NIBW Superfund Site. Integration of Groundwater Extraction with a Superfund Remedy

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2 NIBW Superfund Site Integration of Groundwater Extraction with a Superfund Remedy

3 What is the NIBW Site? Deep, alluvial groundwater basin 8 square mile site in urban setting Extensive groundwater contamination in multiple units with complex hydrogeology Listed on NPL in 1983 with EPA lead Multiple PRPs, regulators, water providers and other stakeholders

4 Production Wells Camelback Mountain Chaparral Road Papago Buttes Scottsdale Road Pima Road

5 Camelback Mountain MRTF Remediation Activities Chaparral Road Siemens CGTF Motorola Papago Buttes Scottsdale Road Pima Road

6 NIBW Area Facts of Life Many groundwater producers/users Conflicting water rights and competing interests Historical pumping for drinking water and irrigation uses Wide-spread groundwater depletion and inorganic impacts Contaminant occurrence/movement a result of groundwater pumping and wells

7 Integrating Remediation with Groundwater Resource Management Partner with groundwater users Utilize existing wells, infrastructure, and groundwater pumping Coordinate groundwater extraction for optimum plume management Build-in versatility of treatment systems to meet needs of water users and their demands Manage other water resource issues Wide-spread groundwater depletion and inorganic impacts

8 Big 3 Groundwater Producers City of Scottsdale Local water provider for municipal end use Tied into OU-1 Remedy (required to pump > 6,300 gpm) Paradise Valley Water Company (AAWC) Local water provider for municipal end use Small private water company owned by AWWSC Well field north of Site is main source ( > 12,000 gpm capacity) Salt River Project Regional water provider for municipal/agricultural end use Export groundwater from Scottsdale to West Valley Impacted water supply wells ( > 6,000 gpm capacity) augment surface water supply

9 COS Pump and Treat System Expanded pump and treatment capacity to meet demands Conducted detailed evaluation of fluid flow and contaminant distribution in production wells Replaced existing well for enhanced LAU mass capture Prioritized well pumping/increased monitoring frequency Upgraded treatment system to facilitate use of priority wells and assure safe drinking water Aided evaluation of nitrate and hardness impacts

10 Central Groundwater Treatment Facility (CGTF) 5 existing supply wells 9,450 gpm capacity 3 phases of plant modifications: 1995/98/00 Potable water source 10+ MGD treatment 4,000 + lbs/year TCE removal

11 Paradise Valley Initiative Public/private partnership Phased construction decision process Detailed hydrogeologic characterization tied to remedial design Construction on accelerated schedule Active community participation

12 Arizona-American Water Company Miller Road Treatment Facility 6,300 gpm capacity Versatile piping, plant operations, controls, and discharge Potable water to PVWC and SRP Unique cooperation and water exchange

13 Salt River Project Agreement Provided water supply via NIBW and M52 remedy to replace impacted wells NIBW Pump and Treat Systems (4,000 gpm) OU-2 Pump and Treat System (~ 5,400 gpm) Prioritize well use to achieve better capture/minimize impacts to clean wells Achieves reduced pumping in NIBW and reliable end use at M52

14 Northern LAU Plume Management Focused/consistent groundwater extraction for greatest mass capture Optimize use of treatment system to meet variable demands Reduced pumpage of clean wells outside the plume to minimize impacts and assure containment Allows conjunctive use of surface water to reduce groundwater pumpage of basin

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16 Northern LAU Plume Containment McDonald Road Legend AAWC Wells COS Wells SRP Wells AWC Wells Scottsdale Road Pima Road Chaparral Road Camelback Road LAU PLUME Indian School Road

17 Scottsdale Road Legend Miller Road Treatment Facility McDonald Road AAWC Wells COS Wells SRP Wells AWC Wells PCX-1 LAU Only Pima Road Chaparral Road COS-75A LAU Only COS-75 Abandoned Camelback Road Indian School Road

18 PVWC Water Supply PVWC Wells (6 wells) MRTF 9,600 AF/yr Capacity PVWC End Use 10,600 AF/yr PVWC CAP Water 3,200 AF/yr

19 PVWC/SRP Water Exchange PVWC Wells PCX-1 (SRP Well) 3,200 AF/yr PVWC CAP Water 3,200 AF/yr MRTF 9,600 AF/yr Capacity PVWC End Use 10,600 AF/yr SRP End Use 1,000 KAF/yr

20 CAP/PCX-1 Water Exchange PVWC Wells PCX-1 (SRP Well) 3,200 AF/yr PVWC CAP Water 3,200 AF/yr (Reduced pumping) MRTF 9,600 AF/yr Capacity (via Interconnect Facility) PVWC End Use 10,600 AF/yr SRP End Use 1,000 KAF/yr

21 Lessons Learned Cooperation and coordination with all Stakeholders is essential Expedite source control actions End-use issues are critical Solutions require long-term vision Build-in versatility and flexibility Groundwater resource management must drive the remedy