printed by www.postersession.com Investigating Microbially Induced Calcite Precipitation for Fracture Permeability Reduction in Rocks Nicholas Bucci, Huijie Lu PhD, Ehsan Ghazanfari PhD. Civil and Environmental Engineering ABSTRACT APPARATUS RESULTS PROCEDURE Barrett Research Scholarships Microbially Induced Calcite Precipitation (MICP) is a bio- geochemical process that produces calcium carbonate precipitation within a pours media matrix such as soil, or bedrock. Preventing contaminant migration via fracture networks in bedrock is extremely important for preserving our precious groundwater resources. MICP offers an attractive alternative method for permeability reduction to traditional grouting/cementation technologies due to its low viscosity reagents and low-pressure application technique. The effectiveness of MICP for rock fracture sealing and permeability reduction is being comprehensively evaluated for the distribution patterns of CaCO3 precipitation, and the resistance of precipitates to long-term persistent changes in temperature, pressure, and groundwater flows in subsurface environments. This research is exploring and developing the necessary laboratory methodologies, apparatuses, and procedures required to generate accurate data in support of MICP use in situ. AKNOWLEDGEMENTS Effluent Stand Core Holder Core Holder Pipe Clamp Influent Steel Wire Effluent Collection Fractured Core Stand Clamp Viton Jacket Syringe Pump • Pre - MICP Computed Tomography Scan: Skyscan 1173 High Energy Micro - CT • Vacuum Chamber Saturation • Pre - MICP Constant Head Hydraulic Conductivity Test ASTM D5084 - 10 = ∆∗ ∗∆ℎ∗∆ • MICP treatment 1 bacterial broth flush (Sporosarcina Pasteurii) 2 reagent flushes ( 1M CO(NH2)2 + 1M CaCl2(2H2O) + 1000mL H2O) • Post - MICP Computed Tomography Scan: • Post - MICP Constant Head Hydraulic Conductivity Test • CT Image Analysis • Effluent Concentration Analysis • Break down apparatus, visually observe the rock core . Lucas Howard, Robert Caulk, Max Graves, Andrea Pearce, Joan Rosebush, Sara Dorr, Austin Grant, Kira Kelley, Anna Waldron • The test apparatus was loosely modeled after an Autolab 1500 tri-axial cell, and optimized for the needs of this research. • Top and bottom core holders were fabricated from plastic rather than expensive and excessively durable titanium or aluminum. • Fluid confining pressure was removed due to low pressure reagent flow • High resolution cross sectional images were generated using a Skyscan 1173 High Energy Micro-CT scanner. A software uses data collected from penetrative X-rays with complex algorithms which allows these cross sections to be created. • Small changes in fracture aperture are visible at this printed resolution, however the images must be digitally observed at full resolution and zoom in order to begin volumetrically quantifying the precipitation within the fracture. * This research is ongoing CONTAMINANT MIGRATION? Groundwater contaminants can originate from septic tanks, nuclear waste disposal, and anything in between. These contaminants easily migrate through shallow soils and into bedrock fracture networks until ending up in a groundwater resources that may end up being consumed by humans. • A constant head Hydraulic Conductivity Test was performed in accordance to ASTM D5084-10 on the first sandstone rock core before and after MICP treatment in order to quantify the changes in permeability that occurred. • The test involves flowing water through the rock core by means of head pressure and recording the effluent flow rate. Three trials were performed to ensure results were precise and to calculate a more accurate average value. K value: Pre MICP = (9.5452 +/- stdev)*− m/s Post MICP = (1.5355 +/- stdev)*− m/s • Preliminary results suggest permeability reductions as high as 84% after being treated with MICP.