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

Real-time Performance Monitoring of Chemical Fixation Treatment

Paul R. Lear, Ph.D.

October 23, 2012 2

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 3

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 4

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 5

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 6

“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 7

“Mini”-TCLP or SPLP (cont.)

• Extraction

time needs to be long enough so that near equilibrium conditions have been reached

4 5 6 7 8 9 10 11 12 200 400 600 800 1000 1200 1400 1600 Time (min) pH

Minimum Extraction Time

October 23, 2012 8

Real-Time Performance Monitoring

• Correlate

equilibrium pH to results from full and complete test to determine minimum pH to indicate passing result

4 5 6 7 8 9 10 11 20 40 60 80 100 120 140

Time (min) pH Treated with 3% EnviroBlend Retreated with an additional 0.5% Enviroblend Treated with 3% EnviroBlend Retreated with an additional 0.5% Enviroblend Treated with 3.5% EnviroBlend Retreated with an additional 0.25% Enviroblend

October 23, 2012 9

Real-Time Performance Monitoring

• Obtain

frequent samples during

• perations

to monitor performance and tweak mix design

4 5 6 7 8 9 10 11 20 40 60 80 100 120 140

Time (min) pH AM Sample Midmorning Sample Noon Sample (increased Enviroblend %) Not Likely to Pass Likely to Pass

October 23, 2012 10

Real-Time Performance Monitoring

• Treated

material with low pH needs to be retreated

4 5 6 7 8 9 10 11 20 40 60 80 100 120 140

Time (min) pH

Treated with 3% EnviroBlend Retreated with an additional 0.5% Enviroblend Treated with 3% EnviroBlend Retreated with an additional 0.5% Enviroblend Treated with 3.5% EnviroBlend Retreated with an additional 0.25% Enviroblend

October 23, 2012 11

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 12

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 13

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 14

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 15

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 16

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 17

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 18

CSX Benton Harbor Project

• Former scrap yard and

battery recycling

• peration adjacent to rail

line

• Disposal of battery

casings and lead plates

• n-site results in lead

contamination in soil and groundwater

October 23, 2012 19

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 20

CSX Benton Harbor Project (cont.)

• Contractor

chose to stabilize the excavated soil and battery casings using 5% Portland cement

October 23, 2012 21

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 22

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

• perations was required

October 23, 2012 23

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 24

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 25

CSX Benton Harbor Project (cont.)

• Overall results of real-

time monitoring

– All failed piles successfully treated (90% passed on 1st 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 26

Questions or Comments?

plear@wrscompass.com 865-919-5205

October 23, 2012 27 27

Thank you for your time today.

Visit us at www.WRScompass.com