18-Env-B4 Site Assessment and Remediation · May 2014
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2014 — 04-Env-B4 / Site Assessment and Remediation. 3 hours duration; open-book exam (any non-communicating calculator permitted). The paper is split into Section A (five questions, candidates asked to answer three) and Section B (three questions, candidates asked to answer two), each question worth 20 marks. All eight questions are solved below for completeness.
Reference texts. Suthersan & Payne, Remediation Engineering: Design Concepts (CRC Press); Gavaskar, Gupta, Sass, Janosy & O'Sullivan, Design Guidance for Application of Permeable Reactive Barriers for Groundwater Remediation (Battelle/EPA, 2000); ASTM E1527 Standard Practice for Phase I Environmental Site Assessments and ASTM E1903 Standard Practice for Phase II ESA; Mercer & Cohen (1990), “A review of immiscible fluids in the subsurface,” Journal of Contaminant Hydrology; Freeze & Cherry, Groundwater; Davis & Cornwell, Introduction to Environmental Engineering (6th ed.); Ontario Reg. 153/04 under the Environmental Protection Act (Record of Site Condition regime); BC Environmental Management Act — Contaminated Sites Regulation.
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
A plant closure triggers a Phase II ESA both to satisfy corporate environmental liability policy before the parcel is sold or repurposed and, in most provinces, to support any decommissioning or site-condition filing required as part of the closure. A cold-heading/fastener plant's principal environmental concerns come from metalworking fluids (soluble oils, straight cutting oils, sometimes historically chlorinated degreasers such as TCE or PCE used to clean parts before plating or coating), the base and plated metals themselves (Zn, Cu, Ni, Cr, and possibly Cd from any plating line), and ancillary infrastructure (fuel/oil storage tanks, transformers that may contain PCB-oil, and floor drains tying into an on-site septic or storm system).
The program should collect soil samples (both near-surface, 0–0.5 m, to capture surface spills and leaks, and deeper borings advanced to the water table beneath floor slabs and drain lines, to check whether any dense chlorinated solvent has migrated downward), groundwater samples from monitoring wells screened at the water table, and — because metalworking fluids and chlorinated degreasers are volatile or semi-volatile — soil-vapour samples where a REC for VOCs is suspected. If demolition is anticipated, building-material sampling (asbestos-containing materials, lead paint, PCB-containing transformer oil and light ballasts) should also be scoped, and surface-water/sediment sampling added if the plant discharges to a ditch or watercourse.
Sampling should target every Area of Potential Environmental Concern (AOPEC) identified in the preceding Phase I: aboveground/underground fuel and lubricant storage tanks and their fill/vent piping; the cold-heading and machining lines themselves, especially floor drains, trench drains, and sumps that historically received spent cutting fluid; any parts-washing or vapour-degreasing station; the plating/finishing area if one exists; waste-oil and scrap-metal storage and loading-dock areas (spill potential from drum handling); and outfalls or catch basins. Both source-area borings/wells and downgradient property-boundary compliance wells should be included so that any plume is bounded, not just detected.
Soil is typically collected by direct-push (Geoprobe) or hollow-stem-auger drilling with split-spoon or acetate-liner sampling, using dedicated or thoroughly decontaminated (steam/Alconox wash, distilled-water rinse) equipment between locations to prevent cross-contamination; groundwater is collected from dedicated wells after low-flow purging to stable field parameters (pH, conductivity, turbidity, DO). Sample containers and preservation are matched to the analyte: VOC-sensitive samples (solvents) go into 40 mL glass vials with zero headspace, either unpreserved and cooled or preserved with HCl to pH<2; semi-volatiles/PAHs into amber glass jars (protected from light); metals into HDPE bottles, often field-filtered and preserved with HNO&sub3; for dissolved-metals analysis in groundwater. All samples are labelled, logged on a chain-of-custody form at the moment of collection, and immediately placed on ice in coolers to maintain 4°C. Coolers are shipped by courier under custody seal to a CALA-accredited analytical laboratory, scheduled so that samples arrive well within the method-specific holding times (commonly 14 days to extraction/48 hours to analysis for VOCs in water, 14 days for VOCs in soil, and up to 6 months for metals), with the signed chain-of-custody accompanying the shipment at every transfer of possession.
