Real-time Performance Monitoring of Chemical Fixation Treatment - PowerPoint PPT Presentation

Real-time Performance Monitoring of Chemical Fixation Treatment Paul R. Lear, Ph.D.

Presentation Outline • Real-Time Performance Monitoring for Chemical Fixation – Why is it necessary? – How is it done? • Example of it’s applicability – Glass Landfill Site in Monaca, PA October 23, 2012 2

Chemical Fixation (or Stabilization) • Converts contaminants in their least mobile, soluble or toxic form • Mix design is often based on laboratory treatability testing – One or two samples collected from a site – Assumed to be representative • Contractor bases treatment on the results of laboratory testing October 23, 2012 3

The Real World • Sites are not homogeneous – Waste materials vary in terms of composition, contaminant levels • Implementation of the mix design can be less than successful due to this variability – Performance monitoring is typically based on TCLP or SPLP leachability testing (minimum 2 days TAT) – Receive failing results and then have to determine why – Meanwhile processing needs to continue October 23, 2012 4

Real-Time Performance Monitoring • Many chemical fixation reagents rely on pH control to some extent – Determination of pH can be helpful in performance monitoring • Mimicking TCLP or SPLP extraction and determining equilibrium pH can provide real- time performance monitoring October 23, 2012 5

“Mini” -TCLP or SPLP • Start with 5 to 10 g of treated waste instead of 100 g. • Utilize the same leaching solution – TCLP Extraction Fluid Type 1 or 2 – SPLP East or West of Mississippi extraction fluid • Utilize the same liquids:solids ratio – 20 mL extraction fluid per g of treated waste October 23, 2012 6

“Mini” -TCLP or SPLP (cont.) • Extraction 12 time needs 11 to be long 10 enough so 9 that near pH 8 equilibrium 7 conditions 6 Minimum have been Extraction 5 Time reached 4 0 200 400 600 800 1000 1200 1400 1600 Time (min) October 23, 2012 7

Real-Time Performance Monitoring • Correlate 11 equilibrium 10 pH to results 9 from full and complete test 8 pH to determine 7 minimum pH Treated with 3% EnviroBlend Retreated with an additional 0.5% Enviroblend 6 to indicate Treated with 3% EnviroBlend Retreated with an additional 0.5% Enviroblend 5 passing Treated with 3.5% EnviroBlend Retreated with an additional 0.25% Enviroblend 4 result 0 20 40 60 80 100 120 140 Time (min) October 23, 2012 8

Real-Time Performance Monitoring • Obtain 11 frequent 10 Likely to samples Pass 9 Not Likely during to Pass 8 operations pH 7 to monitor AM Sample 6 performance Midmorning Sample 5 and tweak Noon Sample (increased Enviroblend %) mix design 4 0 20 40 60 80 100 120 140 Time (min) October 23, 2012 9

Real-Time Performance Monitoring • Treated 11 material 10 with low 9 pH needs to 8 pH be retreated 7 Treated with 3% EnviroBlend 6 Retreated with an additional 0.5% Enviroblend Treated with 3% EnviroBlend Retreated with an additional 0.5% Enviroblend 5 Treated with 3.5% EnviroBlend Retreated with an additional 0.25% Enviroblend 4 0 20 40 60 80 100 120 140 Time (min) October 23, 2012 10

Monaca Glass Project • Waste glass, debris, and soils disposed of in a ravine near Monaca, PA over a 50 year timeframe • Surface water in the ravine impacted by lead, primarily from the waste glass which failed TCLP for lead • Responsible party agreed to treat the 25,000 cy of glass and soils to make it RCRA non-hazardous, place it on-site, and cap October 23, 2012 11

Monaca Glass Project (cont.) • Treatability testing on several samples of the site material suggested that it may be made RCRA non-hazardous if treated by 3% EnviroMag – Not all samples were successfully treated with this mix design October 23, 2012 12

Monaca Glass Project (cont.) • Design involved – Excavation, – Debris removal, – Size reduction to -1/2 inch, – Pugmill mixing with 3% EnviroMag – Compaction in 8 inch lifts to 95% maximum modified Proctor density • Placed and compacted material was to be capped with low permeability clay October 23, 2012 13

Monaca Glass Project (cont.) • Pilot testing consisted of ten 100 cy stockpiles of excavated material, all treated with 3% EnviroMag • Only 30% of the pilot- test stockpiles passed (TCLP < 5 mg/L) – Passing stockpiles contained only glass and little to no soil or debris – The more soil, the higher the TCLP-leachable lead and the lower the pH after the 18 hour TCLP extraction • Retreatment with an additional 3% EnviroMag (6% total) allowed failing stockpiles to pass October 23, 2012 14

Monaca Glass Project (cont.) • Client was not willing to proceed if 6% EnviroMag required for the treatment • WRScompass suggested that we could utilize real- time monitoring to evaluate the treatment and minimize the EnviroMag usage – Evaluate soil content of feed material to select a starting EnviroMag addition rate – Real-time monitoring on every 200 tons treated – Adjust EnviroMag usage based on real-time monitoring • Oversight Engineer was skeptical, but agreed to let us try October 23, 2012 15

Monaca Glass Project (cont.) • Real-time monitoring on every 200 tons treated – Determined near-equilibrium pH in TCLP Extraction Fluid #1 – Near-equilibrium pH above 9 was correlated to passing TCLP results – Stockpiles with near-equilibrium pH below 9 were set aside for re-treatment – Adjust EnviroMag usage up or down as necessary October 23, 2012 16

Monaca Glass Project (cont.) • Overall results of real-time monitoring – 65% of the 200 tons stockpiles were cleared by real-time monitoring (35% required re-treatment) – More than 95% of the stockpile cleared by the monitoring had TCLP lead concentrations less than 5 mg/L – Over 95% of retreated stockpiles passed – EnviroMag usage ranged from 1.5% to 4.5% with an overall usage of 3.4% October 23, 2012 17

CSX Benton Harbor Project • Former scrap yard and battery recycling operation adjacent to rail line • Disposal of battery casings and lead plates on-site results in lead contamination in soil and groundwater October 23, 2012 18

CSX Benton Harbor Project (cont.) • Approved Remedial Action included: – Excavation of all lead- impacted soil/debris – On-site stabilization to render the material non-hazardous – Transportation off-site for disposal as a non-hazardous waste – Backfill with clean fill and site restoration October 23, 2012 19

CSX Benton Harbor Project (cont.) • Contractor chose to stabilize the excavated soil and battery casings using 5% Portland cement October 23, 2012 20

CSX Benton Harbor Project (cont.) • Early failure rate of 25% • Contractor keep on treating piles – Near 50% project completion, site was spoil- bound with piles of failed material October 23, 2012 21

CSX Benton Harbor Project (cont.) • CSX and EPA Region V became concerned • Review of operations indicated that – Variable soil:debris ratio likely cause of high failure rate – Real-time feedback to operations was required October 23, 2012 22

CSX Benton Harbor Project (cont.) • Real-time monitoring on every pile during treatment – Determined near- equilibrium pH in TCLP Extraction Fluid #1 – Near-equilibrium pH above 8 and below 11was correlated to passing TCLP results October 23, 2012 23

CSX Benton Harbor Project (cont.) • Stockpiles with near- equilibrium pH below 8 or above 11 were set aside for re-treatment – Piles below 8 had additional Portland cement added – Piles above 11 had additional waste added • Remixed and resampled retreated piles October 23, 2012 24

CSX Benton Harbor Project (cont.) • Overall results of real- time monitoring – All failed piles successfully treated (90% passed on 1 st retreat) – Less than 5% of the pile cleared by the monitoring had TCLP lead concentrations greater than 5 mg/L (fail) – CSX, EPA Region 5, and contractor happy October 23, 2012 25

Questions or Comments? plear@wrscompass.com 865-919-5205 October 23, 2012 26

Thank you for your time today. Visit us at www.WRScompass.com October 23, 2012 27 27