LONG TERM MONITORING DATA EVALUATION OF BIOAUGMENTATION

DURING ISCR-ENHANCED BIOREMEDIATION OF TCE DNAPL

James G.D. Peale, RGErik I. Bakkom, PE (Maul Foster & Alongi Inc.)

Jeff Roberts, Sandra Dworatzek (SiREM Laboratories)

Josephine Molin(FMC Environmental Solutions)

June 2013

Site Overview Technology Summary Problem Statement Analysis Results Summary Implications

TOPICS

Former MGP waste site redeveloped for manufacturing in 1970s

80+ acres adjacent to Portland Harbor NPL site TCE released from a recycling system (1980-1985) Impacts from release discovered in 2002 TCE DNAPL Source Zone

Impacts from about 5-34 m bgs TCE up to 592,000 ug/L (DNAPL levels)

No TCE DNAPL observed Cis-1,2-DCE up to 90,800 ug/L Very little VC (< 100 ug/L)

Site Overview

Site Overview

Technology Summary

EHC Powdered blend of zero-valent iron (ZVI) and hydrophilic

organic carbon Creates strongly reducing conditions in groundwater for in situ

chemical reduction (ISCR) ISCR results in abiotic dechlorination and supports anaerobic

bacteria

KB-1 Anaerobic consortium of dechlorinating bacteria Includes dehalococcoides sp. Requires ORP < -75 mV

Both technologies demonstrated success for dissolved CVOC plumes

Technology Summary

EHC+KB-1 Full-Scale Implementation 46 m x 21 m x 3 m PRB – Source area only Injected from ~12 – 34 m bgs Supplemental upgradient areas

200+ injection points ~269,400 kg EHC 1,831 L KB-1

Direct-push drilling 23 Performance Monitoring Wells

Injection Layout

Injection Layout

Source Area Geometry

Problem Statement

Remedial action objective is 11,000 ug/L Threshold indicator for TCE DNAPL Achieved in less than 12 months

Achieved mean TCE 3 ug/L Declining cDCE and VC, but still elevated in

some wells Dhc counts 107 – 108

Question: how long can this continue? Will we see rebound?

Problem Statement

How long will Dhc sp. flourish? Organic carbon needs

(other) Continued reducing conditions?

Field data Other functional requirements?

Continued cVOCs?

Long-Term Data Sets

Pilot Study Data 2006-2008 Shallow and deep wells, within and

downgradient of injection zone Full-scale Data

2009-present 19 wells + pilot study wells

Monitoring program includes: VOCs, TOC, Dhcv, vCRA Field parameters

CVOC Data – kg estimated in source area (EVS)

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

11/1/2008 5/20/2009 12/6/2009 6/24/2010 1/10/2011 7/29/2011 2/14/2012 9/1/2012 3/20/2013

TCE (kg) cDCE VC Ethene

CVOC Data – normalized (C/C0) to show ethene generation (also VC…uh oh)

0.001

0.01

0.1

1

10

100

Nov-08 May-09 Dec-09 Jun-10 Jan-11 Jul-11 Feb-12 Sep-12 Mar-13

TCE cDCE VC Ethene CVOC

Not to worry - VC Data regression

y = -0.1601x + 6676.3R² = 0.7136

-20

0

20

40

60

80

100

120

140

160

Dec-11 Apr-12 Jul-12 Oct-12 Jan-13 May-13 Aug-13 Nov-13 Mar-14 Jun-14

Estimated VC Mass (kg)

Estimated VC Mass (kg) Linear (Estimated VC Mass (kg))

TOC Data – Mean of Full Scale Data Set (n=23)

194

0

500

1000

1500

2000

2500

3000

3500

Total Organic Carbon (Total and Dissolved)Primary Well Group (mg/L)

TOC (Total) - Mean TOC (Total) - Geometric Mean TOC (Dissolved) - Mean TOC (Dissolved) - Geometric Mean

Background TOC ~ 10 mg/L

Dhc Data – Full Scale Data Set (n=23)

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

1.E+10

7/1/2009 1/17/2010 8/5/2010 2/21/2011 9/9/2011 3/27/2012 10/13/2012 5/1/2013

DHCFull Scale Well Group (Count)

1/2 of non-detect values used

vCRA Data – full scale data set

1.00E+04

1.00E+05

1.00E+06

1.00E+07

1.00E+08

1.00E+09

1.00E+10

6/1/2008 12/18/2008 7/6/2009 1/22/2010 8/10/2010 2/26/2011 9/14/2011 4/1/2012 10/18/2012 5/6/2013 11/22/2013

vcrA Primary Well Group

(Count)

1/2 of non-detect values used

TOC and DHC Data – Long Term (n=4)

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

1.E+08

1.E+09

0

500

1000

1500

2000

2500

3000

3500

4000

5/1/2006 9/13/2007 1/25/2009 6/9/2010 10/22/2011 3/5/2013

Dhc

(cou

nt)

TOC

(mg/

L)

WS-19 WS-18-101 WS-18-71 DHC

ORP data

-200

-150

-100

-50

0

50

100

150

200

37922 38288 38653 39018 39383 39749 40114 40479 40844 41210

Redox potentialMean of Primary Well Group (n varies) eH - Mean

Analysis

All indicators look good! VOC mass decreasing Sustained elevated TOC levels Sustained negative ORP levels Continued ethene generation Regression predicts VC decrease by 2014

Some indicators look iffy? Would like to see higher Dhc numbers? Others?

Results

Success!

Other considerations DNAPL/CVOC reduction

Other Useful?

Summary (tbd)

Literature range sets boundaries 20 – 750 yrs (latter less useful) Developing data set

Regression provides simple tool for prediction Dual rates observed and should be considered Early consumption followed by equilibrium

Modeling is promising approach Estimates match lower range of regression Can provide conservative (short) predictions to

improve site planning/closure

Implications (tbd)

Micro-scale ZVI is extremely durable Data fit well with other observations

Similarity to presumed P&T timeframes (30 yrs) How do we manage long-term?

Is monitoring required to demonstrate complete exhaustion?

How can we extend confidence of this long-term remedy to support site closure?

Acknowledgements/Questions

Thank you.

SiREM Laboratories FMC Environmental Solutions

Questions?