Nutrient Reduction by Use of Industrial Deep Injection Wells, Miami-Dade County, Florida

Transcription

1 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.

2 Presentation Outline Overview Objectives Preliminary Investigations Technical Design Anticipated Challenges

3 Overview

4 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 ( km) 38,381 fire hydrants 126,913 valves

5 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

6 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

7 Overview 2008 Ocean Outfall Legislation Chapter , Laws of Florida Reduce nutrient loading to the ocean Meet Advance Wastewater Treatment (AWT) by Dec 31, 2018, or Reduce cumulative outfall loadings (from ) equivalent to AWT from December 31, 2025, stop using outfall and implement 60% reuse

8 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)

9 Objectives

10 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

11 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 ) equivalent to AWT from December 31, 2025, stop using outfall and implement 60% reuse

12 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

13 Preliminary Investigations

14 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

15 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

16 Preliminary Investigations Documented Deep Geology Caverns in Miami-Dade County

17 Technical Design

18 Deep Exploratory Well Central District Wastewater Treatment Plant Virginia Key

19 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 ,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 Permitted injection capacity is 19.9MGD ~1 MGD Centrate ~12 MGD Scrubber Blowdown ~5 MGD Effluent ~1 MGD Leachate , Potential Injection Zone

20 Geophysical Logging Technical Design Dipole Shear Sonic Nuclear Magnetic Resonance Formation Microimager Neutron Porosity Optical Borehole Imaging

21 Packer Testing Technical Design Obtain discrete water quality data Validate log-derived results Estimate confinement properties Target monitor zones Source: Baski, Inc.

22 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

23 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 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 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) gpm gpm gpm gpm gpm 200 Transmissivity = 4,800 gpd/ft 100 Wellhead Pressure (psi) 900 gpm 800 gpm Injection Time (years) psi Pressure Data After Pressure Drop 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) 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)

24 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 Digester Gas Scrubber Centrate Secondary Effluent Phases Landfill Leachate Nutrient Reduction - Nitrogen averaged annual 6.3 million lbs Technical Design

25 Challenges

26 Challenges Large Diameter Boreholes Largest diameter borehole (46-inches) in Florida to a depth of 2,780 feet bls

27 Core Analysis Challenges

28 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?

29 Feet below land surface (bls) Challenges Temporary Steel Casing Installation Base of USDW at 1,360 bls Boulder Zone Sub-Floridan Confinement Zone Potential Injection Zone

30 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 Ammonia-N Magnesium Total P Struvite Saturation Index Precipitation and Plugging Potential - Bench Scale Tests Blended waste streams Blended injectate with ambient aquifer water of injection zone

31 Challenges Permeability within Cretaceous Aged Formation Permeability/Transmissivity Fractures/Fissures Geochemistry Formation Native Water

32 Hydrocarbon Show Challenges

33 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.

34 Questions? For further project or technical information contact: Virginia Walsh and Ed Rectenwald

35 Thank You

36 REALLY LARGE SPIDERS Challenges