Beyond Dig and Haul: A survey of Remedial Technologies. NYS Department of Environmental Conservation

Transcription

1 Beyond Dig and Haul: A survey of Remedial Technologies

2 Agenda (20 Minutes) Excavations Bioremediation ISCO SVE Thermal treatment

3 Remedy Selection Do not select the remedy before you investigate the site First and foremost, the remedy must be protective of people and the environment Second, you have to follow the rules (i.e. comply with the applicable standards, criteria and guidelines)

4 DER-31 Green Remediation Consider all environmental effects of the cleanup Minimize emissions (CO2, contaminants) Use of resources (landfills, minerals, energy) Maintain or improve habitat

5 Climate Change Resilience Sea level rise (Coastal areas, Hudson River Estuary) Will your soil cover be under water and wash away in 20 years? Flood plains Increased frequency and intensity of storms.

6 Hierarchy Permanently destroy it Permanently remove it Permanently eliminate the risk Prevent exposure Engineering controls Institutional controls

7 Excavations There will always be a role for excavation and off-site treatment and disposal. It is permanent Verification (you know what did and did not get accomplished) Target source areas. Most accessible. Note on backfill (BUDs)

8 Combining Technologies Many of the in-situ treatment technologies have limited effectiveness on source material Excavation is usually the right technology for the most accessible source material.

9 Disposal vs treatment Disposal: Contaminated soil can be used as alternate daily cover, conserving mineral resources Treatment: Thermal desorption Chemical stabilization

10 Chemical Stabilization Most commonly used on lead Raise ph, react lead to create an insoluble mineral Eliminate the hazardous characteristic Performing in-situ avoids some regulatory issues (its not a hazardous waste until it is generated ) Can work with other metals

11 Things that make excavations less implementable Buildings and other obstructions Odors and vapors (Sprung structures) Infrastructure (roads and bridges) Geotechnical (shoring) Water

12

13

14 In-Situ Chemical Oxidation ISCO

15 Set Clear Goals What Works Probably not meeting GW standards Often combine with bio or MNA Permanganate and persulfate are beginning to dominate the market Focusing mainly on CVOCs Source areas (but not NAPL) Below the water table (SVE above water)

16 What Doesn t Work Tight Soils Matrix diffusion Rebound Poor delineation NAPL some success, but I m not sold yet

17 Enhanced Bioremediation Reductive Dechlorination

18 Chlorinated Solvents PCE, TCE, TCA

19 When to use enhanced bio Where it s already working Plume control Anywhere you don t want to use ISCO Tight soils Poor access Poor delineation High ISCO demand Mention carbon injection

20 Non-Chlorinated Organics Air injection (sparging). Oxygen injection Green options ORC thrown into hole after excavation: No significant effect. Would generally not bother. Sulfate and nitrate amendments

21 Note on MNA Monitored natural attenuation Very specific definition You need to set a goal and a deadline Establish a fallback technology if you don t meet your goal by that time.

22 Phytoremediation Uptake of contaminants Accumulated in plants which then need to be disposed Expired into the air (essentially a dilution remedy, but mention photodegradation). Degrading chemicals White rot fungus was oversold Bacteria appear to be far more effective than plants

23 Soil Vapor Extraction (SVE) Vadose zone source (very high soil vapor) Permeable soil remedy Source areas Hit it hard and get it done Running the system for a long time is not cost effective or sustainable

24

25 Combining Technologies

26 In-Situ Thermal

27 Where excavation and AS/SVE are not good fits, in-situ thermal treatment has emerged as a legitimate alternative.

28 Think Thermal When Deep contamination Excavation is impractical Low permeability soils You need complete cleanup fast You know where your source is Volatile organics

29 Thermal Desorption Think of it as thermally enhanced AS/SVE Expansion during phase change Includes vapor extraction Advantages: Short duration, final Works in all materials, including bedrock and clay

30 Delivery of heat Electrical Resistive Heating (ERH) Ideal for clay, heterogeneous soils We have had good luck in sandy soils too Be aware of stray current potential Thermal Conductive Heating Works everywhere The only choice if you need to get above 100ºC

31 Ideal Cleaners IRM construction

32 Ideal Cleaners ISTD operating

33 Power Control Units and Cooling Towers

34 Condensers, 40hp Blowers, PCUs

35 Vapor Phase Carbon Vessels

36 Vapor Phase Carbon Vessels

37 Interior Bldg 57A

38 Interior Bldg 57A Quiz 2

39 Sustainability Carbon footprint for electrically heating is comparable to digging and hauling it 65 miles (source: TerraTherm)

40 Limitations We have had the most success with VOCs SVOCs need higher temps, dewatering High permeability = heating a lot of water

41 Steam Has been used effectively (Visalia) Adding a lot of water to the system Seems more like thermally enhanced pump and treat than Thermally enhanced SVE

42 Brief mention of STAR Full-scale implementation underway at a coal tar site in Newark, New Jersey. deep sand unit located up to 35 feet below the water table destroying coal tar at a rate of approximately one ton per day.

43

44