NIBW SITE OVERVIEW June 14, 2017 2 SITE HISTORY Volatile organic - PowerPoint PPT Presentation

1 NIBW SITE OVERVIEW June 14, 2017

2 SITE HISTORY • Volatile organic compounds (VOCs) detected in groundwater in 1981 • Placed on National Priorities List (NPL) in 1983 • 1988 Record of Decision (ROD) required extraction and treatment of impacted groundwater to meet MCLs in the middle aquifer (MAU) and lower aquifer (LAU) • 1991 ROD required upper aquifer (UAU) monitoring and soils investigations/cleanups in selected areas

3 SITE HISTORY(continued) • CGTF began treating extracted groundwater in 1994 and providing to Scottsdale • Proactive groundwater remedies implemented at three other facilities • MRTF: northern LAU containment (1997) • Area 7 and Area 12: MAU source control (1999) • Amended ROD (2000) and Amended Consent Decree (2002) • Replaced earlier RODs and CDs • Documented remediation to include proactive remedial actions • NIBW Granular Activated Carbon Treatment Facility (NGTF) completed in 2014 under an Explanation of Significant Differences (ESD)

4 HYDROGEOLOGIC UNITS Three Alluvial Aquifer Units  UAU – Average 150 feet thick  MAU – Average 450 feet thick  LAU – >700 feet thick

5 WESTERN MARGIN

TREATMENT FACILITIES 6 NIBW GAC Treatment Facility • Completed in 2013, with full operations in 2014 • PCX-1 currently treated, with potential to add PG-41 • Granular activated carbon (GAC) treatment • Treated groundwater to COS municipal Central Groundwater Treatment Facility supply or SRP canal • Began operation in 1994 • Owned and operated by City of Scottsdale • Groundwater treated by air stripping • Treated groundwater to Scottsdale municipal supply Miller Road Treatment Facility • Began operations in 1997 • Owned and operated by EPCOR • Wells PV14 and PV15 treated • Groundwater treatment by air stripping • Treated groundwater to EPCOR potable water system Area 12 Groundwater Extraction and Area 7 Groundwater Treatment System Extraction and Treatment • Began operation in 1999 System • Owned and operated by Motorola Solutions • Began operation in 1999 • Groundwater treated by air stripping • Built by Siemens and • Treated water to SRP irrigation canal system operated by Motorola • Ultraviolet oxidation and air stripping treatment • Treated groundwater recharged to UAU aquifer

7 2016 Pumping

8 UAU TCE Oct 2001 – Oct 2016

9 VOC Mass Flux in UAU

10 MAU TCE Oct 2001 – Oct 2016

11 LAU TCE Oct 2001 – Oct 2016

12 NIBW TCE October 2016 Groundwater Plumes

SUMMARY O OF 2016 2016 GRO ROUNDWATE TER EX R EXTR TRACTI TION & & TREA TREATM TMENT TCE Mass Removal Annual Pumpage Annual Pumpage Treatment System Extraction Well (in pounds) (in acre-feet) (in gpm) COS-31 35 1,142 708 COS-71A 130 1,718 1,065 CGTF COS-72 36 1,168 724 COS-75A 393 2,866 1,777 TOTAL 594 6,894 4,274 PV-14 9 3,277 2,032 MRTF PV-15 33 1,904 1,180 TOTAL 42 5,181 3,212 NGTF PCX-1 - TOTAL 561 3,664 2,272 7EX-3aMA 136 155 96 7EX-4MA 184 51 32 Area 7 7EX-6MA 401 236 146 TOTAL 720 442 274 MEX-1MA 105 871 540 Area 12 SRP 23.6E6N 344 1070 664 TOTAL 449 1,941 1,203 OVERALL 2,367 18,123 11,235

NIBW METRICS 14 TCE MASS REMOVED Inception 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 To Date SITE (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (lbs) (pounds) 52,874 CGTF 1,397 1,432 5,535 4,493 4,935 4,858 4,007 3,756 2,795 3,096 2,146 2,013 2,201 1,172 1,476 1,512 1,215 1,054 1,032 1,004 626 525 594 8,119 MRTF 130 168 281 298 573 621 587 628 667 545 524 620 678 592 624 401 73 67 42 1,661 NGTF 264 240 595 561 AREA 7 704 2,384 1,749 1,105 1,922 1,552 1,018 1,030 987 669 802 901 840 1,001 843 762 726 720 19,714 AREA 12 550 940 406 610 317 301 217 328 215 269 249 220 214 181 198 340 414 449 6,418 88,786 TOTALS 1,397 1,432 5,535 4,493 5,065 6,280 7,612 6,209 5,083 5,956 4,586 3,876 4,226 2,919 2,938 3,182 3,014 2,700 2,838 2,712 2,041 2,327 2,366 GROUNDWATER PUMPED Inception 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 To Date SITE (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) (MG) 62,384 CGTF 2,307 1,051 4,053 3,657 3,419 3,436 3,197 3,575 3,170 3,286 3,094 3,175 3,228 1,823 2,502 2,698 2,338 2,697 2,190 1,905 1,559 1,776 2,246 38,317 MRTF 744 1,507 1,504 2,091 1,521 1,994 2,050 2,086 2,063 2,156 1,265 1,275 1,876 2,455 2,799 2,925 2,104 2,110 2,104 1,688 3,174 NGTF 425 479 1,076 1,194 2,950 AREA 7 26 145 142 144 221 216 212 212 208 169 192 185 182 168 134 121 129 144 7,803 AREA 12 139 544 536 456 300 359 369 486 382 504 474 478 479 343 396 419 506 633 114,627 TOTALS 2,307 1,051 4,053 4,401 4,926 5,105 5,977 5,774 5,764 5,857 5,755 5,819 6,082 3,678 4,450 5,239 5,455 6,157 5,627 4,964 4,688 5,592 5,905 AVERAGE TCE CONCENTRATIONS Inception 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 To Date SITE (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) (ug/L) 99 CGTF 71 160 160 144 169 166 147 123 103 110 81 74 80 75 69 66 61 46 55 62 47 35 31 25 MRTF 10 13 16 23 34 35 33 36 36 50 48 39 32 25 25 22 4 4 3 61 NGTF 73 59 65 55 783 AREA 7 3,172 1,926 1,443 899 1,019 842 562 569 556 464 489 571 542 696 737 738 660 585 96 AREA 12 464 202 89 157 124 98 69 79 66 63 62 54 52 62 59 95 96 83 TOTALS 91 71 160 160 120 120 144 149 126 103 119 93 78 81 93 77 71 65 51 59 64 51 49 47

15 SITE STATUS • All vadose (soils) zone remediation programs completed; no remaining threat to groundwater • Area 7 – About 7,000 lbs TCE removed • Area 8 – About 650 lbs TCE removed • Area 12 – About 950 lbs TCE removed  About 9,000 pounds removed from soils • All components of the groundwater pump-and-treat remediation program are functioning properly ( CGTF, MRTF, NGTF, Area 7, and Area 12)  Over 88,000 pounds of TCE removed from groundwater • 2016 Five Year Review found groundwater remedy protective • Formal site protectiveness statement deferred to evaluate potential risk of vapor intrusion and treatment system impacts to ambient air • Vapor intrusion assessment investigations underway

16 October 1990 October 1991 Low er October 1992 October 1993 Alluvium Unit October 1994 October 1995 Plume October 1996 October 1997 October 1998 TCE Concentrations October 1999 October 2000 5 – 50 µg/L October 2001 October 2002 51 – 100 µg/L October 2003 October 2004 > 100 µg/L October 2005 October 2006 October 2007 October 2008 October 2009 October 2010 October 2011 October 2012 October 2013 October 2014 October 2015 October 2016

17 Questions? Thank you!

18 EXTRA SLIDES

19 VAPOR INTRUSION INVESTSIGATIONS • 7 historical source Areas investigated based on 2016 5YR recommendation • 45 Soil Gas Sampling Points installed and sampled • 6 out of 7 Areas had soil gas concentrations below screening levels • Indoor air sampling conducted at Area 7 • Isolated detections above screening levels in two buildings

20 Site History Timeline 2011 Early Original Required & AROD & Remedial Site RODs Voluntary and 2016 Activities Activities & CDs Programs ACD 5YR OU I FS 5YR GMEP OUI ROD FSA 2011 OUII CD 1988 2002 1999 1993 OUII ROD 5YR ESD AROD OUI RI 1991 2016 2012 1984- 2001 ACD OUI CD 1986 2003 1992 1980 1985 1990 1995 2000 2005 2010 2015 2020 1983 1994 2006 NCP List 1997 CGTF Construction MRTF Complete 1994 1981 2013 1999 PV VOC Detection Area 7 and Agreement NGTF in GW Area 12 re: N. LAU

21