O R C ® T E C H N I C A L B U L L E T I N O - 3 . 2 . 1 1
Slurry Injection MTBE Remediation in Pennsylvania
Figure 1
MTBE, BTEX Slurry Injection Silty Sand 0.6-1.0 ft/day
Contaminants Application Method Soil Type Groundwater Velocity
High levels of MTBE and BTEX in groundwater were reported at a service station in Pennsylvania. Con-tamination was likely due to leakage from a dispenser island and UST. The contaminant plume consisted ofMTBE concentrations ranging up to 15,000 ppb and BTEX concentrations ranging up to 54,000 ppb in anaquifer consisting primarily of silty sand. Groundwater flow direction is to the west at a calculated velocityranging from 0.6 to 1.0 foot per day.
A total of 540 pounds of ORC powder were injected as a slurry via Geoprobe® in the area of the dispenserisland. Monitoring well MW-2, located 60 feet downgradient from the dispenser island, was used to moni-tor the reduction of BTEX and MTBE. A map of the site detailing the treatment area, groundwater flowdirection, and monitoring well location is presented in Figure 1. After approximately six months, MTBEand BTEX levels decreased substantially in MW-2. The decrease in contaminant levels is graphically repre-sented in Figure 2.
NOTE: The data set represented in the following graphs shows that BTEX levels decrease before MTBElevels. The ORC Technical Bulletin entitled “Potential for the Bioremediation of Methyl Tertiary ButylEther (MTBE)” discusses this mechanism in more detail, pointing out that the presence of backgroundhydrocarbons (i.e. BTEX) may interfere with the metabolism of MTBE. Thus, the impact of ORC onBTEX is an important secondary factor in MTBE bioremediation.
Business
Former UWS
Waste Trans.
Building
N
UST
FIELD
GENERAL AREA OF
ORC INJECTION
DISPENSER
ISLAND
0’ 50’ 100’ 150’ 200’
MW-2
MONITORING WELL
GW FLOW
SCALE
83.90
83.80
83.70
83.60
84.00
83.50
GW CONTOUR
Figure 2
0
20000
40000
60000
Par
ts p
er B
illio
n B
TE
X
0
5000
10000
15000
20000
25000
Par
ts p
er B
illio
n M
TB
E0 30 60 90 120 150
Days
BTEX MTBE
Source Treatment in PAReduction in BTEX and MTBE at MW-2
MW-2 60' DG
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