GWPC September 27, 2015 Nutrient Reduction by Use of Industrial Deep Injection Wells, Miami-Dade County, Florida Virginia Walsh, PhD, P.G. Miami-Dade Water and Sewer Department Ed Rectenwald, P.G. MWH Americas, Inc.
Presentation Outline Overview Objectives Preliminary Investigations Technical Design Anticipated Challenges
Overview
Miami-Dade Water and Sewer Department (MDWASD) Overview Overview Largest water and sewer utility in Florida, serving more than 2.2 million residents Water System: 3 large regional and 5 small water treatment plants Supplying an average of 304 million gallons per day 90% of the County s public water supply Per capita water use 137 gpcd 100 water supply wells Biscayne Aquifer Floridan Aquifer Aquifer Storage and Recovery 7,918 miles of pipes (12.740 km) 38,381 fire hydrants 126,913 valves
MDWASD Overview Overview Wastewater System: 3 wastewater treatment plants 2 ocean outfalls (3 and 7 miles from coast) and 21 deep injection wells (~2,500 ft depth) Collecting, treating, and disposing 316 MGD 6,292 miles of mains and laterals 1,042 sewer pumps stations (operated) Reusing 10.2 MGD
Overview Ocean Outfalls Northwest Wellfield West Wellfield South West Wellfield Snapper Creek Wellfield & Wellfield & Wellfields Miami Springs Wellfields MDWASD Water & Wastewater Treatment Facilities & Wellfield & Wellfield & Wellfield Deep injection wells & Wellfield & Wellfield Wellfields
Overview 2008 Ocean Outfall Legislation Chapter 2008-232, Laws of Florida Reduce nutrient loading to the ocean Meet Advance Wastewater Treatment (AWT) by Dec 31, 2018, or Reduce cumulative outfall loadings (from 2008-2025) equivalent to AWT from 2018-2025 December 31, 2025, stop using outfall and implement 60% reuse
Overview Current deep injection well Boulder Zone (within the FAS) Upper Cretaceous Formations - Potential Alternative to Lower Floridan Aquifer System Injection Anhydrite confining units (not carbonate units) Potential disposal zones within fractured interval (not in the FAS)
Objectives
Exploratory Well Objectives Objectives Permit as a Class V Exploratory Well Perform Standard and Petrophysical Geophysical Logs, Testing, and Coring Analyze for sufficient confinement above the Boulder Zone Analyze the sub-floridan confinement above the permeable Cretaceous Formations Analyze for adequate injection zone within Cretaceous Formations to approximately 10,000 feet bls Complete injection well within the Boulder Zone, Permit as Class I Industrial with Dual-Zone Monitor Well Preliminary Evaluation and Site Characterization for future disposal into the permeable Cretaceous Formations Reduce nutrient loading
If build AWT for nutrient removal 2018: 59,874,077 lbs Compliance with Ocean Outfall Legislation Centrate Deep injection well 2016: 60,015,437 lbs Reduce nutrient loading to the ocean Meet Advance Wastewater Treatment (AWT) by Dec 31, 2018, or Reduce cumulative outfall loadings (from 2008-2025) equivalent to AWT from 2018-2025 December 31, 2025, stop using outfall and implement 60% reuse
Objectives Virginia Key Landfill Interdepartmental Agreement with Miami-Dade Water and Sewer and Public Works and Waste Management to dispose of groundwater remediation leachate into adjacent Central District Plant Deep Injection Wells
Preliminary Investigations
Preliminary Investigations Preliminary seismic studies at Virginia Key in collaboration with USGS prior to drilling USGS Carbonate Aquifer Characterization Laboratory Davie, FL Seismic profiling at CDWWTP Miami-Dade County USGS PROVISIONAL DO NOT CITE
Preliminary Investigations Documented Deep Geology Caverns in Miami-Dade County Well 6 Central District WWTP Rebecca Shoal Reef Possible permeable zones for injection Well 52 Well 41 Miami-Dade CDWWTP Injection Well
Preliminary Investigations Documented Deep Geology Caverns in Miami-Dade County
Technical Design
Deep Exploratory Well Central District Wastewater Treatment Plant Virginia Key
Technical Design CDWWTP IW-1 Class V Injection Well Design Feet below land surface (bls) 0 Well IW-1 Actual Casing Depths to Date 74-inch Steel to 73 feet bls 66-inch Steel to 300 feet bls 56-inch Steel to 1,060 feet bls 46-inch Steel to 2,090 feet bls 36-inch Steel to 2,780 feet bls Well IW-1 Anticipated Casing Depths 24-inch FRP to 2,780 feet bls 400 800 1200 1600 2000 2400 2800 3200 3600 4000 4400 4800 5200 2,780 3,150 Base of USDW at 1,360 bls Boulder Zone Sub-Floridan Confinement Zone Well IW-1 Injection Zone 2,780 feet to 3,150 feet bls 5600 6000 6400 Permitted injection capacity is 19.9MGD ~1 MGD Centrate ~12 MGD Scrubber Blowdown ~5 MGD Effluent ~1 MGD Leachate 6800 7200 7600 8000 8400 8800 9200 9600 10,000 10000 Potential Injection Zone
Geophysical Logging Technical Design Dipole Shear Sonic Nuclear Magnetic Resonance Formation Microimager Neutron Porosity Optical Borehole Imaging
Packer Testing Technical Design Obtain discrete water quality data Validate log-derived results Estimate confinement properties Target monitor zones Source: Baski, Inc.
Technical Design FRP Injection Tubing Installation Fiberglass Reinforced Plastic (FRP) injection tubing is installed with threaded connections and properly torqued by a Make-up Service Company
Technical Design Complex Injection Capacity Evaluations Need to understand buoyancy effects during testing. Injection zone TDS could be 300,000 mg/l Injectate TDS will be 1,000 mg/l. Need to properly analyze buoyancy effects in testing data sets. Goal is to predict injection capacity and wellhead pressure. 600 550 500 450 400 350 300 250 200 150 Observed Step 3 Wellhead Pressure 100 Calculated Wellhead Pressure (P) Calculated Wellhead Pressure (P+B) 50 Calculated Wellhead Pressure (P+B+F) Calculated Wellhead Pressure (P+B+F+T) Step 3 = 1,280 gpm for 5.94 hours 0 0 1 2 3 4 5 6 7 Notes: P = Permeability F = Friction Losses Time of Step 3 Injection (hours) B = Buoyancy T = Turbulent Flow Effects Wellhead Pressure (psi) 270 psi Estimated Wellhead Pressure (psi) 1000 900 800 700 750 gpm 600 700 gpm 500 600 gpm 400 500 gpm 300 400 gpm 200 Transmissivity = 4,800 gpd/ft 100 Wellhead Pressure (psi) 900 gpm 800 gpm 0 10 20 30 40 50 Injection Time (years) 250 240 230 220 210 200 54 psi 190 180 170 160 150 140 130 120 110 100 90 Pressure Data After Pressure Drop 80 70 60 50 40 Observed Step 2 Wellhead Pressure Calculated Wellhead Pressure (P) 30 Calculated Wellhead Pressure (P+B) 20 Calculated Wellhead Pressure (P+B+F) 10 Step2 = 715 gpm for 5.16 hours Calculated Wellhead Pressure (P+B+F+T) 0 0 1 2 3 4 5 6 7 Notes: Time of Step 2 Injection (hours) P = Permeability F = Friction Losses B = Buoyancy T = Turbulent Flow Effects Wellhead Pressure Permit Limit to be Tested (667 psi) Potential Retest Wellhead Pressure Limit 400 gpm Wellhead Pressure (P+B+F+T) 500 gpm Wellhead Pressure (P+B+F+T) 600 gpm Wellhead Pressures (P+B+F+T) 700 gpm Wellhead Pressure (P+B+F+T) 750 gpm Wellhead Pressure (P+B+F+T) 800 gpm Wellhead Pressure (P+B+F+T) 900 gpm Wellhead Pressure (P+B+F+T)
Conceptual Diagram of Stream Characterization Blended Wastestream ~1 MGD Centrate ~12 MGD Scrubber Blowdown ~5 MGD Effluent ~1 MGD Leachate Ammonia-N Total P Wastestream mg /L mg /L Digester Gas Scrubber 1 10.8 2.9 Digester Gas Scrubber 2 18.9 3.1 Centrate 868.5 60.35 Secondary Effluent 20.6 1.65 Phases Landfill Leachate 44.3 0.44 Nutrient Reduction - Nitrogen averaged annual 6.3 million lbs Technical Design
Challenges
Challenges Large Diameter Boreholes Largest diameter borehole (46-inches) in Florida to a depth of 2,780 feet bls
Core Analysis Challenges
Cementing Large diameter mudded borehole 66 inch diameter borehole to 1,070 ft BLS Pilot hole vs. Reamed hole 5? 15 stages to back plug pilot hole from 3,500 ft BLS 56 stages to cement in 36 in steel casing from 2,780 ft BLS 8?
Feet below land surface (bls) Challenges Temporary Steel Casing Installation 0 400 800 1200 1600 2000 2400 Base of USDW at 1,360 bls 2800 3200 3600 4000 4400 Boulder Zone Sub-Floridan Confinement Zone 4800 5200 5600 6000 6400 6800 7200 7600 8000 8400 8800 9200 9600 10000 10000 Potential Injection Zone
Challenges Formation Plugging and Precipitation Analysis Chemical Characteristics - Desktop Evaluation Preliminary Blended Waste Stream Evaluation Preliminary Blending of Combined Waste Stream with Groundwater Struvite NH 4 MgPO 4 6H 2 Blending Scenario 1 Blending Scenario 2 Parameters mg /L mg /L ph 6.77 6.41 Ammonia-N 43.26 21.94 Magnesium 66.85 67.10 Total P 3.39 1.92 Struvite Saturation Index 0.006096 0.0004909 Precipitation and Plugging Potential - Bench Scale Tests Blended waste streams Blended injectate with ambient aquifer water of injection zone
Challenges Permeability within Cretaceous Aged Formation Permeability/Transmissivity Fractures/Fissures Geochemistry Formation Native Water
Hydrocarbon Show Challenges
Challenges Corrosive Deep Saline Groundwater TDS could be 300,000 mg/l High H 2 S concentrations Potential permanent damage to drill pipe from long term exposure. Potential damage to geophysical logging equipment. Potential surficial aquifer contamination from spillage of super saline brine on ground.
Questions? For further project or technical information contact: Virginia Walsh walshv@miamidade.gov and Ed Rectenwald edward.rectenwald@mwhglobal.com
Thank You
REALLY LARGE SPIDERS Challenges