Moffett Base-Wide Groundwater Update, September 10, 2009

Former NAS Moffett Field

September 10, 2009 - Moffett RAB MeetingGroundwater Program Update

Presented by Julie Crosby-Brooks

2

Presentation Overview

• Basewide groundwater• 2008 annual groundwater report results• 2009 groundwater elevation measurements

• Site 26 pilot test update• EHC injection complete• Groundwater sampling in progress

• Site 28 pilot test update• Pilot test approach

3

Basewide Groundwater - Topics

2008 annual groundwater report submitted in June 2009• November and December 2008 groundwater sampling• March and November 2008 groundwater elevation measurements• WATS operation summary• Report highlights and conclusions

2009 groundwater elevation measurements

4

Basewide GW - Plumes

2007 TCE Plume 2008 TCE PlumeSite 28

TCE GW Plumes

Upper Portion of the A Aquifer

N

5

Basewide GW - Plumes cont.

2008 TCE PlumeSite 26

TCE GW Plumes

Upper Portion of the A Aquifer

2007 TCE Plume

N

6

Basewide GW - WATS

West-side Aquifers Treatment System (WATS) 2008 operation summary• Up-time: 98.9% • Treated and discharged over 36 million

gallons of water• Removed approximately 365

pounds of volatile organic compounds (VOCs)• 96% of mass removed is TCE

and DCE• Submitted NPDES permit

renewal January 2009• Existing permit is effective in

interim• New permit – 10/2/09

7

Basewide GW Report

2008 annual groundwater report highlights• Site 28 – collected samples from more wells than previous

year, better definition of plume boundary• Site 26 – pilot test on-going

2008 annual groundwater report conclusions• Site 28 - plume generally stable, overall decreasing VOC trend,

groundwater flow continues to be to the north• Site 26 – plume generally stable, overall decreasing VOC trend,

groundwater flow continues to be to north - northwest

8

Basewide GW 2009 Work

N

2009 performed:

Collected basewide groundwater elevation measurements in March 2009

2009 planned/in progress:

Well maintenance (locks, bolts, etc.) at wells noted as having deficiencies

Basewide GW sampling in November & December

Basewide GW elevation measurements in November

Site 26 Potentiometric Surface Map

9

Site 26 Pilot Test Status

Background• Objective is to evaluate the effectiveness of EHC to reduce VOC

contamination at Site 26– Collect site specific data– Verify ability to cost-effectively reduce VOC contamination to

below ROD cleanup levels in a reasonable amount of time

Approach • Inject EHC at higher-concentration lobe near Hangar 3• Collect groundwater samples to evaluate contaminant degradation

(baseline, one-month, and quarterly)• Collect performance boring samples to visually confirm radius of

EHC injection• Summarize and evaluate in final pilot test/treatability study report

10

Site 26 Pilot Test - Location

Note – inset location not to scale

11

Site 26 Pilot Test - Location

12

Site 26 Pilot Test Status cont.

Insert a graph or two showing concentration over time

13

Site 26 Pilot Test Status cont.

Preliminary results and trends• PCE and TCE destroyed to < MCLs at some treatment zone wells• DCE concentrations increasing• VC – no big change• Performance borings show that EHC was distributed to at least 7

feet from injection point over 80-90% of the vertical profile• Complete dechlorination evident – ethene and ethane production

14

Site 26 Pilot Test Status cont.

Preliminary conclusions• EHC appears to be effective at completely reducing VOCs to

innocuous chemicals based on ethane and ethene concentrations• DCE is increasing

Path Forward• Finish quarterly sampling• Submit final report that evaluates data and recommends path

forward

15

Site 28 Pilot Test Approach

Background• VOC plume commingled with contamination from MEW and NASA

– Began preparation of regional Feasibility Study (FS)– Several parties are conducting pilot tests to augment FS

Approach • Additional characterization of potential DNAPL areas

– Membrane Interface Probe (MIP) sampling in 3 areas – Navy, EPA, WB, Shaw evaluate data & trends

• Inject substrate (EHC?) to reduce VOC concentrations• Groundwater sampling to evaluate effectiveness• Final report

16

Questions?