Beyond Data 2 Combined Files (1)

20250305 01 - SEIMA Introduction-Mar2025 - Rev (1).pdf 20250305 02 - SEIMA Import of CSM-Mar 2025 - Rev (1).pdf 20250305 03 - SEIMA Feel The Fear -Mar 2025 - Rev.pdf 20250305 04 - SEIMA Building A Basic CSM -Mar 2025 - Rev.pdf 20250305 05 - SEIMA Exercise 1 Lets sketch a CSM rev.pdf 20250305 06 - SEIMA Remediation and the CSM -Mar 2025 - Rev.pdf 20250305 07 - SEIMA Exercise 2 Initial Options rev.pdf 20250305 08 - SEIMA Mind the Gaps -Mar 2025 - Rev.pdf 20250305 09 - SEIMA Exercise 3 Picking a Horse rev.pdf 20250305 10 - SEIMA Wrap Up - Mar2025 - Rev (1).pdf 1 Beyond Data - Part 2 Conceptual Site Models for Effective Remediation and Risk Management Guy Patrick & Pete Craig March 19, 2025 Saskatoon 2 About This Course Introductions, Objectives and Outcomes Beyond Data – Part 2 3 Be better equipped to develop a Conceptual Site Model for any site Understand subsurface behaviours of both common and unusual site contaminants Systematically consider a full range of risk management options Know how to use your Conceptual Site Model to: Link with effective remediation strategies Optimize characterization efforts to avoid critical data gaps Select risk management and remediation measures that avoid costly re-work and failed projects Overall Course Objectives At the end of this course, you will: 4 8:00 – 8:20 Introductions 8:20 – 8:50 Why Conceptual Site Models Matter 8:50 – 9:10 Remediation Needs a Solid CSM 9:10 – 9:45 Building a Basic CSM 9:45 - 10:05 Exercise #1 – The Site 10:05 – 10:20 Break (15 Minutes) 10:20 – 10:50 Remediation and the CSM 10:50 – 11:10 Exercise #2 – The Options 11:10 – 11:55 Mind the (Data) Gap 11:55 – 12:15 Exercise #3 – The Recommendation 12:15 – 12:45 Wrap-Up and Lunch Course Agenda 5 Let’s Interact – Poll Everywhere 11 Our Experience – and Our Aspirations for Working With You Instructor: Guy Patrick, M.Sc., P.Eng., CSAP [email protected] (604) 219-8437 Volunteer Facilitators: Pete Craig, M.Sc., PChem ([email protected] ) Eric Cowan B.A.S., C.E.T. ([email protected] ) 12 A Word About Course Materials PDFs We will use these during class exercises You will be asked to electronically draw or sketch on these, or use the hard copy provided! Hard Copies (Your Option) There are hard copies of two exercises provided You may wish to print hard copies of PDFs The “Reading List” Running list of key references, many available at low to no cost. Comments and additions back to Guy & Pete Putting Training Into Context Putting Training Into Context 14 Introductions, Objectives and Outcomes End 1 What is a Conceptual Site Model?? Why Do They Matter?? 1 2 Guy’s Early Days: (plus ça change, plus c'est la même chose) 1981 – Bulk Jet Fuel Spill, Regina Airport - Over 20,000 L of jet fuel released but contained in bermed area. No worries !?! •API modeling predicted penetration to 6 m (20’) max. •But fuel *actually* penetrated into fractured clay •Remediated by excavation to 6 m depth, land farming (ex situ bio), and backfilling •Site restored with expressway 3 •Where is the contamination? How far does it go? How deep? •Is the contamination moving/spreading? •How did the contamination get there? Do I really know all of the relevant site history and sources? •How well do I know the contaminants and their behaviour in the ground? •Are the regulations and acceptable regulatory approaches clear or likely to change? •Do I have enough information to adequately understand actual risks to human health or the environment? •Do I know the site conditions well enough for successful design of a remediation system? •Do I have the right expertise on my team? Examples of Some Key Uncertainties In the Contaminated Sites World 4 “A conceptual site model is a three- dimensional picture of site conditions that conveys what is known or suspected about the sources, releases and release mechanisms, contaminant fate and transport, exposure pathways, potential receptors, and risks. The conceptual site model is based on the information available at any given point in time and will evolve as more information becomes available .” – US EPA What is a Conceptual Site Model? Note: “picture” doesn’t just mean a drawing...it’s the entire “narrative.” 5 Integrated CSM and Conceptual Exposure Model (CEM) 5 6 CSM Vapour Focus 7 Why do we need a Conceptual Site Model? A CSM is the necessary base for any remedial design or risk management “know what you are dealing with before you try to fix it!” CSMs are usually simple and made to be understood CSMs allow you to explain complex problems, dividing them into pieces CSMs can/should be checked and updated with any new information CSMs are cool and stimulate discussion Risk Management options demand a CSM that stands the test of time A good CSM is a perfect tool for communication Pers comm. Jean-Pierre Davit 8 An Inference Model with Crucial Predictive Value Extent? Risk? Well Spacing? 9 Site Characterization Problems 9 Adapted from R. Beckie, UBC 10 Remediation Success & Site Closure Depend on the Conceptual Site Model Soil properties, depth, geochemistry? Anticipated Efficacy? Interferences? Cost? Sustainability? Side effects? Access? Other uses? Sample where? Looking for what? What are the decision rules? COCs, concentrations, basic media properties? What, Where, In What Context, When? Stability? Seasonality? Attenuation? Iteratively refined to be fit for purpose at each stage in the journey to closure 11 CSMs, Risk and Remediation Suthersan, In Situ Remediation From CSM ITRC (https://ois-isrp-1.itrcweb.org/3-amendment-dose-and-delivery-design/#3_8_1) 12 12 In the contaminated sites world, the Conceptual Site Model (“CSM”) provides the framework for success all the way to closure! 13 CSMs evolve as we gain more information 13 14 Example Preliminary CSM 14 EPA 542-F-11-011 July 2011 15 Example Detailed Characterization CSM 15 EPA 542-F-11-011 July 2011 16 Example Remediation/Risk Management CSM 16 Modified from EPA 542-F-11-011 July 2011 Hotspot Excavation •Street stability •Water management •Utilities adjacent to roadway Vapour Management Systems •Radius of influence, flowrates, concentrations •Interface with foundations, slabs and u/g services Seepage Mitigation •Injected reactive barrier? •Natural Attenuation? •Mats? •Physical cut-off? Residual Source Control ISCO? Free-Phase Extraction? Hydraulic containment? Physical containment? S/s? 1 Let’s look at some consequences of an inadequate CSM What do you notice? What was missing from the CSM? How could this have been avoided? 2 Real Consequences of Bad CSMs 3 3 Feel the Fear SURPRISE!!! 4 EPA/625/R-95/005 (1996) Dead on Arrival – Pumping Clean Sand 5 U.S. EPA (2002) Groundwater Remedies Selected at Superfund Sites. Report No. EPA-542-R-01-022. Wasted Decade? 6 350 Ellis Street, Mountain View California (1987) Circa 1987 7 350 Ellis Street, Mountain View California (1987) More than a few pore volumes of water: •100-ft deep soil + bentonite (clay) cut-off wall •AND Pump-and-treat •AND SVE •Now in 4 th decade “In 2022, the treatment system treated approximately 11.2 million gallons of water and removed approximately 296 pounds of VOCs ... Approximately 20,200 pounds of VOCs have been treated from 1986 through the end of 2022...” – 2022 Annual Progress Report 2010 secant pile seepage cut-off wall (drilled from surface) to bedrock to allow excavation without dewatering the Pacific Ocean... ...“bedrock” in the characterization drilling logs turned out to be mostly boulders (water flows around boulders.) 2016 Shallow Soil Mixing (SSM) drill attempts buried timber mixing Deep Soil Mixing (DSM) wall finds a bedrock “canyon” where the wall base should key in 11 Installing Waterloo Barrier (A Certified Seal) Waterloo Barrier Wall installation through sand fill adjacent to rock fill containment berm. This contractor is injecting H 2 O 2 , a chemical oxidant, to remediate a chlorinated solvent... ...the H 2 O 2 was consumed oxidizing natural organic material... ...and turning lower solubility chromium (III) to more mobile chromium (VI) - “hex chrome”. The groundwater literally turned yellow-green. Zero Valent Iron works best... ...when the injected particle size and injector configuration match the formation (2004). 14 The following conclusions were derived for the 68 PRBs where reviewable site data were readily available [2005]: •90% of the sites are reportedly meeting regulatory objectives •6% of the sites had hydraulic issues that have required system expansion (additional iron to address incomplete plume capture) or were related to construction artefacts •4% of the sites implemented pump and treat alternatives to ensure capture of the portion of the plume bypassing the PRB. ...To date, no ZVI PRB has required rejuvenation due to hydraulic plugging or loss of reactivity due to precipitate formation. In most environments, ZVI PRBs are expected to last at least 15 years before refurbishment or replacement is considered....However, for the 10% of the PRBs with relatively poor performance, it is apparent that hydraulic issues (rather than geochemical) have been the primary cause. Potential problems include unrecognised variability in plume dimensions, groundwater flow velocity and/or direction, and problems with PRB construction...” Permeable Reactive Barrier Failure? Probably the CSM. CRC CARE 2016 and ETI 2005 68 PRBs, 90% Awesome “Let’s not overcomplicate this - I just need a quick quote to simply excavate ” Confidential Ontario Site (2002): •Toxic airborne concentrations of CVOCs •Unable to excavate all impacted material Brute Force! 18 Former bulk storage location on “low permeability clayey silt”... ... extent misjudged by >3x 19 This is a 12 m deep excavation beneath a fuel tank in sand and gravel ... ...excavated three (3) separate times in order to get to closure: fuel penetrated over 1 m below the water table. 20 3,630 m 3 soil became 26,000 m 3 soil & 23,200 m 3 rock 72 Boreholes & Three Excavation Mobilisations Vertically Delineated to “Competent Rock” 21 The Bright Side: Blocking A Preferential Path in One Day’s Work (“Design Judo”) Bedding Material: 122,000 to 135,000 ng/L Ponded Water: 10,000 - 16,000 ng/L Inside Sewer Pipe: 8,000 - 12,000 ng/L Injection concept in plan 24 1 Let’sLookat KeyTopicsin a CSM... What Should a CSM Include? 1 2 Site History and Setting System and Site Boundaries Topography, drainage, surface water, climate Historic and current operations and practices Potential areas of environmental concern (“source zones”) Potential contaminants of concern – contaminant properties and behaviour Conceptual Site Model - The Puzzle Pieces 3 Identifying Contaminants of Concern (PCOCs) Phase 1 ESA (March 2000): Unit #105 - Existing dry cleaner (1996 – 2002) Unit #103 – Historic dry cleaner (1971 – 1996) Shopping Centre constructed in 1971 What are the likely contaminants of concern ? XXXX 4 5 Geology and Stratigraphy Regional and local Overburden – sedimentary; glaciology, depositional processes Bedrock – lithologies, facies, fracture networks, representative elementary volume 6 Hydrogeology Aquifers and aquitards Groundwater levels and elevations Hydraulic conductivity, gradients and velocities Hydrogeologic boundaries Courtesy, Andrew Cohen-Groundwater U 7 8 Contaminant Extent, Plumes and Pathways Soil, Groundwater and Soil Vapour Transport and Attenuation Processes Heterogeneity, Anisotropy and Scale 9 Receptors and Risk Terrestrial, aquatic, human Habitat Cultural Attributes Routes of exposure Toxicity and Dose Wildlife Consumption 10 If the Site is complex, you may need to have many views of the data – and additional layers of data Your CSM is alive and can only improve with time. If you are new to a project, look at all info with your CSM glasses on! - Jean-Pierre Davit, Italy Building the CSM 11 Key Presentation Tools for the CSM What to look for in a report... Work Safe, Home Safe 12 Data Presentation - Figures Plan Map (1:50 000 or larger) Topographic Map Site Plan showing cultural and physical features Sample Location Plan (i.e., well locations) Plan showing PCAs, APECS, PCOCs Stratigraphic cross sections Groundwater contour plans Soil, soil vapour and groundwater chemistry Work Safe, Home Safe 13 Topographic Plan 14 Site History and Setting - Identify all PCAs, APECs and PCOCs 14 •Locate and show the boundary of all APECs on a figure •Show all PCOCs (regulated) •May also want to show non- regulated risk drivers PCA – Potentially Contaminating Activity APEC – Area of Potential Environmental Concern PCOC – Potential Contaminant of Concern 15 Geology/Sedimentology 15 Eroded sand bank, BC coast Layered sand deposited in an ancient lake. (J.J. Clague) 15 16 Ever Seen a “Gravel Lens” in the Making? Geologic Interpretation putting geology back into the assessment... Capilano River, North Vancouver 17 JORDLAGER (Soil Conditions) Sand och lerskikt (detalj) ca 4 m under markytan This soil does not speak Swedish or English! 18 “Impervious” Clay Till (Christiansen, 2010) 19 Data Presentation – Figures (cont.) Stratigraphic Cross Sections At least one longitudinal + one transverse to flow Interpolated extent of strata Posted groundwater levels Posted chemistry (soil, groundwater, soil vapour Monitoring well completion intervals (screen plus filter pack) Work Safe, Home Safe 20 Borehole Logs Soil Conditions are described on borehole logs Key information should be provided 21 Stratigraphic Cross Sections Stratigraphic units are interpolated from borehole logs 22 Stratigraphic Cross Sections 23 Stratigraphy versus Hydrostratigraphy 23 silt clay coarse sand coarse sand gravel AQUITARD AQUIFER Geologic Units Hydrostratigraphic Units Hydrostratigraphic unit - one or more geologic units with similar hydrogeologic properties (e.g., hydraulic conductivity) 24 24 Recharge Area Recharge Area Discharge Area Recharge and Discharge 25 Good Overview of Hydrogeology https://www.youtube.com/watch?v=t3ua4bmYxG8 26 Data Presentation – Figures (cont.) Groundwater Elevation and Chemistry Contour Plan (s) data posted for each well for same day measurement Separate elevation plans for different dates Separate plans for each aquifer Separate plans for main contaminants of concern Work Safe, Home Safe 27 Plotting Groundwater Elevation Contours What’s missing? 28 What clarifications would you want? 29 Contouring Concentration Data (PCE, ug/L) Same Data – Two Stories! 30 Another (bad) Example The Green and Red Dot approach •No contours (no interpolation) •Data patterns not obvious •Cluttered •Etc. Why is this so common in 2025? 31 Data Presentation – Figures (cont.) Soil Vapour Chemistry Contour Plan (s) data posted for each well for same day measurement Separate plans for main contaminants of concern Work Safe, Home Safe 1000 ug/L 100 ug/L 10 ug/L 32 PouringdyedPCEintotheground DNAPLInjectionExperiment 3 2 PCE DNAPL at CFB Borden, University of Waterloo DNAPL Injection Experiment PCE DNAPL at CFB Borden, University of Waterloo Reality vs. Conceptualization 34 Conceptual DNAPLMigration 3 35 Let’s Try Sketching a CSM! Background Information Gas Station Site 1994 to 2024 2 USTs – diesel and regular gas Stratigraphy: I.Asphalt/Topsoil/Fill (0 to 0.3 m deep) II.Silty Fine Sand layer (0.3 to 4 m deep) III.Silty Clay Till layer (4 m to greater than 5 m deep) Water table 2 m to 2.5 m bgs LNAPL likely Vapours likely Groundwater inferred to flow south Exercise #1 1 Let’s Try Sketching a CSM! Background Information Gas Station Site 1994 to 2024 2 USTs – diesel and regular gas (1.8 m diam) Stratigraphy: I.Asphalt/Topsoil/Fill (0 to 0.3 m deep) II.Silty Fine Sand layer (0.3 to 4 m deep) III.Silty Clay Till layer (4 m to greater than 5 m deep) Water table 2 m to 2.5 m bgs LNAPL likely Vapourslikely Groundwater inferred to flow south Exercise #1 – Part A 2 Gas Station (Plan Map) 3 Let’s Try Sketching a CSM! 1)Take the piece of paper with the gas station 2)Grab a pen or pencil 3)Add in subsurface USTs 4)Sketch in Stratigraphy I.Asphalt/Topsoil/Fill (0 to 0.3 m deep) II.Silty Fine Sand layer (0.3 to 4 m deep) III.Silty Clay Till layer (4 m to greater than 5 m deep) 5)Draw the water table (say 2 to 2.5 m deep) 6)Add in “contamination” (e.g., gasoline LNAPL) 7)Add in a soil vapour and groundwater plume (transport pathways) 8)Add in receptors (human and ecological) Exercise #1 – Part A 4 Let’s Sketch Some Cross Sections A A’ B B’ 5 Cross Section A-A’ 0 m 1 m 2 m 3 m 4 m 5 m A A’ 6 Cross Section B-B’ 0 m 1 m 2 m 3 m 4 m 5 m B B’ 7 Let’s Try Sketching in 3D! 1)Take the piece of paper with the gas station 2)Grab a pen or pencil 3)Add in subsurface USTs 4)Sketch in Stratigraphy I.Asphalt/Topsoil/Fill (0 to 0.3 m deep) II.Silty Fine Sand layer (0.3 to 4 m deep) III.Silty Clay Till layer (4 m to greater than 5 m deep) 5)Draw the water table (say 2 to 2.5 m deep) 6)Add in “contamination” (e.g., gasoline LNAPL) 7)Add in a soil vapour and groundwater plume (transport pathways) 8)Add in receptors (human and ecological) Exercise #1 – Part A N 0 m 1 m 2 m 3 m 4 m 5 m 9 9 10 Let’s Try Sketching a CSM! Take a piece of paper Grab a pen or pencil Sketch a large 3-D box Add in the place you are sitting, the building, property lines, surface features Add in subsurface conditions (soil layers, water table) Add in a source of contamination Add in a soil vapour and groundwater plume (transport pathways) Add in receptors (human and ecological) You’ve made a CSM!! 11 Exercise 1 Part B Locate and Install Monitoring Wells Work Scope Four boreholes completed as wells Construction Details Well diameter & material type Screen length, end cap Filter pack material Impermeable seal or plug Backfill (anulus) material Surface completion N 0 m 1 m 2 m 3 m 4 m 5 m Where would you add 4 monitoring wells? 1 Using the CSM to Close the Site 1 CSM Risk & Options Assessment Outcome 2 ITRC (2004): “Remediation Process Optimization: Identifying Opportunities for Enhanced and More Efficient Site Remediation” As You Sow, So Shall You Reap Your greatest ability to influence the outcome is at project conceptualization 3 Risk Management Depends on the CSM Adapted from: U.S. EPA, 1988. “Guidance for conducting remedial investigations and feasibility studies under CERCLA (OSWER Directive 9355.3-01)”. Report Number EPA/540/G-89/004. U.S. Environmental Protection Agency, Washington, D.C. October 1988. Site Characterisation Establish Remedial Action Objectives Develop General Response Actions Describing Areas of Volumes of Media to Which Containment, Treatment or Removal May Be Applied •Determine New Data Needs •Develop Sampling Strategies, Data Quality Objectives, and Analytical Support •Acquire or Estimate Additional Data •Update Conceptual Site Model Combine Media Specific Approaches (Soil, Groundwater, Vapour, Sediment, Free Product) into overall alternatives SCREENING OF ALTERNATIVES DETAILED ANALYSIS OF ALTERNATIVES Scoping/context Need More/Different Data? Identify Potential Treatment and Disposal Technologies and SCREEN BASED ON TECHNICAL IMPLEMENTABILITY Garbage In, Garbage Out: Risk Estimation & Options Screening Cannot Be Better than the CSM Allows 4 Numerical Standards Remove contamination to comply with numerical standards Advantages: (Perceived) certainty No longer a contaminated site (at the moment) Disadvantages: Expensive, often cost-prohibitive for complex sites May not be physically feasible Risk-Based Management Determine risks and reduce excess risk to comply with risk- based standards Advantages: Cost-effective Better net benefit from resource allocation Disadvantages: Environmental liabilities & stigma remain Ongoing monitoring, maintenance, conditions Possible do-over if use case or risk understanding changes First: Add Goals & Objectives to CSM Pristine Restore perfect pre- impact state Advantages: Popular with stakeholder & NGOs Disadvantages: Rapid freezing leads to extinction of endemic infernal species Evolution of Practice 5 Understand *All* Relevant Goals and Objectives Sustainable Remediation Definition: “The elimination and/or control of unacceptable risks in a safe and timely manner while optimizing the environmental, social, and economic value of the work.” - ISO 18504:201 “Soil Quality – Sustainable Remediation” pub. 2017, reaffirmed 2023 SuRF-UK Framework (CL:AIRE, 2010) 6 1.Identify applicable technologies •Identify technologies that could address the identified contaminants in each of the affected media (soil, sediment, groundwater, surface water, soil vapour) in the CSM 2.Screen the technologies •Eliminate technologies that are likely infeasible because of refined CSM (contaminant nature & extent, geo- environmental setting, operational constraints) 3.Combine candidate technologies into comprehensive alternatives that have a reasonable chance of...wait for it... •Meeting goals and objectives in the context of the refined CSM Now: Evaluate Remedial Alternatives Natural Attenuation Injected Permeable Reactive Barrier (Mobility Control) Dual pump liquid extraction (Source Reduction) 7 Different Goals, Different Problems, Different Solutions Address the Cause Address the Core Address the Distal Plume(s) 8 Extraction – Physical Removal, Mass Transfer Excavation, pumping, vacuum extraction Treatment/Transformation - Physical, Chemical or Biological in situ – “in place” ex situ – “out of place”, e.g., after extraction Containment or Isolation Hydraulic (e.g., pump and treat) Physical (e.g., cut-off walls, caps, liners) Monitored Natural Attenuation *Not* “no action” Whatever Shall You Do? 9 Extraction/Physical Removal Example : Excavation Excavation remains very common because: Time is at a premium (permits, testing, design) Certainty is at a premium Uncertainties in the investigation are revealed SURPRISE!!! 10 Ex Situ Example: Biopiles (Aerobic Bio) Treatment/Transformation In Situ Example: Trap/Destroy PHCs 12 12 Containment or Isolation Examples of hydraulic containment Pumping well Drain Barrier Walls (with a pumping well – why?) Example of physical containment 13 Bedrock Soil Injection Intervals Bedrock Example – “Packers” Allow Injection in Specific Intervals 14 Permeable (“Passive”) Reactive Barriers Inobtrusive, long-term “passive” groundwater remediation along flowpath: Barrier design pegged to contaminant flux & residence time 16 ~12 Main Approaches 1000’s of Implementation Specifics Where to start? Ain't Nobody Got Time for That 19 http://www.frtr.gov/matrix2/section3/table3_2.pdf (last update – 2007) Initial Cut – Contaminant, Media, Availability 20 Use the CSM (now including goals/objectives and constraints) to identify alternatives most likely to work & do some rough dimensioning Analogy – similar sites/other experience Parametric estimates - $/m3, $/m, etc. Look at the data needs for likely options Spend time and effort on small set of alternatives with the highest likelihood of success Select Preferred Remediation Alternative (s) Refinement 1 Exercise #2 Corner(ing) Gas Options 1 2 Use the CSM to Short List Options 1)Review the CSM 2)Consider goals/objectives/constraints A.Existing on-site use will continue B.Tanks will be replaced in facility overhaul C.Owner and regulator insist on eliminating any further mobility & eliminating off-site risks for any future land uses 4)Pick two (2) different overall concepts/approaches for remediation/risk management 5)Consider – what one or two things would make one approach much better than the other? 6)Discuss at your table. Exercise #2 3 A.Refer to the screening table B.If you have time, find the two (2) interactive online remedy selection tools in the resource list and consult them! Exercise #2 - Continued 30 m 60 m 10 m from Centreline 5 m 10 m Silty Fine Sand Sandy Silt, Trace Gravel 5 6 7 Sketch Plan #1 8 Sketch Plan #1 9 Sketch Plan #2 10 Sketch Plan #2 1 Mind the (Data) Gap 1 2 3 Understand the Limitations of Your Data c i =concentration in stratum i q i = flow to well in stratum i during sampling 4 You need more than COCs: Chemistry/Biogeochemistry It’s not just *how* you would need to remediate – it can be *if* you need to remediate at all. California (1995): Over 1000 LUST Sites Mostly shallow groundwater (less than 5 meters) Benzene plume lengths seldom exceed 75 meters Texas (1997): 217 Sites Most (75%) benzene plume lengths less than 75 meters Edwards Aquifer (Karst) is exception (some exceeding 500 meters) South Dakota (1993): 75 Sites Most plume lengths less than 100 meters Conner meta study (2015): Median length at limit of 10 μg/L 30.7 to 56.3 meters for Benzene 33.5 to 54.3 meters for MTBE Figure: NRC (1993) Connor, J. A., Kamath, R., Walker, K. L. and McHugh, T. E. (2015), Review of Quantitative Surveys of the Length and Stability of MTBE, TBA, and Benzene Plumes in Groundwater at UST Sites. Groundwater, 53: 195–206. doi:10.1111/gwat.12233 7 And What About Civil & Geotechnical Constraints? Urban (NYC) UtilitiesShoring Collapse (Coquitlam, 2023) Beyond Delineation, Context is Everything Future land use, construction plans Location, authorities having jurisdiction (-> bylaws, policies, requirements) Relevant as-builts, utilities & overheads, servicing, layout, access, sensitive nearby receptors, property lines, easements, setbacks, rights of way, rail lines, site-specific concerns (UXO, Archy) Distribution of free phase (i.e., LNAPL, DNAPL, sheens), free-phase composition and characteristics (density, viscosity) Maximum and average concentrations of all contaminants of concern (water and soil), daughter products. Distribution (both area extent and vertical extent, on and/or off-site), age/weathering Stratigraphy, heterogeneities, migration pathways, boulders/cobbles, etc. Grain size distributions, soil classifications, approximate organic content (FOC?), compaction/density, (cut-offs, geotechnical construction – Atterbergs, SPT or CPT) Rock type, weathering, bedding, RQD, fracture dip/orientation, approximate strength, estimated secondary porosity Depth to water table and seasonal fluctuations Hydrostratigraphic units (i.e., aquitards/confining layers, aquifers) Hydraulic conductivities Hydraulic gradients (including vertical gradients & seasonal fluctuations) Groundwater flow direction/pattern, seasonal variability, estimated velocity Lateral and vertical extent of the groundwater plume Field Parameters: pH, DO, ORP, EC, temp Alkalinity, hardness, TDS Iron (dissolved), manganese (dissolved), sulphate, nitrate, nitrite Dissolved organic carbon (DOC), Chemical Oxidant Demand (COD), Natural Oxidant Demand (NOD) 10 Revised Final Extended Supplemental Phase III+? Avoid repeated re-mobs: Leverage local and regional data (formation characteristics, typical parameter ranges, neighboring site data, regional databases) Thoroughly understand the owner/client plans and constraints Tap your professional community Better initial data Test pits, daylighting and exploratory digs Continuous cores Targeted well screens Advanced ex-situ screening (cf. AISCT ® ) Material for benchtop treatability testing Rock – downhole characterization High resolution direct push data Density/compaction, gradation and hydraulics from geotechnical and hydrogeology/dewatering investigations Remedial Design Characterization (RDC) or equivalent 11 Rapid, High Resolution Site Data LIF MIP & LL MIP HPT Laser Induced Fluorescence (LIF) •Free Phase PHCs / LNAPL Membrane Interface Probe (MIP & LL MIP) •Dissolved Phase PHCs and VOCs Hydraulic Profiling Tool (HPT) •Subsurface Permeability and Conductivity Est . 12 Combined MiHpt / LL MiHpt probe data for contaminant and permeability data in a single push/location 13 HRSC data for “K”, Hydraulic Conductivity (m/day) HRSC data for VOCs in MIP 14 •Active overhead and buried utilities within proposed PRB alignment Hydrovac to clear locations prior to drilling •Working around active station including, pedestrians, public automobiles and employees of station •Combined MIP/HPT: ten (10) MiHpt locations in two (2)days along property boundary of active station •Remedial Design Characterization (RDC): Drilling completed at five (5) in one (1) day on-site Fifty-four (54) soil samples sent to Contractor's program for PHC analysis RDC completed to relate analytical numbers based on HRSC results Abbreviated Case Study: PHC’s at Operating Service Station 15 Abbreviated Case Study HRSC Results: •Utilized for vertical and horizontal data gap analysis and PRB design optimization •Good agreement with PID and FID data confirming PHC impacts along property boundary •PHC impacts estimate to start deeper than what previous information collected/provided Previous reports indicated ~5.5 mbgs min depth of impacts, MiHpt had more consistent PHC responses starting closer to ~6.5 mbgs, •Hydraulic Profiling Tool highlighted transport and storage zones within the subsurface Deep water table confirmed by HPT Some of highest PID and FID responses located in transport zones on Site 16 ConceptFinal Design LengthUp to 40 m 59 m Impacted Intervals5.5 to 9.5 mbgs 6 up to 11 mbgs* Est. Conductivity (m/s)1x10 -6 m/s – based on BH logs1.9x10 -4 m/s – enhanced by HPT Design based on # of locations1x BH/MW 1x BH/MW, 10x MiHpt and 5x RDC Amendment Design Conc.36 %wt Ranged from 24 to 48 %wt * - final PRB design had variable installation depth intervals along the length of PRB Original design would have missed a significant portion of the GW plume and under-dosed = FAILURE Better CSM Prevents Failure 17 Abbreviated Case Study: cVOCs at 7.9 to 12 m in Bedrock Downhole Geophysics: caliper, gamma, inductive conductivity, single point resistance, temperature, fluid conductivity, spontaneous potential and camera Injection Tracer Testing: 2,000 L of a tracer solution containing 40 mg/L of Rhodamine WT dye and 8,000 mg/L of potassium bromide and chased with 100 L of water – monitored for 6 months (loggers + grab samples) Remedial Design Characterization (RDC): 20 soil, 6 bedrock and 10 groundwater samples submitted to Contractor’s program 18 Better CSM Prevents Failure Initial Remedial Design: Target southeast portion of the site where cVOC plume in bedrock groundwater is leaving the property Target bedrock groundwater over depth interval of approx. 7.9 – 12.0 m bgs Two off-set rows of injection points on an approx. 4.6 m spacing Inject a 9% wt./wt. slurry of BOS 100® at a rate of approx. 650 L/m Initial PRB design would have missed the upper bedrock groundwater zone = FAILURE Refined Design: •Target southeast portion of the site where cVOC plume in bedrock groundwater is leaving the property •Target bedrock groundwater over depth interval of approx. 5.8 – 11.1 m bgs (i.e., shallower but thicker) •Two off-set rows of injection points on an approx. 6.1 m spacing (i.e., wider so less drilling costs for 10 vs 14 IPs) •Inject a 9% wt./wt. slurry of BOS 100® at a rate of approx. 1,050 L/m •Cumulative changes results in increased BOS 100® loading of approx. 33% for the PRB 19 Adapted to Canada from AACE® International Recommended Practice No. 107R-19 , “Cost Estimate Classification System – As Applied in Engineering, Procurement, and Construction for the Environmental Remediation Industries” Rev. October 5, 2021 Estimate ClassPrimary CharacteristicSecondary Characteristic PROJECT DEFINITION Expressed as % of complete definition END USAGE Typical purpose of estimate METHODOLOGY Typical estimating method EXPECTED ACCURACY Typical variation in low and high ranges at an 80% confidence interval of the P50 Class 50% to 2%Early investigations and preliminary planning (Phase II) Capacity factored, parametric models, judgment, or analogy L: -20% to -50% H: +30% to +175% Class 41% to 15% In-depth investigations, evaluation of remedial alternatives and remedy selection (Supplemental Phase II, Remedial Options Assessment) Equipment factored or parametric models L:-15% to -30% H:+20% to +50% Class 310% to 40% RDC, Preliminary design of selected remedy; Initial estimates for O&M and LTM (Initial Remedial Design) Semi-detailed unit costs with assembly level line items L:-10% to -20% H:+10% to +45% Class 230% to 75%Intermediate remedial design, refined estimates for O&M and LTM final remedial action/remedial action implementation plan, detailed implementation plan Detailed unit cost with forced detailed take- off L:-5% to -15% H: +5% to +20% Class 165% to 100%Pre-final/final remedial design Detailed/remedial action, O&M and LTM plans and cost estimates (Bid Price/Project Control Estimate) Detailed unit cost with detailed take- off L: -3% to -10% H:+3% to +15% Design Completeness = Cost and Schedule Certainty 20 AACE® International Recommended Practice No. 107R-19 “Cost Estimate Classification System – As Applied in Engineering, Procurement, and Construction for the Environmental Remediation Industries” Rev. October 5, 2021 80% Confidence Interval Estimate Accuracy Range *After* Inclusion of P50 Contingency Actual Cost P50 Contingency Example: Bulk earthworks are assessed as 200,000m3 at $25 per m3 with the quantity and rate combined range being -20% to +40%. The range of costs for this is: Lowest likely = (200,000 x $25) - 20% which equals $5.0m x 0.8 = $4.0m Highest likely = (200,000 x $25) +40% which equals $5.0m x 1.4 = $7.0m Most Likely = (200,000 x $25) - 0% = $5.0m Adapted from Australian Government Department of Finance, “Defining P50 and P80” last updated 2024-01-16 Best Case ≠ Most Likely Case 1 Exercise #3 Picking Your Horse 1 2 The Preferred Approach? 1)Go back to Exercise #2 and review “your two options and your most important considerations with respect to picking between them ” A.We’ll take 5 minutes to discuss the additional information you need to pick between your two approaches. B.Raise your hand to ask clarifying questions (facilitator will record answers for common reference) 2)Pick between your two likely approaches at your table. 3)Sketch out the implementation in more detail, as well as the locations and types of the additional data you need to advance the design. Exercise #3 3 4)Prepare a 30 to 60 second “elevator pitch” to the room of: A.What you recommend B.Why (advantages) C.What additional data you need D.How you intend to get it E.Why it’s worth spending the money to get the additional data Exercise #3 - Continued 4 Best Option & Supplemental Data - Plan 5 Best Option & Supplemental Data - Profile 6 (BOASD) Cross Section A-A’ A A’ Depth Scale 7 (BOASD) Cross Section B-B’ B B’ Depth Scale 8 (BOASD) Recommendations and Key Data Needs • • • • • • • 1 Wrap Up and Discussion Beyond Data – Part 2 2 Key Ideas A Conceptual Site Model (CSM) is an easily communicated, easily evaluated visual and narrative snapshot of your “total concept” of the actual (unseen) subsurface state of a site. Use a progressively refined and expanded CSM from the Phase I all the way through Remediation/Risk Assessment/Closure. “Asking questions” of the CSM identifies gaps and vulnerabilities at each stage in your expanding understanding of the site. Testing the predictions of the CSM shows whether or not it is sufficient. Progressively updating and expanding the CSM evolves it from little more than hunches and guesses into a detailed, fact-based model that defensibly guides decision-making with the appropriate level of supporting data at each major stage in the site’s path to closure. 3 4 5 Not an End: A Beginning Instructor: Guy Patrick, M.Sc., P.Eng., CSAP [email protected] (604) 219-8437 Volunteer Facilitators: Pete Craig, M.Sc., PChem ([email protected] ) Eric Cowan B.A.S., C.E.T. ([email protected] ) 6 Thank You Beyond Data - Part 2 Conceptual Site Models for Effective Remediation and Risk Management