MSECA Seminar Presentation by Doug Carvel, P.E

MECX, Inc.

www.mecx.net

A Service-Disabled Veteran-Owned Small Business

LIFE CYCLE

CONCEPTUAL SITE MODEL

Presentation Overview

• Flaws in Historic Site Assessment

• What should be the Primary

Objective of Assessing a Site?

• Objective of a CSM

• CSM Components

• Sample Site Exercise

• Summary

• References

FLAWS IN HISTORIC

ASSESSMENTS

Poor Regulatory Oversight & Guidance

• USEPA – SW 846

• CERCLA RI/FS

• RCRA Corrective Action

• STATE LEAD LPST & Dry Cleaner Programs

Low Ball Assessments to win work by consultants

What Were the Flaws?

• Focus on Delineation of Groundwater

• Incremental Budgets-Cost restrictions

• No focus on Closure Objectives or Options

• Experience of Regulators & Regulated Community

Assessment Objectives

• Protect the Public & Environment

• Focus on Closure

• Optimize Costs – No Not Cheapest!!!

How Do We Do It?

LIFE CYCLE

CONCEPTUAL SITE MODEL

What is a CSM?

CSM is an iterative, “living

representation of a site that

summarizes and helps the project

team visualize and understand all

available information regarding a site”

(ref: EPA 542-F-11-011)

What are the Components?

“Everything We Know about

Historic, Current and Evolving Site-

Operations, Utilities, Contamination,

Geology, Lithology etc.”

Where Do We Start ?

List of Recommended

Components

1- Site History

2- Current & Forecasted Operations/Uses of

Site & Neighbors

3- Source of Contamination & Co-Solvents

4- Nature & Extent of Contamination

5- Lithology, Hydrogeology & Soils

6- Surface & Buried Utilities, Vegetation &

Structures

7- Cleanup Technologies & Options/Limitations

EXERCISE

“Reminder”

Components

1- Site History

2- Current & Forecasted Operations/Uses of

Site & Neighbors

3- Source of Contamination & Co-Solvents

4- Nature & Extent of Contamination

5- Lithology, Hydrogeology & Soils

6- Surface & Buried Utilities, Vegetation &

Structures

7- Cleanup Technologies & Options/Limitations

OIL SPILL at ACTIVE TANK TERMINAL

NEXT TO SHIP CHANNEL

By:

Doug Carvel, P.E

LOCATION MAP

Site History and Former and

Current Ops/Neighbors

1- Filled in Marshlands in the 40-50s, with

dredge spoils from Ship Channel Construction

2- Developed in the 60’s as a Bulk Fuel and

Petrochemical Tank Terminal

3-Neighbors are Ship Channel, and other Bulk

Terminals

4-Projected to be Tank Terminal in the Future

Source of Contamination

1- Stormwater Treatment Sump discharge

line separated

2- Discharged contaminated contact

rainwater from tank berms for unknown

period of time, likely 2-3 years

Lithology & Nature of

Contamination

• Tight Complex Matrices next to &

beneath existing Sump

• Fully Delineated BETX Contamination

(Average 2 mg/L)

• No TPH analytical in Soil or

Groundwater!!!!!!!!!!

• Vadose & Saturated Zone

Contamination both Sorbed & NAPL

• NAPL Insoluble & High Boiling Point

Current Operations

Receptors & Utilities

• Ship Channel

• Active Terminal & Sump

• Flammable Liquids

• Steel Bulkhead with Holes

• Stable water table

• No Buried Utilities, all Overhead

Piping & Conduits

Technology Selection Process

• No Excavation

• No Spark Source Technologies

• No Toxic Chemicals Leaching into Ship Channel

• No Technology that Could Damage Bulkhead

Technology Screening (Cont.)

• Need for Rapid NAPL Treatment: No Bio

• Enhanced Recovery: No Blowers

• Biodegradable Solvent Extraction: OK

• Proximity of Ship Channel: No Surfactants

• Alkaline ISCO: OK; No Acid ISCO

Next Phase:

Technology Screening

• Evaluate Technologies Further Testing & Assessment

• Further Technology Screening Treatability Testing

Solvent Screening

Solvent

Evaluation Factor

Toxicity/

Biodegradable

Effectiveness

with NAPL

Effectiveness with

Sorbed Mass

Biodegradable

Turpene H H H

IPA H E

E

TCE, PCE,

MEK, etc. N H H

Legend: H – highly effective E – effective N – not effective

Chemical Oxidant Screening

ISCO

Technology

By Contaminant Speed

to Treat

NAPL BTEX

Chlorinated

Ethenes

Chlorinated

Ethanes

Chlorinated

Methanes MTBE

Hydro-

carbons

1,4-

Dioxane

Klozur™

Activated

Persulfate

H H H H H H H H

Fenton’s

Chemistry H H E N E H H H

Ozone H H H E E H E E

Legend: H – highly effective E – effective N – not effective

Oxidant Volts(1)

Hydroxyl Radical (OH•) 2.7

Sulfate Radical (SO4•) 2.6

Ozone (O3) 2.4

Sulfate (S2O8-2) 2.1

Hydrogen Peroxide (H2O2) 1.8

Permanganate (MnO4-) 1.7

Chlorine (Cl2) 1.4

Treatment Goals &

Process Optimization

• Goals

- Enhance desorption

- Persistent oxidation

- Maximize oxidant radicals

- Elimination of DNAPL

- No rebound

• In-situ chemical oxidation technologies selected

- Catalyzed hydrogen peroxide (CHP)

- Activated sodium persulfate

• Methods - Solvent and Reagent Recirculation

Overview of Selected

ISCO Technology

Activated Persulfate (simplified activation):

S2O82- 2SO4

- ● SO4- ● + e- + Contaminant

SO42- + CO2 + H2O

Contaminant & Co-Solvents Must Be in Aqueous

Phase & Dissolved in Groundwater to be Treated

Activated Persulfate

• Persulfate can be activated:

- Presence of a transition metal

- Heat (~95oF for benzene)

- Hydrogen peroxide

- High pH

- UV

• NaOH has a heat of hydration of 55 OC

• For sodium persulfate, sodium sulfate is a byproduct

• It has USEPA secondary maximum contaminant level

of 250 ppm

PVC column equipment

Manometer

(1.2m glass tube)

A peristaltic pomp

Top-end plug unit

Three-way stopcock

(PC)

The clear PVC column

(50mm diameter)

Silca sand layer

Silty sand layer

(Oil contaminated soil)

A glass filter &

a PTFE grating sheet

Silca sand layer

The bottom-end plug unit

PTFE tube

(siphon)

Supernatant

Contaminated soil

A PTFE grating sheet

Fluid server

Persulfate Safety

• All oxidizing chemicals require careful handling/use

• Stainless steel preferred

• Other metals cause decomposition

• pH of persulfate solutions decrease over time, & may drop <2

• PPE: eyewear, gloves, chemical resist shoes, respiratory dust

• Store persulfate in cool dry storage area

• Store/process persulfate solutions in vented vessels

Flammability

Health Reactivity

0

1 1

OXY

Initial Application/Field Pilot

• Application of 8 % Solvent to 4 Wells while

Extracting from Center Well followed by pH

adjustment & subsequent Oxidant Application

20 liters/min extraction rate – 10 from lower

zone and 10 from upper zone

16 liters/min total application rate

• 2-day application

Application/Field Pilot

MECX ISCO

Reagent Delivery

MECX Reagent

Distribution Manifold

MECX ISCO Wellhead

MECX Temperature Monitoring

Chemical Storage

Chemical Processing Area

Pre/Post Mass Distribution

DissolvedSorbed

NAPLTotal

0

5000

10000

15000

20000

25000Post

Pre

Overall Total Mass Reduction: 88%

(ppm)

References

• SW-846 Streamlined – EPA530-F-05-002

• SW-846 – Official hard Copy and Amendments

National Technical Information Service (NTIS) US Department of Commerce

5301 Shawnee Road

Alexandria, VA 22312

800.553.NTIS (800.553.6847)

703.605.6000 (sales)

703.605.6900 (fax order)

Outside the continental US, call 703.605.6000

• USEPA – CLU-IN - Optimization Kirby Biggs

Technology Integration and Information Branch

PH: (703) 823-3081 | Email: biggs.kirby@epa.gov

References (cont)

ASTM -

E2531-06e1 - Standard Guide for Development

of Conceptual Site Models

- http://www.astm.org/Standards/E2531.htm

ITRC –

Triad Implementation Guide – May 2007

MECX, Inc.

www.mecx.net

A Service-Disabled Veteran-Owned Small Business

QUESTIONS?

Contact

Doug Carvel P.E.

President

(281) 850-2054 cell

(713) 585-7000 x 7003 office

8864 Interchange Drive

Houston, Texas 77054

doug.carvel@mecx.net