May 19, 2012
BACKGROUND
ASSUMPTIONS
TECH SCENARIOS
PARAMETERS
CALCULATIONS
Announcements
Message:
Date:
Welcome
9/7/2011
The Leaking UST Footprint Calculator estimates and compares the greenhouse gas emissions for the five most common remediation technologies used at contaminated underground storage tank sites in California. Results are normalized to short-tons of CO2 emissions. One short-ton is equal to 2,000 pounds. The calculator is pre-populated with average values collected from real leaking UST sites across California. You can use these average values, select a design scenario, or customize inputs to fit the conditions at your site.
The calculator is meant to help cleanup professionals and stakeholders better understand the greenhouse gas emissions of common technologies. It provides a breakdown of where emissions come from and where they can be reduced for remedy optimization.
Sullivan International Group, Inc. designed and built this website with input and funding from the U.S. EPA and the California State Water Resources Control Board. It is a BETA release. Input is welcome. Please submit your comments and suggestions about the Calculator methodology via the “Contact Us” link. If something is not working on the website, use the “Report a Bug” link.
Remediation Technologies
Soil Excavation
Soil Vapor Extraction
Pump and Treat
Multi-Phase Extraction
Monitored Natural Attenuation
Announcement
Excavation
Excavation is digging up contaminated soil so it can be cleaned or disposed of properly in a landfill. The soil is excavated using construction equipment, like backhoes or bulldozers. More information can be found here:
http://www.clu-in.org/download/citizens/excavation.pdf
.
Soil Vapor Extraction
Soil vapor extraction (SVE), also known as "soil venting" or "vacuum extraction," removes contamination, in the form of vapors, from the soil above the water table. Vapors are the gases that form when chemicals evaporate. The vapors are extracted (removed) from the ground by applying a vacuum to pull the vapors out. Additional information is available here:
http://www.epa.gov/oust/cat/SVE1.HTM
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Pump and Treat
Pump and Treat is a common method for cleaning up groundwater. Pumps are used to bring extract groundwater to the surface where it can be treated with granular activated carbon (GAC). More information is available here:
http://www.epa.gov/superfund/health/conmedia/gwdocs/pum_tre.htm
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Multi-Phase Extraction (MPE)
Multi-Phase Extraction (MPE), also known as “dual-phase extraction,” uses a vacuum system to remove various combinations of contaminated groundwater, separate-phase petroleum product, and vapors from the subsurface. The system lowers the water table around the well, exposing more of the formation. Contaminants in the newly exposed vadose zone are then accessible to soil vapor extraction. Once above ground, the extracted vapors or liquid-phase organics and ground water are separated and treated. Additional information is available here:
http://www.epa.gov/oust/cat/dualphas.htm
.
Monitored Natural Attenuation (MNA)...
Monitored Natural Attenuation (MNA) relies on natural processes to clean up or attenuate pollution in soil and groundwater. Natural attenuation occurs at most polluted sites. However, the right conditions must exist underground to clean sites properly. If not, cleanup will not be quick enough or complete enough. Scientists monitor or test these conditions to make sure natural attenuation is working. MNA may be used with other remediation processes as a finishing option or as the only remediation process if the rate of contaminant degradation is fast enough to protect human health and the environment. Additional information is available here:
http://www.epa.gov/oust/cat/mna.htm
.
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Background
The Leaking UST Footprint Calculator estimates and compares the greenhouse gas emissions for the five most common remediation technologies used at contaminated underground storage tank sites in California. Results are normalized to short-tons of CO2 emissions. One short-ton is equal to 2,000 pounds. The calculator is pre-populated with average values collected from real leaking UST sites across California. You can use these average values, select a design scenario, or customize inputs to fit the conditions at your site.
The calculator is meant to help cleanup professionals and stakeholders better understand the greenhouse gas emissions of common technologies. It provides a breakdown of where emissions come from and where they can be reduced.
Sullivan International Group designed and built this website with input and funding from the U.S. EPA and the California State Water Resources Control Board. It is a BETA release. Input is welcome. Please submit your comments and suggestions about the Calculator methodology via the “Contact Us” link. If something is not working on the website, use the “Report a Bug” link."
Scope:
The Calculator considers emissions that result from direct cleanup work, such as electricity generation, transportation to the site, and energy consumed treating water. It does not quantify the carbon footprint of processes associated with the manufacture of materials used in the remediation technology, such as the manufacture of heavy equipment and PVC piping for monitoring wells. All equations and assumptions used in the calculation are documented in this website. If you cannot find something please contact us.
The website is designed to allow you to assess remediation options and identify remedy optimization opportunities for five remediation technologies at one site in 15-30 minutes. Output data and graphics provide CO2 equivalent comparisons of the technologies. The Calculator provides an emissions estimate. Accuracy is affected by several factors, including the calculator methodology and the accuracy of data utilized as key assumptions and coefficients.
The Calculator estimates carbon emissions for the following remediation technologies:
Soil Vapor Extraction (SVE)
Pump and Treat (P&T)
Soil Excavation (Excavation)
Multi-Phase Extraction (MPE)
Monitored Natural Attenuation (MNA)
Disclaimer:
The accuracy of the Calculator’s results have uncertainty based upon many factors including, but not limited to the accuracy of data utilized as key assumptions and coefficients.
Assumptions
Assumptions are employed to determine certain values used in calculations. General Assumptions apply to all sections of the Calculator.
1
All GHG emission calculations are in terms of Short-Tons CO2 Equivalents. Short-Ton = unit of weight equal to 2,000 pounds (0.907 metric ton or 907.18 kilograms). Also called net ton.
2
Larger diameter wells require more drilling time, thus increasing total fuel consumption per well drilled. Experienced professionals within the industry estimated that a 4" well required 15% more time to drill than a 2" well and a 6" well required 30% more time than a 2" well.
3
Emergency response free-product removal is not considered in the calculator.
4
1 day assumes 8 hours of operation.
5
It was assumed that 1 support truck was required to drive to and from the site during all Drilling and/or Direct-push activities (except for Assessment this is asked).
One mobilization/demobilization of equipment and support vehicles was assumed for all non-assessment drilling/boring activities.
6
See links throughout Calculator for details regarding GHG coefficient sources and calculations.
Additional assumptions apply to the specific remediation solutions used in the calculator as follows:
General Assessment
7
All transportation is assumed to be two-way (i.e. roundtrip).
8
General remediation best practices are used and include:
a. Utility clearance - It was assumed 5 pick-up trucks (representing one each for electric, gas, communication, water, and sewer utility locates) were required to drive to and from the site. (2 × 5 × Cgasoline (lb-CO2/gal) × FEpick-up (gal/mile) × dstaff (mile) × Cutility)
b. Borehole clearance - comprised of a diesel powered air knife blower operating for approximately 8 hours. (Cdiesel (lb-CO2/gal) × FEborehole (gal/hr) × 8 (hr/day) × tborehole (days) × Cborehole)
9
Duration of assessment is calculated from the number of borings/wells to be drilled and respective diameters/drilling rates, as well as time required to complete the borehole clearance (assumed to require 1 day per 8 hours). See the
Variables and Parameters worksheet
for further detail regarding drilling rates.
10
Frequency of personnel/staff visits during assessment is 2 per day (average from industry survey results)
11
Average/default soil conditions are SP-SM (poorly graded sands to silty sands). Other soil types range from GP-SP (= poorly graded gravels to poorly graded sand), ML-CL (= silt to clay), and rock/bedrock.
Soils types are converted to a level of effort (LOE) coefficient that is used in subsequent drilling/direct-push calculations. LOE coefficient values are 0.75, 1.0, 1.5 & 3 for GP-SP, SP-SM, ML-CL & Rock/Bedrock, respectively.
Excavation
12
No on-site soil treatment will occur. All contaminated soil will be excavated and transported off-site. Similarly, an equivalent quantity of soil will be hauled to the site for backfill replacement.
13
The number of dump-trucks required to haul contaminated soil is calculated based on excavation dimensions and soil type.
An average dump truck is assumed to haul ~15 tons of excavated soil.
14
Size of excavator is automatically calculated based on soil volume. 100 tons -> 75 hp Excavator, 500 tons -> 100 hp Excavator, 1000 tons -> 150 hp Excavator.
15
Soil densities range from 1.3 to 1.6 tons per yd3 (SP-SM = poorly graded sands to silty sands).
16
The controlling factor for calculating excavation duration is the amount of contaminated soil hauled from the site via dump truck. It is estimated that, on average, 10 loads of contaminated soils are hauled away and 10 loads of clean backfill are hauled to the site each day. Pre-excavation assessment soil boring drilling time is also included in the duration estimation.
17
During excavation test-pit activities, 1 staff pick-up truck is assumed to transport personnel to and from the site daily.
18
Approximately 50 gallons of water are used per ton excavated soil for dust control during excavation activities.
19
Each excavator will be used 8 hours per day throughout the duration of remediation
MPE
20
Trenching and piping installation and removal was considered neglible relative to system operations & maintenance.
21
The energy consumption rate of each system is calculated based on the system size (total horsepower).
It is also assumed each system is operating continuously at maximum power for the entire duration of operation.
X hp * 0.746 (kW/hp) * 8760 (hrs/yr) * 0.003412 (mmBTU/kWh)
22
Off-Gas Carbon Treatment:
a) GAC off-gas discharge treatment is assumed unless an alternative method is selected.
i) 2 to 5 carbon vessels, depending on total horsepower of the system, are replaced annually (via semi-truck).
ii) Size of carbon vessels are calculated based on size of MPE system: If MPE total system horsepower is up to 20 hp -> 500 lb vessels; if MPE total system horsepower is >20 hp and up to 30 hp -> 1,000 lb vessels; if MPE total system horsepower is >30 hp -> 2,000 lb vessels.
iii) Off-gas carbon treatment operation is assumed to operate during 100% of the overall system operations.
b) If Thermal Oxidation or Catalytic Oxidation off-gas treatment is selected, the design flowrate is based on the size of the MPE system. If MPE total system horsepower is up to 20 hp -> 100 scfm; if MPE total system horsepower is >20hp and up to 30 hp -> 200 scfm; and if MPE total system horsepower is >30 hp -> 500 scfm.
i) Off-gas air stream is assumed to have the heat capacity and density of air at 70 degrees F.
ii) The off-gas is heated to 1400 degrees F for ThemOx and to 800 degrees F for CatOx. Heat exchanger efficiency is assumed to be 50%.
23
GAC vessels are assumed for water treatment:
i) 2 to 5 carbon vessels, depending on total horsepower of the system, are replaced annually (via semi-truck).
ii) Calculated based on size of MPE system: If MPE total system horsepower up to 20 hp -> 1,000 lb vessels; If MPE total system horsepower is >20 hp and up to 30 hp -> 2,500 lb vessels; If MPE total system horsepower >30 hp -> 5,000 lb vessels.
iii) Water treatment carbon vessel operation is assumed 100% of the overall system operations.
24
Assumed water is used at 5 gpm and is supplied by water utilities and requires equivalent water treatment as provided by such utilities.
25
Assumed a 300 square foot building is required to house the MPE system.
26
Time required to install full-scale system is 14 days.
27
During abandonment, the average yellow equipment (i.e. crane, excavator, front end loader, etc.) size is assumed to be 125 hp.
28
During the pilot study and installation process, 1 pick-up truck is assumed to transport all personnel to and from the site each day, and 1 semi-truck (or equivalent) is required to transport the MPE system to the site.
SVE
29
Trenching and piping installation and removal was considered neglible relative to system operations & maintenance..
30
The energy consumption rate of each system is calculated based on the system size (horsepower).
It is also assumed each system is operating at maximum power for the entire duration of operation.
X hp * 0.746 (kW/hp) * 8760 (hrs/yr) * 0.003412 (mmBTU/kWh)
31
Off-Gas Carbon Treatment:
a) GAC off-gas discharge treatment is assumed unless an alternative method is selected.
i) 2 to 5 carbon vessels, depending on total horsepower of the system, are replaced annually (via semi-truck).
ii) Size of carbon vessels are calculated based on size of SVE system: If SVE total system horsepower is up to 20 hp -> 500 lb vessels; if SVE total system horsepower is >20 hp and up to 30 hp -> 1,000 lb vessels; if SVE total system horsepower is >30 hp -> 2,000 lb vessels.
iii) Off-gas carbon treatment operation is assumed to operate during 100% of the overall system operations.
b) If Thermal Oxidation or Catalyitic Oxidation off-gas treatment is selected, the design flowrate is based on the size of the SVE system. If SVE total system horsepower is up to 20 hp -> 100 scfm; if SVE total system horsepower is >20hp and up to 30 hp -> 200 scfm; and if SVE total system horsepower is >30 hp -> 500 scfm.
i) Off-gas air stream is assumed to have the heat capacity and density of air at 70 degrees F.
ii) The off-gas is heated to 1400 degrees F for ThemOx and to 800 degrees F for CatOx. Heat exchanger efficiency is assumed to be 50%.
32
Assumed water is used at 5 gpm and is supplied by water utilities and requires equivalent water treatment as provided by such utilities
33
Assumed a 600 square foot building is required to house the SVE system
34
Time required to install full-scale system is 14 days.
35
During the pilot study and installation process, 1 pick-up truck is assumed to transport all personnel to and from the site each day, and 1 semi-truck (or equivalent) is required to transport the SVE system to the site.
36
During abandonment, the average yellow equipment (i.e. crane, excavator, front end loader, etc.) size is assumed to be 125 hp.
37
During the pilot study and installation process, 1 pick-up truck is assumed to transport all personnel to and from the site each day and 1 semi-truck (or equivalent) is required to transport the SVE system to the site.
P&T
38
Trenching and piping installation and removal was considered neglible relative to system operations & maintenance.
39
The energy consumption rate of each system is calculated based on the system size (horsepower).
It is also assumed each system is operating at maximum power for the entire duration of operation.
X hp * 0.746 (kW/hp) * 8760 (hrs/yr) * 0.003412 (mmBTU/kWh)
40
GAC vessels are assumed for water treatment:
i) 2 to 5 carbon vessels, depending on total horsepower of the system, are replaced annually (via semi-truck).
ii) Calculated based on size of P&T system: If P&T total system horsepower up to 20 hp -> 1,000 lb vessels; if P&T total system horsepower is >20 hp and up to 30 hp -> 2,500 lb vessels; if P&T total system horsepower >30 hp -> 5,000 lb vessels.
iii) Water treatment carbon vessel operation is assumed 100% of the overall system operations.
41
Assumed water is used at 5 gpm and is supplied by water utilities and requires equivalent water treatment as provided by such utilities
42
Assumed a 600 square foot building is required to house the P&T system
43
Time required to install full-scale system is 14 days.
44
During abandonment, the average yellow equipment (i.e. crane, excavator, front end loader, etc.) size is assumed to be 125 hp.
45
During the pilot study and installation process, 1 pick-up truck is assumed to transport all personnel to and from the site each day, and 1 semi-truck (or equivalent) is required to transport the P&T system to the site.
Technology Scenarios
Three scenarios cover the general range of the size and complexity of LUST sites. Each scenario has its own set of input values. Conditions for each scenario are listed below.
Please determine the Technology Scenario that best applies to your LUST during use of the Calculator.
Scenario-1: (Least complex site)
Smaller site dimensions, 100 ft x 100 ft (or smaller), up to ~0.25-acre area. Up to eight (8) soil borings & four (4) monitoring wells are needed to complete a site assessment. Additional soil borings and/or monitoring wells may be installed for specific technology applications.
Scenario-2: (Moderately complex site)
Medium site dimensions (larger than Scenario-1), up to 200 ft x 200 ft, ~0.25 to 1.0-acre area. Up to fifteen (15) soil borings & eight (8) monitoring wells are needed to complete a site assessment. Additional soil borings and/or monitoring wells may be installed for specific technology applications.
Scenario-3: (More complex site)
Larger site dimensions (larger than Scenario-2), more than 200 ft x 200 ft, and > 1.0-acre area. Up to twenty (20) soil borings & twelve (12) monitoring wells are needed to complete a site assessment. Additional soil borings and/or monitoring wells may be installed for specific technology applications.
Assessment (General) Scenarios:
Scenario 1:
Eight (8) soil borings with four (4) 2” monitoring wells completed in two (2) drill rig mobilizations to the site.
Scenario 2:
Fifteen (15) soil borings with eight (8) 2” monitoring wells completed in three (3) drill rig mobilizations to the site.
Scenario 3:
Twenty (20) soil borings with twelve (12) 2” monitoring wells completed in three (3), or more, drill rig mobilizations to the site.
MNA Scenarios:
Scenario 1:
Four (4) monitoring wells with semi-annual samples.
Scenario 2:
Eight (8) monitoring wells with semi-annual samples.
Scenario 3:
Twelve (12) monitoring wells with semi-annual samples.
Excavation Scenarios:
Scenario 1:
100 tons of soil excavated and properly disposed. A 100-ton mass of soil is equivalent to 63 yd3 to 77 yd3, based upon a soil density of 1.3 (gravel-sand; GP-SP) to 1.6 (silt-clay; ML-CL), respectively. Clean fill is assumed to replace excavated soil.
Scenario 2:
500 tons of soil excavated and properly disposed. A 500-ton mass of soil is equivalent to 313 yd3 to 385 yd3, based upon a soil density of 1.3 (gravel-sand; GP-SP) to 1.6 (silt-clay; ML-CL), respectively. Clean fill is assumed to replace excavated soil.
Scenario 3:
1,000 tons of soil excavated and properly disposed. A 1,000-ton mass of soil is equivalent to 625 yd3 to 770 yd3, based upon a soil density of 1.3 (gravel-sand; GP-SP) to 1.6 (silt-clay; ML-CL), respectively. Clean fill is assumed to replace excavated soil.
MPE Scenarios:
Scenario 1:
MPE system is assumed to be comprised of eight (8) 4" wells, one (1) 10 hp blower, two (2) 2 hp transfer pumps, one (1) 3 hp transfer pump, one (1) 5 hp air stripper blower, and two (2) 1000 lb carbon vessels.
Scenario 2:
MPE system is assumed to be comprised of twenty (20) 4" wells, two (2) 10 hp blowers, two (2) 5 hp transfer pumps, one (1) 7 hp transfer pump, one (1) 10 hp air stripper blower, and two (2) 2000 lb carbon vessels.
Scenario 3:
Only two scenarios have been pre-populated with input data. Scenario-2 data inputs are used with other Scenario-3 inputs.
P&T Scenarios:
Scenario 1:
P&T system is assumed to be comprised of six (6) 6-8" wells, six (6) 2 hp well pumps, two (2) 2 hp transfer pumps, one (1) 3 hp transfer pump, one (1) 5 hp air stripper, and two (2) 1000 lb carbon vessels.
Scenario 2:
P&T system is assumed to be comprised of fifteen (15) 6-8" wells, fifteen (15) 2 hp well pumps, two (2) 5 hp transfer pumps, one (1) 7 hp transfer pump, one (1) 10 hp air stripper, and two (2) 2000 lb carbon vessels.
Scenario 3:
Only two scenarios have been pre-populated with input data. Scenario-2 data inputs are used with other Scenario-3 inputs.
SVE Scenarios:
Scenario 1:
SVE system is assumed to be comprised of eight (8) 2-4" wells, one (1) 7.5 hp blower, one (1) 1.5 hp transfer pump (for condensate), and two (2) 1000 lb carbon vessels.
Scenario 2:
SVE system is assumed to be comprised of fifteen (15) 2-4" wells, one (1) 15 hp blower, one (1) 2 hp transfer pump (for condensate), and two (2) 2000 lb carbon vessels (vapor carbon).
Scenario 3:
Only two scenarios have been pre-populated with input data. Scenario-2 data inputs are used with other Scenario-3 inputs.
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