PROPOSED ORDER R 7 2019 0018 North Brawley

PROPOSED ORDER R 7 -2019 -0018 North Brawley Geothermal Complex Imperial County Zakary Owens

Proposed Board Order R 7 -2019 -0018 • Discharger’s Request: • Board Order Details: • Regulates the disposal of solid & liquid waste generated from drilling geothermal wells • Temporarily stored in Mud Sumps

What Is Geothermal Energy? Production Well ( ) (Cold Water) Photo Credit: US EPA

Why are Geothermal Permits Unique to the Imperial Valley? • Extensional Tectonic Zone • shallow infiltration of geothermal fluids • Subsidence of Earth’s Surface • Salton Sea Elevation is -225 ft msl Facility Source: https: //www. pe. com/2016/10/07/why-the-discovery-of-a-new-fault-near-the-salton-sea-earthquake-swarm-could-be-important/

Environmental and Logistical Challenges in Geothermal Energy • Viable access • Subsidence • Fluid withdrawal • Hypersaline geothermal brine • 100, 000+ mg/L Total Dissolved Solids • Ocean is only 35, 000 mg/L! • Periodic Maintenance required

North Brawley Geothermal Well Field • R 7 -2007 -0012 • Ormat explores North Brawley • R 7 -2008 -004 • 2008 - Ormat obtains permit for North Brawley Geothermal Power Plant • 2010 - Ormat builds North Brawley Geothermal Power Plant Facility

Site Specific Information: Hovle y Roa d North Brawley Geothermal Power Plant Andre Road • binary flash process • Sudden reduction in Pressure causes vaporization of liquid • Isopentane & Geothermal Brine Stormwater Pond • Water cooling towers • Direct reinjection • No brine pond (aka “closed loop”) • Stormwater pond on site s er oling Tow o C r te a W

A Quick Recap: Isopentane and Hot Water are Flashed Water Cooling Towers No brine pond (aka “closed loop”) Direct North Brawley Geothermal Reinjection Resource Area back into the Depth: 3170 -4501 ft Resource Temperature: 137 -186 °C Photo Credit: US EPA

“Brawley 2” Geothermal Well Field • R 7 -2007 -0012 • 2007 - Ormat explores North Brawley • R 7 -2008 -004 • 2008 - Ormat obtains permit for North Brawley Geothermal Power Plant • 2010 - Ormat builds North Brawley Geothermal Power Plant • Ormat enters 20 -year power purchase agreement with SCE • R 7 -2008 -0032 • 2008 - Ormat explores Brawley 2 • un-dissolved sand discovered in geothermal fluids Facility

Combining Facilities If two facilities can stand alone, as separate and unique, then the facilities may be combined without being considered a major change in operations. Max Allowed: Current Conditions: • 41 wells- North Brawley Geothermal Complex • 36 wells- Brawley 2 Exploration Project • 19 injection wells • 17 production wells North Brawley Well Field Brawley 2 Well Field Combination North Brawley Power Plant 2 x Unique Facilities North Brawley Well Field North Brawley Power Plant 1 x Combined Facility

Well Pads • Mud sumps are located on Well Pads • Mostly located on Agricultural Land • Easement agreements • Limited public access ay hw Hig 1 11

Mud Sumps • Description: • 100’ wide x 250‘ long x 8’ deep • May NOT contain liquid waste • Temporary (1 year) containment of solid drilling waste generated during a drilling event • Current Conditions: • 1 mud sump contains drilling waste • 4 th quarter 2018 Well Head & Associated Infrastructure

What Happens After 1 Year? • Classification of Waste • • • Completed during/shortly after drilling event Nonhazardous • Close in place • Contour to existing landscape Hazardous • Clean closure • Confirmation sampling • Contour to existing landscape

Proposed Board Order R 7 -2019 -0018 • Combine Brawley 2 Well Field (R 7 -2008 -0032) and North Brawley Well Field(R 7 -2008 -008) into North Brawley Geothermal Complex (R 7 -20190018). • Update language to comply with current laws and regulations applicable to the discharge. • Staff Recommends that this Order be adopted.

QUESTIONS?