7 pp. / First in a planned series for each county in the state. / Limited information is available to the County Extension offices to address common concerns of water supply in rural Arizona. In addition, in the more metropolitan areas of the state, little is understood about water resources. This project is proposed to provide a ten to twelve page primer on water resources on a county-by-county basis, beginning with Yavapai County.

3 pp. / This is a section of the "Arizona Well Owner's Guide to Water Supply" already peer reviewed and published by CALs - - we are pulling out short topics from the booklet for 'fact sheet' publication and distribution. This is NOT applicable to eXtension as it is Arizona specific and not applicable to anything outside the state. / Arizona has stringent permit requirements for the construction of water wells, but domestic well owners are responsible for repair and maintenance of their own wells to assure a reliable water supply of consistent quality. For the proper maintenance of domestic wells, it is important to have a basic understanding about the different materials that comprise a home water supply system. This fact sheet presents information about Arizona domestic well components, including well casings, well caps, well screens, and pitless adapters; basic materials that combine with a pump to provide water for a household.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

This work addresses the poroelastic effect on the processes involved in hydraulic fracturing and post-fracture production using a finite element based fully coupled poroelastic model which includes a triple system of wellbore-fracture-reservoir. A novel numerical procedure for modeling hydraulic fracture propagation in a poroelastic medium is introduced. The model directly takes into account the interaction of wellbore, hydraulic fracture and reservoir in a fully coupled manner. This allows realistic simulation of near fracture phenomena such as back stress and leak-off. In addition, fluid leak-off is numerically modeled based on the concept of fluid flow in porous media using a new technique for evaluating local pressure gradient. Besides, the model is capable of accommodating the zone of reduced pressure (including intermediate and fluid lag zones) at the fracture front so as to capture the behavior of fracture tip region more realistically. A fully coupled poroelastic model for gas reservoirs has been also developed using an innovative numerical technique. From the results of this study it has been found that fracture propagation pressure is higher in poroelastic media compared to that of elastic media. Also high formation permeability (in the direction normal to the hydraulic fracture) and large difference between minimum horizontal stress (in case of it being the smallest principal stress) and reservoir pressure reduce the rate of fracture growth. Besides, high pumping rate is more beneficial in elongating a hydraulic fracture whereas high viscous fracturing fluid is advantageous in widening a hydraulic fracture. It has been also shown that rock deformation, permeability anisotropy and modulus of elasticity can have a significant effect on fluid flow in a hydraulically fractured reservoir. Furthermore, it has been shown that long stress reversal time window and large size of stress reversal region can be caused by high initial pressure differential (i.e. the difference between flowing bottomhole pressure and reservoir pressure), low initial differential stress (i.e. the difference between maximum and minimum horizontal stresses) and low formation permeability in tight gas reservoirs. By taking advantage of production induced change in stress state of a reservoir, this study has also shown that a refracture treatment, if carried out in an optimal time window, can lead to higher economic gain. Besides, analysis of stress reversal region has depicted that a small region with high stress concentration in the vicinity of the wellbore could impede refracture from initiating at the desired place. Moreover, re-pressurization of the wellbore can result in further propagation of the initial fracture before initiation or during propagation of the secondary fracture.

Published scientific work indicates that residential large diameter drinking water wells are at a higher risk of contamination from surface water impacts than drilled wells. The possibility of a higher incidence of contamination of large diameter wells is attributed to site selection and construction problems such as leaking joints in the well casing, ineffective annular sealant placed between the well casing and the formation, a poorly fitted cover with an access lid that promotes contaminant entry and air entry without adequate air filtration, well location down gradient of septic effluent sources, and depth limitations due to improper equipment used to advance the well which results in shallow wells often situated in topographical lows. In some situations, flaws in the well design were actually deliberate measures intended to capture surface water at sites with low groundwater yield. Historically, residential drinking water well performance studies have focussed on existing wells; however, uncertainty in the actual well construction methods and materials, well age and maintenance efforts have been problematic. A field and laboratory study was completed to assess the performance of several design changes that were thought to improve the integrity of large diameter drinking water wells, and to determine whether one design is more prone to atmospheric and/or surface water contamination than the other. Four large diameter residential wells were installed at a study site in Lindsay, Ontario. Three of these wells are constructed with enhanced construction methods (two using a cement tile casing and one using a galvanized steel casing) and annular sealants, while the fourth was constructed using conventional methods for cement cased wells. The enhanced test wells utilized a sealant between the casing sections, various annular sealants between the formation and the well casing, sanitary waterline connections, and ventilation with air filtration. The well constructed using outdated methods did not have any of these advanced features. An automated water extraction system removed about 875 L/day from each well to mimic residential usage. Routine monitoring, and laboratory and field testing were used to collect pertinent data required for this performance assessment. Routine monitoring involved the visual inspection of the wells, collection of well water elevation, collection of soil temperature profile data, collection and analysis of water samples, and collection of cumulative water volumes purged from the test wells. A biofilm cleaning study and analysis of cement-bentonite grout was conducted in the laboratory while smoke and aqueous tracer tests were conducted in the field. The biofilm cleaning study entailed growing a biofilm on different large diameter well casing materials and applying cleaning methods thought to be practical for cleaning the interior walls of large diameter wells. Different mixtures of cement-bentonite grout were subjected to volume measurements, vertical load bearing capacity analysis, and hydraulic conductivity analysis to determine their suitability as a potential annular sealant. The tracer tests were developed to determine whether pathways for either airborne contaminants or surface water to enter the test wells exist. The test wells were filled with smoke and monitored for potential atmospheric pathways. A tracer solution was infiltrated around the test wells and the interior of the tests wells were monitored for potential pathways for surface water to enter. Bacteriological indicators were detected in all test wells. The smoke tracer tests demonstrated that pathways for airborne contaminants to enter the test wells exist with more pathways observed in the winter than the summer. The aqueous tracer tests highlighted several areas where surface water could enter the test wells if ponding occurred around the well casing. As expected the enhanced test wells performed much better than the conventional test well for both of these tracer tests. The results of the biofilm cleaning study indicated that galvanized steel or fibreglass casing materials were the only materials able to be cleaned effectively. The best method in this study to remove biofilm from casing materials was pressure washing. The results from the cement-bentonite grout investigation indicated that cement-bentonite grout with 5% bentonite would make the most suitable annular sealant as its volume changed the least during curing, it was strong enough to support the load from maintenance efforts, and was the most impervious. The results of this study indicate that large diameter wells constructed with a proper annular sealant, sealant between casing sections and a sanitary waterline connection are less prone to contamination. Monitoring of the test wells should continue as they mature to determine whether this plays a significant role in their ability to prevent contamination of large diameter wells. Smoke tracer tests should be conducted again during the winter to determine if temperature was the cause of increased atmospheric pathways. A field-scale method to remove biofilm from the interior casing wall of large diameter wells should be developed and tested. A field-scale investigation of cement-bentonite grout for use as an annular sealant should be completed. Fibreglass casings can be fabricated as a continuous piece with no seams or joints and hence another well should be constructed and studied using corrugated fibreglass (NSF ANSI 61) casing.

Published scientific work indicates that residential large diameter drinking water wells are at a higher risk of contamination from surface water impacts than drilled wells. The possibility of a higher incidence of contamination of large diameter wells is attributed to site selection and construction problems such as leaking joints in the well casing, ineffective annular sealant placed between the well casing and the formation, a poorly fitted cover with an access lid that promotes contaminant entry and air entry without adequate air filtration, well location down gradient of septic effluent sources, and depth limitations due to improper equipment used to advance the well which results in shallow wells often situated in topographical lows. In some situations, flaws in the well design were actually deliberate measures intended to capture surface water at sites with low groundwater yield. Historically, residential drinking water well performance studies have focussed on existing wells; however, uncertainty in the actual well construction methods and materials, well age and maintenance efforts have been problematic. A field and laboratory study was completed to assess the performance of several design changes that were thought to improve the integrity of large diameter drinking water wells, and to determine whether one design is more prone to atmospheric and/or surface water contamination than the other. Four large diameter residential wells were installed at a study site in Lindsay, Ontario. Three of these wells are constructed with enhanced construction methods (two using a cement tile casing and one using a galvanized steel casing) and annular sealants, while the fourth was constructed using conventional methods for cement cased wells. The enhanced test wells utilized a sealant between the casing sections, various annular sealants between the formation and the well casing, sanitary waterline connections, and ventilation with air filtration. The well constructed using outdated methods did not have any of these advanced features. An automated water extraction system removed about 875 L/day from each well to mimic residential usage. Routine monitoring, and laboratory and field testing were used to collect pertinent data required for this performance assessment. Routine monitoring involved the visual inspection of the wells, collection of well water elevation, collection of soil temperature profile data, collection and analysis of water samples, and collection of cumulative water volumes purged from the test wells. A biofilm cleaning study and analysis of cement-bentonite grout was conducted in the laboratory while smoke and aqueous tracer tests were conducted in the field. The biofilm cleaning study entailed growing a biofilm on different large diameter well casing materials and applying cleaning methods thought to be practical for cleaning the interior walls of large diameter wells. Different mixtures of cement-bentonite grout were subjected to volume measurements, vertical load bearing capacity analysis, and hydraulic conductivity analysis to determine their suitability as a potential annular sealant. The tracer tests were developed to determine whether pathways for either airborne contaminants or surface water to enter the test wells exist. The test wells were filled with smoke and monitored for potential atmospheric pathways. A tracer solution was infiltrated around the test wells and the interior of the tests wells were monitored for potential pathways for surface water to enter. Bacteriological indicators were detected in all test wells. The smoke tracer tests demonstrated that pathways for airborne contaminants to enter the test wells exist with more pathways observed in the winter than the summer. The aqueous tracer tests highlighted several areas where surface water could enter the test wells if ponding occurred around the well casing. As expected the enhanced test wells performed much better than the conventional test well for both of these tracer tests. The results of the biofilm cleaning study indicated that galvanized steel or fibreglass casing materials were the only materials able to be cleaned effectively. The best method in this study to remove biofilm from casing materials was pressure washing. The results from the cement-bentonite grout investigation indicated that cement-bentonite grout with 5% bentonite would make the most suitable annular sealant as its volume changed the least during curing, it was strong enough to support the load from maintenance efforts, and was the most impervious. The results of this study indicate that large diameter wells constructed with a proper annular sealant, sealant between casing sections and a sanitary waterline connection are less prone to contamination. Monitoring of the test wells should continue as they mature to determine whether this plays a significant role in their ability to prevent contamination of large diameter wells. Smoke tracer tests should be conducted again during the winter to determine if temperature was the cause of increased atmospheric pathways. A field-scale method to remove biofilm from the interior casing wall of large diameter wells should be developed and tested. A field-scale investigation of cement-bentonite grout for use as an annular sealant should be completed. Fibreglass casings can be fabricated as a continuous piece with no seams or joints and hence another well should be constructed and studied using corrugated fibreglass (NSF ANSI 61) casing.

Not available / text

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

This work addresses the poroelastic effect on the processes involved in hydraulic fracturing and post-fracture production using a finite element based fully coupled poroelastic model which includes a triple system of wellbore-fracture-reservoir. A novel numerical procedure for modeling hydraulic fracture propagation in a poroelastic medium is introduced. The model directly takes into account the interaction of wellbore, hydraulic fracture and reservoir in a fully coupled manner. This allows realistic simulation of near fracture phenomena such as back stress and leak-off. In addition, fluid leak-off is numerically modeled based on the concept of fluid flow in porous media using a new technique for evaluating local pressure gradient. Besides, the model is capable of accommodating the zone of reduced pressure (including intermediate and fluid lag zones) at the fracture front so as to capture the behavior of fracture tip region more realistically. A fully coupled poroelastic model for gas reservoirs has been also developed using an innovative numerical technique. From the results of this study it has been found that fracture propagation pressure is higher in poroelastic media compared to that of elastic media. Also high formation permeability (in the direction normal to the hydraulic fracture) and large difference between minimum horizontal stress (in case of it being the smallest principal stress) and reservoir pressure reduce the rate of fracture growth. Besides, high pumping rate is more beneficial in elongating a hydraulic fracture whereas high viscous fracturing fluid is advantageous in widening a hydraulic fracture. It has been also shown that rock deformation, permeability anisotropy and modulus of elasticity can have a significant effect on fluid flow in a hydraulically fractured reservoir. Furthermore, it has been shown that long stress reversal time window and large size of stress reversal region can be caused by high initial pressure differential (i.e. the difference between flowing bottomhole pressure and reservoir pressure), low initial differential stress (i.e. the difference between maximum and minimum horizontal stresses) and low formation permeability in tight gas reservoirs. By taking advantage of production induced change in stress state of a reservoir, this study has also shown that a refracture treatment, if carried out in an optimal time window, can lead to higher economic gain. Besides, analysis of stress reversal region has depicted that a small region with high stress concentration in the vicinity of the wellbore could impede refracture from initiating at the desired place. Moreover, re-pressurization of the wellbore can result in further propagation of the initial fracture before initiation or during propagation of the secondary fracture.

abstract: Bioretention basins are a common stormwater best management practice (BMP) used to mitigate the hydrologic consequences of urbanization. Dry wells, also known as vadose-zone wells, have been used extensively in bioretention basins in Maricopa County, Arizona to decrease total drain time and recharge groundwater. A mixed integer nonlinear programming (MINLP) model has been developed for the minimum cost design of bioretention basins with dry wells. The model developed simultaneously determines the peak stormwater inflow from watershed parameters and optimizes the size of the basin and the number and depth of dry wells based on infiltration, evapotranspiration (ET), and dry well characteristics and cost inputs. The modified rational method is used for the design storm hydrograph, and the Green-Ampt method is used for infiltration. ET rates are calculated using the Penman Monteith method or the Hargreaves-Samani method. The dry well flow rate is determined using an equation developed for reverse auger-hole flow. The first phase of development of the model is to expand a nonlinear programming (NLP) for the optimal design of infiltration basins for use with bioretention basins. Next a single dry well is added to the NLP bioretention basin optimization model. Finally the number of dry wells in the basin is modeled as an integer variable creating a MINLP problem. The NLP models and MINLP model are solved using the General Algebraic Modeling System (GAMS). Two example applications demonstrate the efficiency and practicality of the model. / Dissertation/Thesis / Masters Thesis Civil Engineering 2016