NIBW Superfund Site Integration of Groundwater Extraction with a Superfund Remedy

What is the NIBW Site? zDeep, alluvial groundwater basin z8 square mile site in urban setting zExtensive groundwater contamination in multiple units with complex hydrogeology zListed on NPL in 1983 with EPA lead zMultiple PRPs, regulators, water providers and other stakeholders

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

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

NIBW Area “Facts of Life” zMany groundwater producers/users zConflicting water rights and competing interests zHistorical pumping for drinking water and irrigation uses zWide-spread groundwater depletion and inorganic impacts zContaminant occurrence/movement a result of groundwater pumping and wells

Integrating Remediation with Groundwater Resource Management zPartner with groundwater users zUtilize existing wells, infrastructure, and groundwater pumping zCoordinate groundwater extraction for optimum plume management zBuild-in versatility of treatment systems to meet needs of water users and their demands zManage other water resource issues 4Wide-spread groundwater depletion and inorganic impacts

Big 3 Groundwater Producers zCity of Scottsdale yLocal water provider for municipal end use yTied into OU-1 Remedy (required to pump > 6,300 gpm) zParadise Valley Water Company (AAWC) yLocal water provider for municipal end use ySmall private water company owned by AWWSC yWell field north of Site is main source ( > 12,000 gpm capacity) zSalt River Project yRegional water provider for municipal/agricultural end use yExport groundwater from Scottsdale to West Valley yImpacted water supply wells ( > 6,000 gpm capacity) augment surface water supply

COS Pump and Treat System zExpanded pump and treatment capacity to meet demands zConducted detailed evaluation of fluid flow and contaminant distribution in production wells zReplaced existing well for enhanced LAU mass capture zPrioritized well pumping/increased monitoring frequency zUpgraded treatment system to facilitate use of priority wells and assure safe drinking water zAided evaluation of nitrate and hardness impacts

Central Groundwater Treatment Facility (CGTF) z5 existing supply wells z9,450 gpm capacity z3 phases of plant modifications: 1995/98/00 zPotable water source z10+ MGD treatment z4,000 + lbs/year TCE removal

Paradise Valley Initiative zPublic/private partnership zPhased construction decision process zDetailed hydrogeologic characterization tied to remedial design zConstruction on accelerated schedule zActive community participation

Arizona-American Water Company Miller Road Treatment Facility z6,300 gpm capacity zVersatile piping, plant operations, controls, and discharge zPotable water to PVWC and SRP zUnique cooperation and water exchange

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

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

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

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

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

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

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

Lessons Learned zCooperation and coordination with all Stakeholders is essential zExpedite source control actions zEnd-use issues are critical zSolutions require long-term vision zBuild-in versatility and flexibility zGroundwater resource management must drive the remedy