Gasoline Spill Cleanup

(Volatile Components)

Gasoline Spill Cleanup

(Volatile Components)

RoseAdam Allison

RoseAdam Allison

Problem StatementProblem Statement

To Design a System for Removing Harmful Petroleum Contaminants from a Spill at a Large Fuel Distribution Facility in Central Minnesota

To Design a System for Removing Harmful Petroleum Contaminants from a Spill at a Large Fuel Distribution Facility in Central Minnesota

MethodsMethods

Determine Biodegradation for Natural Conditions

Vapor Extraction System Design to remove volatile components from Soil

Bio-filter to Breakdown Contaminants in Air

Determine Biodegradation for Natural Conditions

Vapor Extraction System Design to remove volatile components from Soil

Bio-filter to Breakdown Contaminants in Air

Natural Attenuation through Biodegradation

Natural Attenuation through Biodegradation

Benzene Breakdown in Natural Conditions

µ = 0.0077 days^-1- First Order Reaction Coefficient of

Benzene- Reaction Pathways:

Benzene Breakdown in Natural Conditions

µ = 0.0077 days^-1- First Order Reaction Coefficient of

Benzene- Reaction Pathways:

Natural Attenuation through Diffusion

Natural Attenuation through Diffusion

Diffusion of Benzene chiefly through air pores in soil

Partition coefficients of other diffusion possibilities unfavorable

Diffusion of Benzene chiefly through air pores in soil

Partition coefficients of other diffusion possibilities unfavorable

Diffusion through a porous media (gasoline through soil) using C/C++ Applications

Total Natural AttenuationTotal Natural Attenuation

€

dMT

dt=dMs

dt+dMw

dt+dMg

dt+dMa

dt= −Aθahm (Ca −C∞) −μMw

Or analytically€

€

CT (t) =

AθahmC∞ +CTi[Aθahm

Vβ+μθwKwg

Kagβ]Ve

−t[Aθ ahmVβ

+μθ wKwg

Kagβ]

[Aθahm

Vβ+μθwKwg

Kagβ]V

€

β =KdKwg

Kag

ρ d +θa +θwKwg

Kag

+θg

Kag

Time for Natural Attenuation

Time for Natural AttenuationNatural Attenuation: Concentration over Time

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 20 40 60 80 100 120 140

Time (years)

Concentration ppb

Soil Vapor ExtractionSoil Vapor Extraction Separates Contaminants from the Soil Air Injection Extraction Wells Increase

System Airflow Vacuum Applied to Underground Wells

To Remove Volatiles as Gas or Vapor

Separates Contaminants from the Soil Air Injection Extraction Wells Increase

System Airflow Vacuum Applied to Underground Wells

To Remove Volatiles as Gas or Vapor

Typical System Schematic:

Diffusion Coefficient in Moist Sand

Diffusion Coefficient in Moist Sand

84.13

0395.0

138.0

0395.0

0000032.0

=

===

==

====

g

aawaag

wgw

gaga

gwgw

wds

C

CKCK

KC

CKC

CKC

CKC

Determining Concentrations:

)(ag

wgwad

ag

wgd

bawg

agbw

eff

K

K

K

KK

DK

KD

Dθθρ ++

+=

))(())(())((r

C

rr

r

D

r

C

rr

r

D

r

C

rr

rK

KD

t

C Teffabaa

wg

agbwT

δδ

δδ

δδ

δδ

δδ

δδ

δδ

=+=

01.0

000083.0

002.0

604.0

21.0

08.0

106.0

==

==

=

==

ag

ws

wg

soil

w

g

a

KK

Kθθ

θθ

Ground-Water PumpGround-Water Pump Ground Water Located

4 ft Below Soil Surface A sump Pump will be

Utilized to Lower the Groundwater Level

Remove as much of the pure gasoline as possible

Ground Water Located 4 ft Below Soil Surface

A sump Pump will be Utilized to Lower the Groundwater Level

Remove as much of the pure gasoline as possible

Typical SVE Flow SystemTypical SVE Flow System

Or analytically

€

Forced AttenuationForced Attenuation

waaT MCQ

dt

dM μ−−=

tK

K

V

Q

TitB

TiTag

wgwa

eCeCtC)(

2)( βμθ

β+−

− ==

)(2 βμθ

β

θθθρβ

ag

wgwa

ag

g

ag

wgwad

ag

wgd

KK

VQ

B

KKK

KKK

+=

+++=

Time for Forced Attenuation

Time for Forced Attenuation

Cleanup time for Forced Attenuation (concentration vs. days)

0

0.2

0.4

0.6

0.8

0 50 100 150 200

Time (days)

Concentration ppb

(mg/m3)

Time for Forced Attenuation

Time for Forced Attenuation

Flow Rate: 76607m^3/day

The system will replace the air filled porosity 1.2 times per day

Assume ROI ~ 1000 m^2/well

15 Wells Required

Flow Rate: 76607m^3/day

The system will replace the air filled porosity 1.2 times per day

Assume ROI ~ 1000 m^2/well

15 Wells Required

2.1)5.5)(000,15(

96315

2

3

=mm

daym

151000

150002

2

=mm

Number of Extraction Wells Required

Number of Extraction Wells Required

The team has determined that 15 wells will be required for the SVE cleanup system

wellperfluenceinofarea

areatreatment

QtV

requiredwells_____

___# ==

ε

Air-Forcing PumpAir-Forcing PumpCenturion II CP-HRV5-6

Specifications:

* 5 Horsepower, Heavy Duty 1800RPM Motor * Champion Splash Lubricated RV15A Pump * Pump RPM 760 * Delivers 16.5CFM @ 175PSI or 19.1CFM @ 125PSI * Centrifugal Unloader for Loadless Starts * Dimensions: L=51 1/2, W=22 3/4, H=47 1/4

With a total required turnover of 76607 m^3 daily with 100 wells, 18.7 cfm is the minimum pump capacity.http://www.allensaircompressors.com/cart.php?target=product&product_id=16386&category_id=266

BiofilterBiofilter

Vapors extracted by the SVE process are typically treated using carbon adsorption, incineration, catalytic oxidation, or condensation. Other methods, such as biological treatment and ultraviolet oxidation, also have been used with SVE systems. The type of treatment chosen depends on which contaminants are present and their concentrations.

Vapors extracted by the SVE process are typically treated using carbon adsorption, incineration, catalytic oxidation, or condensation. Other methods, such as biological treatment and ultraviolet oxidation, also have been used with SVE systems. The type of treatment chosen depends on which contaminants are present and their concentrations.

Governing Transport Equation

Governing Transport Equation

0)(2

2

=−−− ssurfG CCAkdxdC

Vdx

CdD

))42

1

2

1(exp())4

2

1

2

1(exp()( 2

22

1 VADkVD

xaVADkV

D

xaxC surfGsurfG +++++=

Or analytically:

Bio-filter PumpBio-filter Pump

http://www.bullard.com/Respiratory/air_accessories/air_pumps/index.shtml

Image and cfm data Electricity draw data Operating Cost: $0.068 / kw-hr

http://www.bullard.com/Respiratory/air_accessories/air_pumps/index.shtml

Image and cfm data Electricity draw data Operating Cost: $0.068 / kw-hr

Design SpecificationsDesign Specifications

Number of Extraction Wells Biofilter

Number of Extraction Wells Biofilter

SafetySafety

Social ConsiderationsSocial Considerations

Drinking Water MCL EPA Limit is 1ppb EPA suggestion is 0 ppb Beneficial to operate pumps longer

than 6mo. if funds sufficient to lower concentration further.

Drinking Water MCL EPA Limit is 1ppb EPA suggestion is 0 ppb Beneficial to operate pumps longer

than 6mo. if funds sufficient to lower concentration further.

Cost AnalysisCost Analysis

Energy cost of water pump Pump Operating Cost (at $0.068/kw-hr)

$109,572.48 Energy cost of air pump Capital cost of $1,538*100 Capital cost of well drilling

Energy cost of water pump Pump Operating Cost (at $0.068/kw-hr)

$109,572.48 Energy cost of air pump Capital cost of $1,538*100 Capital cost of well drilling

QuestionsQuestions