Improved Management/Remediation of Legacy Contaminated Sites Through High-Resolution Characterization

Transcription

1 Improved Management/Remediation of Legacy Contaminated Sites Through High-Resolution Characterization Jim Langenbach, P.E., BCEE Principal Engineer Geosyntec Consultants, Cape Canaveral, FL April 2013

2 Site Location Kennedy Space Center, Florida Located on east coast of Florida on Merritt Island, a barrier island between the Florida mainland and the Atlantic Ocean Operated by NASA since 1962 Utilized for active launch operations associated with Saturn program (1960 s and 70 s) and space shuttle through 2011

3 Site Location Over 100 legacy contaminated sites in NASA RCRA program Primary contaminant is trichloroethene (TCE) and breakdown products Releases occurred yrs ago (Saturn program era) Many challenges associated with the identification of historic release locations (i.e. lack of obvious tank, sump, degreaser, etc.)

4 What is High-Resolution Site Characterization? EPA Definition: High-resolution site characterization (HRSC) strategies and techniques use scale-appropriate measurement and sample density to define contaminant distributions, and the physical context in which they reside, with greater certainty, supporting faster and more effective site cleanup. DPT072 Interval (ft, BLS) TCE (µg/l) cdce (µg/l) VC (µg/l) 8 to U 1.0 U 1.0 U 16 to U 1.0 U 1.0 U 26 to U 1.0 U to ,000 48,000 4, to 45 1, to U 56 to J 61 to U Mass!

5 Why High-Resolution Site Characterization? Technology to cost-effectively implement high resolution data collection and analyses has increased in availability and type: Direct-push technology (DPT) and sonic drilling Mobile analytical laboratories Membrane interface probe (MIP), hydraulic profiling tool (HPT) Passive Flux Meter Provides enhanced understanding of Conceptual Site Model Reduced uncertainty with regards to plume delineation Refined understanding of source mass/dnapl distribution Reduced risk of missing a source or treating the wrong area Increased stakeholder confidence More effective Feasibility Study evaluations when screening remedial alternatives

6 Why High-Resolution Site Characterization? Refined cleanup cost estimates and timeframes Improved ability to manage costs (capital and annual expenditures for cleanup) Better understanding of mass and contaminant distribution results in improved predictions of cleanup timeframes Facilitates focused source remediation strategies Accounts for heterogeneities (scale appropriate measurements) Reduced costs associated with targeted remediation Typically shorter active remediation timeframe Capital is spent on treating primary mass (lowest $/lb)

7 High Resolution Screening with 3D Modeling Geosyntec has worked with NASA and NASA s teaming partners to develop and implement HRSC strategies at multiple KSC sites Implemented via DPT groundwater sampling with mobile laboratory analysis, and may include saturated soil sampling, MIP and HPT borings

8 Case Study KSC Sites with HRSC GSA Seized Property 1,500 ft long/27-acre (11 hectares - hm 2 ) VC plume emanating from shallow PCE source area 364 samples from 118 DPT locations plume transect approach Remedial actions implemented and completed Vehicle Assembly Building (VAB) Area Identified primary TCE and cdce impacts in less than 1 acre (0.4 hm 2 )area migrating through narrow depth interval of less than 10 ft 857 samples from 160 DPT locations concentration-based grid approach Source and high-concentration plume swath remedial actions implemented

9 GSA Seized Property - Site History Site a ~6 acre (2.4 hm 2 ) property within the Industrial Area at KSC Formerly used to store and auction seized vehicles Chlorinated solvents identified in groundwater no obvious source location (i.e. tank, sump, degreaser, etc.) 9

10 High-Resolution Site Characterization Assessment completed in 2008 Detailed assessment and follow-up DPTwells revealed: 1,650 ft dissolved plume (primarily vinyl chloride) PCE source area Plume transport primarily in 10 to 21 ft bls interval Dechlorination to vinyl chloride >1 and <100 µg/l vinyl chloride >100 and <1,000 µg/l vinyl chloride >1,000 µg/l vinyl chloride PCE Source Area

11 DPT transects within low concentration plume area Higher-density (laterally and vertically) DPT locations in area of highest concentration Monitoring well network strategically placed following HRSC

12 HRSC Source Area Results /Interim Measure (IM) PCE source area identified from 8 to 12 ft below grade (water table at 4 ft): PCE groundwater concentrations up to 32,000 µg/l Saturated soil PCE up to 130,000 µg/kg Limited PCE footprint laterally and vertically based upon HRSC Wet excavation to 13 ft below grade: 442 tons of PCE impacted soils removed electron donor addition to open hole Source area addressed: Max PCE <3 µg/l in former source area wells PCE >3 ug/l PCE >3,000 ug/l PCE >30,000 ug/l PCE >300 ug/l

13 HRSC Source Area Results/ Bioremediation Groundwater IM Purpose: Remediate groundwater downgradient of former source area with elevated VOCs: Approximately 5,000 ft2 area treated VOCs focused in ft depth interval Bioremediation with augmentation and solar-powered groundwater recirculation Goal: Reduce VOC concentrations in treatment zone to less than 3 µg/l TCE, 70 µg/l cdce, and 100 µg/l vinyl chloride Result: Achieved treatment objectives within 9 months (with regulatory approval) HRSC resulted in (1) accurate CSM, (2) focused remedial efforts, (3) predictable costs ($300K for groundwater IM), and (4) no surprises

14 Mobile Launch Pad/ Vehicle Assembly Building Area 4,000 gallon TCE spill 1960 s ½ acre (0.2 hm 2 ) TCE source area 100+ acre dissolved VOC plume SAMPLE LOCATION SPACING RULES OF THUMB > 3,000 µg/l TCE, 25 ft spacing > 300 µg/l, 50 ft spacing Previously Remediated Former Source Area

15 Three Dimensional Modeling of Source Area Source area > 3,000 µg/l TCE HRSC DPT data 3D model for bioremediation design and well network placement Achieved source treatment remediation goals in 2 yrs Data point used for interpolation 30,000 µg/l TCE 3,000 µg/l TCE 1,000 µg/l TCE

16 Mobile Launch Pad/ Vehicle Assembly Building Area A A A A Dissolved Plume Core: Identified TCE and cdce impacts migrating through narrow depth interval HRSC aided in design of air sparge system currently being implemented

17 DPT transects/grid within lowerconcentration dissolved plume area Higher-density (laterally and vertically) DPT locations in area of highest concentration Grid spacing of DPT samples based upon concentration Vertical sampling intervals based upon VOC distribution

18 Benefits Development of accurate CSM higher level of certainty Facilitates effective remedial evaluation selection of appropriate remedial technology Designs with more predictable/manageable costs and timeframes 3D model communicates the CSM to the stakeholders a picture is worth a 1,000 words This strategy can be scaled up or down based on size and conditions of the site and project budget

19 Acknowledgements Rebecca Daprato, Ph.D., P.E., Geosyntec Michael Deliz, P.G., NASA Harry Plaza, P.E., NASA NASA Remediation Team

20 Questions? Geosyntec Consultants 6770 S. Washington, Ave., Suite 3 Titusville, FL (321) Jlangenbach@geosyntec.com