Sequenced Permeable Reactive Barrier for the Pretreatment of Nitrate and Remediation of Trichloroethene - Permeable Reactive Barrier: Sustainable Groundwater Remediation - page 125

Monitoring wells
1—Regional watertable
2—Multilevel
3—Multilevel
4—Multilevel and Leederville formation

Denitrification
PRB

MWG117

MWG118

ZVI PRB

MWG116

MWG108A,B

MWG102A,B,C

MWG119A,B,C

MWG105A,B,C

C

MWG111A,B,C,D

MWG107A,B,C,D
MWG101A,B,C

MWG112A,B,C,D

MWG104A,B,C

MWG106A,B

MWG110A,B,C,D

MWG100A,B,C
MWG120A,B,C

C'

MWG115

MWG103A,B,C

MWG109A,B,C,D

N

MWG114

0510 meters

MWG113

Section location

FIGURE 7.10
Long-term PRB monitoring network.

The first four monitoring rounds included sampling of wells located along
the plume centerline and downgradient of the PRBs (locations MWG109,
MWG110, MWG112, MWG107, MWG111, MWG115, MWG101, MWG106, and
MWG108) for the following suite of analytes:

• VOCs: including at a minimum chlorinated ethenes, ethanes, and
methanes; benzene; toluene; ethylbenzene; and xylenes
• Major ion chemistry: sulfate, chloride, bicarbonate, calcium, magne-
sium, sodium, potassium, and alkalinity
• Nitrate, nitrite, ammonia, and Kjeldahl nitrogen
• pH, electrical conductivity, TOC, total dissolved solids

The subsequent five monitoring rounds have focused on the B series moni-
toring wells, where the majority of the chlorinated solvent mass has been
detected.

7.8 Groundwater
Groundwater levels upgradient of the remediation system have increased,
resulting in larger hydraulic gradients across the PRB system. Additionally,