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Hydrologic Cycle/Water Supply Aquifers/Properties Well Construction Waterworks Operations WQT 111 Lecture 1 http://ga.water.usgs.gov/edu/watercycle.htmlhttp://ga.water.usgs.gov/edu/watercycle.html Albany and Purdue http://www.purdue.edu/dp/envirosoft/private/src/main.htm
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Objectives Parts the Hydrologic Cycle Aquifer Types Porosity vs. Permeability Water Sources and Supply Groundwater Problems Well Construction and Maintenance The objectives of today’s lecture are to learn the basics of:
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Sources of Drinking Water Surface water Ground water Desalinated sea water Rain water Surface water Ground water Desalinated sea water Rain water
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Many sources of water are directly suitable for drinking purposes without treatment? 1.True 2.False 1.True 2.False
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Source waters include these two broad categories 1.Surface water and ground water 2.Reservoirs and wells 3.Reservoirs and ground water 4.Flowing water and stagnant water 1.Surface water and ground water 2.Reservoirs and wells 3.Reservoirs and ground water 4.Flowing water and stagnant water
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The Drinking Water Cycle Water System Distribution System Sewer Lines Wastewater Plant Discharge Homes or Businesses Septic System Infiltration Source (aquifer, lake, etc.)
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Distribution of Earths Water
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Water For Human Consumption 98% of available fresh water for human use is groundwater We use 100 gal/day per person
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Water For Human Consumption 50% of US population (municipal water systems) 45-50% of US population groundwater 50% of US population (municipal water systems) 45-50% of US population groundwater
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The mineral content and water quality of a particular well is usually pretty consistent. 1.True 2.False 1.True 2.False
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What percentage of the water used in the United States comes from underground sources? 1.45% 2.30% 3.60% 4.90% 1.45% 2.30% 3.60% 4.90%
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Nearly 95 percent of the rural population of the US relies on ground water. 1.True 2.False 1.True 2.False
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It is estimated that daily water usage in the U.S is 88 billion gallons per day, two thirds of which is used for crop irrigation. 1.True 2.False 1.True 2.False
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Hydrologic Cycle Water moves from earth to sky (evaporation and transpiration) Water vapor forms tiny droplets (condensation=clouds) Water falls back to earth (precipitation) Water on the earth penetrates the ground or runs off the surface (infiltration, percolation, surface runoff) Water moves from earth to sky (evaporation and transpiration) Water vapor forms tiny droplets (condensation=clouds) Water falls back to earth (precipitation) Water on the earth penetrates the ground or runs off the surface (infiltration, percolation, surface runoff)
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Evapotranspiration Recharge Ground Water Ground Water / Surface Water Interaction Ground Water / Surface Water Interaction Stream Lake Precipitation Plant Uptake Lake Surface Runoff Riparian Zone Wetland
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Hydrologic Cycle http://ga.water.usgs.gov/edu/watercycle.html (solid to gas)
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Ocean Evaporation Evapo-transpiration runoff Water Supply Discharge treated water Salt Water Intrusion Aquifer Infiltration Recharge Evaporation Extraction Precipitation Evaporation/ET Surface Water Groundwater Soil moisture Infiltration (Art) Extraction Return flow Treated water Aquifer intrusion Soil moisture Soil moisture Detailed Hydrologic Cycle Kennedy 2003
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Condensation http://ga.water.usgs.gov/edu/watercycle.html
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Evaporation http://ga.water.usgs.gov/edu/watercycle.html
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Transpiration http://ga.water.usgs.gov/edu/watercycle.html
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Infiltration http://ga.water.usgs.gov/edu/watercycle.html
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Water Table zone of aeration (vadose) = air and water in pores (unsaturated) zone of saturation = water only in pores groundwater = water beneath soil and above bedrock zone of aeration (vadose) = air and water in pores (unsaturated) zone of saturation = water only in pores groundwater = water beneath soil and above bedrock
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Ground Water UNSATURATED ZONE Ground Water UNSATURATED ZONE WATER TABLE ZONE OF SATURATION
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Aquifer Types
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Aquifers and Wells
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Artesian wells are defined as 1.Having water under a pressure greater than atmospheric which causes the water to rise 2.Being located in an aquifer more than 200 feet deep 3.Any well used to pump high quality drinking water 4.Wells completed less then 25 ft below the ground 5.This designation is just a clever marketing ploy as it applies to all wells 1.Having water under a pressure greater than atmospheric which causes the water to rise 2.Being located in an aquifer more than 200 feet deep 3.Any well used to pump high quality drinking water 4.Wells completed less then 25 ft below the ground 5.This designation is just a clever marketing ploy as it applies to all wells
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Confined Aquifer
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Porosity and Permeability porosity = percent pore space in sediment or rock permeability = capability of a substance to allow the passage of water –depends on porosity and connectivity of pores or fractures porosity = percent pore space in sediment or rock permeability = capability of a substance to allow the passage of water –depends on porosity and connectivity of pores or fractures
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Porosity and Permeability high porosity materials: –clay, sand, well sorted gravel low porosity materials –granite, gabbro, metamorphic rocks –may have high permeability due to fractures high porosity materials: –clay, sand, well sorted gravel low porosity materials –granite, gabbro, metamorphic rocks –may have high permeability due to fractures
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Porosity and Permeability
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Clay Porosity and Permeability Clay is a high porosity material!!! Clay is a low permeability material!!! Clay is a high porosity material!!! Clay is a low permeability material!!!
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Porosity may be defined as 1.The percentage of open space or voids in a particular soil 2.The ratio of filtered to reject water for a sand filter 3.The number of wells sunk per area into a particular aquifer 4.None of these is correct 1.The percentage of open space or voids in a particular soil 2.The ratio of filtered to reject water for a sand filter 3.The number of wells sunk per area into a particular aquifer 4.None of these is correct
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Limestone has more porosity than clay? 1.True 2.False 1.True 2.False
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As groundwater moves through the soil, this type of material may be removed as the soil behaves like a natural filter. 1.Suspended material 2.Dissolved material 3.Salts 4.Ammonia and other nitrogen compounds 1.Suspended material 2.Dissolved material 3.Salts 4.Ammonia and other nitrogen compounds
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Specific yield may be defined as: 1.The amount of water that a particular volume of rock or soil will produce when drained by gravity. 2.The amount of water that a particular well produces when drained by gravity. 3.The amount of water that a particular well produces when pumped forceably. 4.The amount of water that may be squeezed from a volume of rock or soil with a Vadose press. 1.The amount of water that a particular volume of rock or soil will produce when drained by gravity. 2.The amount of water that a particular well produces when drained by gravity. 3.The amount of water that a particular well produces when pumped forceably. 4.The amount of water that may be squeezed from a volume of rock or soil with a Vadose press.
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How much water is produced by a given well depends on which of the following factors? 1.The aquifer 2.The pump 3.The well 4.All of the above 1.The aquifer 2.The pump 3.The well 4.All of the above
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Well Construction Wells should be at least 5 ft from any building Easy to access for repair and maintenance Typically casing extends 1 to 2 feet above the surrounding land Properly fitted pump and pipes (to handle demand) Proper gravel pack and well completion Disinfect w/ 100 mg/L available chlorine Wells should be at least 5 ft from any building Easy to access for repair and maintenance Typically casing extends 1 to 2 feet above the surrounding land Properly fitted pump and pipes (to handle demand) Proper gravel pack and well completion Disinfect w/ 100 mg/L available chlorine
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Well/Pump Parts Properly fitted pump –well pump pedestal- supports the weight of the pumping unit. –Well pump motor base seal -watertight seal between the motor base and the concrete support pedestal. –well pump blow-off -remove first water (usually sandy) pumped at start-up –well casing vent (3”)- air enters well during drawdown to prevent vacuum conditions. Vents excess air during well recovery period. –Air-release vacuum breaker valve (125 psi) - Permits discharge of air in column pipe during start-up and admits air during shutdown. Properly fitted pump –well pump pedestal- supports the weight of the pumping unit. –Well pump motor base seal -watertight seal between the motor base and the concrete support pedestal. –well pump blow-off -remove first water (usually sandy) pumped at start-up –well casing vent (3”)- air enters well during drawdown to prevent vacuum conditions. Vents excess air during well recovery period. –Air-release vacuum breaker valve (125 psi) - Permits discharge of air in column pipe during start-up and admits air during shutdown.
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Well Maintenance Water level in well measured with a sounder Hydrochloric and Sulfamic acid can be used to remove well crust. Chlorine to remove iron bacteria (new well 50 mg/l 24 hrs; old well 100-200 mg/L for shock) Well surging- physical cleaning of the well Water level in well measured with a sounder Hydrochloric and Sulfamic acid can be used to remove well crust. Chlorine to remove iron bacteria (new well 50 mg/l 24 hrs; old well 100-200 mg/L for shock) Well surging- physical cleaning of the well
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New Wells 1.Add enough chlorine to produce a concentration of 50 mg/L in the well casing. 2.Turn the pump on and off several times to mix the well (agitate). 3.Re-mix well several times at one-hour intervals. 4.Wait 24 hours. 5.Pump well water to waste until chlorine smell is gone. 6.Test for chlorine residual @ well sampling tap 7.Collect a bacteriological sample. 1.Add enough chlorine to produce a concentration of 50 mg/L in the well casing. 2.Turn the pump on and off several times to mix the well (agitate). 3.Re-mix well several times at one-hour intervals. 4.Wait 24 hours. 5.Pump well water to waste until chlorine smell is gone. 6.Test for chlorine residual @ well sampling tap 7.Collect a bacteriological sample.
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What concentration of residual chlorine should be maintained for 24 hours in a newly constructed well? 1.50 mg/L 2.50 ug/L 3.25 mg/L 4.25 ug/L 1.50 mg/L 2.50 ug/L 3.25 mg/L 4.25 ug/L
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What is the purpose of surging? 1.To clean mineral deposits from well screens. 2.To remove blockages from the distribution system. 3.To backwash filters rapidly. 4.To prepare pump motors for erratic power supplies. 1.To clean mineral deposits from well screens. 2.To remove blockages from the distribution system. 3.To backwash filters rapidly. 4.To prepare pump motors for erratic power supplies.
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Chlorine (100-200 mg/L) is an effective treatment for well screens. It helps to remove this material. 1.Slime from iron- oxidizing bacteria 2.Biofilms from ammonia-oxidizing bacteria 3.Iron and manganese oxides 4.Calcium carbonate deposits 1.Slime from iron- oxidizing bacteria 2.Biofilms from ammonia-oxidizing bacteria 3.Iron and manganese oxides 4.Calcium carbonate deposits
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Chlorine treatment of wells is sometimes referred to as ________ treatment because of the high concentrations of chlorine that is agitated (100 and 200 mg/L). 1.Shock 2.Slug 3.Attenuated 4.Chloro-biotic 1.Shock 2.Slug 3.Attenuated 4.Chloro-biotic
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Finished Well Drilled by cable tool method or rotary hydraulic Sanitary seal top of the well Surrounded by a 4-inch thick sloping slab extending at least 2 feet in all directions Typically casing extends 1 feet above 100 year flood line Grout seal well casing with concrete or clay Well screen keeps out particulates and allows water into well (properly fitted slot size) Proper sized pump Drilled by cable tool method or rotary hydraulic Sanitary seal top of the well Surrounded by a 4-inch thick sloping slab extending at least 2 feet in all directions Typically casing extends 1 feet above 100 year flood line Grout seal well casing with concrete or clay Well screen keeps out particulates and allows water into well (properly fitted slot size) Proper sized pump
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Finished Well Well screen Grout seal
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Problems: Contaminated Aquifers
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Sources of Contamination
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Problems: Overpumping/Land subsidence USGS Fact Sheet-165-00 December 2000
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This condition results when more water is removed from an aquifer than is replaced through rain and snowmelt. 1.Overdraft 2.Dry welling 3.Rising water table 4.Air binding 1.Overdraft 2.Dry welling 3.Rising water table 4.Air binding
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Problems: Overpumping/Land subsidence 20-40ft decline
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Problems: Salt Water Intrusion
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Potential problems that can affect wells are 1.Overdraft 2.Groundwater pollution 3.Salt water Intrusion 4.All of the above 1.Overdraft 2.Groundwater pollution 3.Salt water Intrusion 4.All of the above
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The objectives stated in the syllabus to learn the basics of (Parts the Hydrologic Cycle Aquifer types, Porosity/permeability, Well construction, Groundwater problems) were met ? 1.Strongly Agree 2.Agree 3.Disagree 4.Strongly Disagree 1.Strongly Agree 2.Agree 3.Disagree 4.Strongly Disagree
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