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: [email protected]
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
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