identified for a site: ＞ Know the properties of the contaminants ＞ Understand the ways in which those contaminants might affect property users, the environment and continuing obligations under CERCLA defenses or other regulatory programs ＞ Limit exposure by removing, treating in place or blocking/ redirecting the contaminants
“PHASE III ESA” – RISK AND REMEDIATION Exposure ＞ Humans exposed through: Ingestion Inhalation Absorption (and skin injury) ＞ Impacts to ecological resources Plants Animals/birds/insects Fish/aquatic species Media ＞ Contamination can be found in: Soil Groundwater Surface water, sediments Indoor/outdoor air Building materials Consumer goods Plant matter/living tissue
“PHASE III ESA” – RISK AND REMEDIATION Migration ＞ Solids can be blown, tracked, deposited and hauled, and can dissolve, float or sink or be suspended in liquids ＞ Liquids can flow, float, sink, percolate through, be absorbed by and evaporate ＞ Gases can diffuse in open air and through cracks and porous materials, including soil, and can dissolve into liquids
“PHASE III ESA” – RISK AND REMEDIATION At the case study site: magnetic survey found former filling station piping; possible tanks under sidewalk addressed during demolition/construction ＞ Soil and groundwater sampling in the vicinity of piping did not show contaminants, so no remediation was needed ＞ No tanks or contaminants were found beneath the sidewalk north of the F.O.E. building during demolition
“PHASE III ESA” – RISK AND REMEDIATION At the case study site: semi-volatile organic compounds and buried building materials found in former garage location ＞ Building materials removed to prepare site for redevelopment ＞ Contaminants detected at low levels and well below the ground surface – no significant vapors expected and with the building over the area, the soils will not be excavated and rainwater will not percolate through. No other mitigation was needed.
“PHASE III ESA” – RISK AND REMEDIATION Risk assessment ＞ Define concentrations of contaminants ＞ Evaluate exposure pathways to determine which are complete For example, volatile contaminant in soil travels as gas through soil formation and building foundation to indoor air ＞ Could the known contaminant concentrations cause an unacceptable risk to human health or the environment? 1 in 1,000,000 vs. 1 in 100,000
“PHASE III ESA” – RISK AND REMEDIATION Screening levels and action levels ＞ Developed by making assumptions about typical conditions, then calculating the concentration of a contaminant that is the threshold for risk ＞ If exceed screening levels, either move to more site-specific evaluation or take remedial action ＞ Action levels are specific to regulatory programs; exceeding them results in prescribed actions
“PHASE III ESA” – RISK AND REMEDIATION At the case study site: groundwater contaminated with volatile organic compounds (solvents) ＞ Not drinking water, no plans to use for irrigation ＞ Concern over vapor diffusion through ground and into building addressed through passive sub-slab vapor removal system (“radon system”) and post-construction indoor air sampling to confirm that active removal was not needed
“PHASE III ESA” – RISK AND REMEDIATION At the case study site: Arsenic was detected in two soil samples on the north part of the site at unacceptable levels ＞ Surface soils removed and replaced; adequate removal confirmed by sampling the edges of the excavation ＞ Some soils allowed to remain in place under building and pavement; a maintenance plan and deed restriction were put in place to ensure future maintenance of these controls
Soil arsenic discovered as a result of the soil borings and removed or covered with clean soils during construction
“PHASE III ESA” – RISK AND REMEDIATION Arsenic and naturally occurring chemicals of concern ＞ Arsenic is naturally occurring mineral, but can cause cancer at low levels and is a poison at much higher concentrations ＞ If levels are naturally occurring, then remediation is not required ＞ Natural levels are location-specific; determine through sampling an undisturbed nearby location ＞ Alternative: published area-specific surveys or the USGS National Geochemical Survey, which provides county-level data
“PHASE III ESA” – RISK AND REMEDIATION Recap: remediation and mitigation ＞ Basically three options: remove, prevent contact or treat in place ＞ Always have: Scientifically supportable and measurable endpoint Means of verifying that the approach is working ＞ If preventing contact, also have a plan to ensure maintenance of the solution: deed restriction, O&M plan, tenant notification, etc.