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Mining and the Environment
Published in Mritunjoy Sengupta, Environmental Impacts of Mining, 2021
Impacts from groundwater drawdown may include reduction or elimination of surface water flows; degradation of surface water quality and beneficial uses; degradation of habitat (not only riparian zones, springs and other wetland habitats, but also upland habitats such as greasewood as groundwater levels decline below the deep root zone); reduced or eliminated production in domestic supply wells; water quality/quantity problems associated with discharge of the pumped groundwater back into surface waters downstream from the dewatered area. The impacts could last for many decades. While dewatering is occurring, discharge of the pumped water, after appropriate treatment, can often be used to mitigate adverse effects on surface waters. However, when dewatering ceases, the cones of depression may take many decades to recharge and may continue to reduce surface flows. Mitigation measures that rely on the use of pumped water to create wetlands may only last as long as dewatering occurs.
Potable Water Source
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
After a well is developed, conducting a pump test determines if it can supply the required amount of water. The well is generally pumped for at least 6 h (many states require a 48-h yield and drawdown test) at a rate equal to or greater than the desired yield. Yield is the volume or quantity of water per unit of time discharged from a well (GPM, cubic feet/sec). Regulations usually require that a well produces a minimum of 0.5 gallons per minute per residential connection. Drawdown is the difference between the static water level (level of the water in the well when it has not been used for some time and has stabilized) and the pumping water level in a well. Drawdown is measured by using an airline and pressure gauge to monitor the water level during the 48 h of pumping.
Injection of Produced Wastewater
Published in Frank R. Spellman, Hydraulic Fracturing Wastewater, 2017
After a well is developed, conducting a pump test determines if it can supply the required amount of water. The well is generally pumped for at least 6 hours (many states require a 48-hour yield and drawdown test) at a rate equal to or greater than the desired yield. Yield is the volume or quantity of water discharged from a well per unit of time (e.g., gpm, ft3/sec). Regulations usually require that a well produce a minimum of 0.5 gpm per residential connection. Drawdown is the difference between the static water level (level of the water in the well when it has not been used for some time and has stabilized) and the pumping water level in a well. Drawdown is measured by using an air line and pressure gauge to monitor the water level during the 48 hours of pumping.
Assessment indices of littoral habitat condition for lakes in Maine and New England, United States
Published in Lake and Reservoir Management, 2023
Jeremy Deeds, Aria Amirbahman, Kirsten Hugger, Philip R. Kaufmann, Leslie J. Matthews, Kellie Merrell, Stephen A. Norton
Managed fluctuations of lake water levels occur in some New England lakes, usually for macrophyte control, flood control, or power generation (Cooke et al. 2005, Mjelde et al. 2013). Water level drawdowns can have adverse effects on littoral habitat, especially when coupled with shoreland development (Evtimova and Donohue 2016, Carmignani and Roy 2021). We did not specifically address the effect of water level fluctuations in these littoral habitat condition assessment models, but poor littoral habitat scores in some lakes with otherwise minimally developed shorelands, such as Chittenden Reservoir and Green River Reservoir in Vermont (Figure S1) and Upper Mary Jo, Tunk, and Wood in Maine (Figure 3), may be explained by water level fluctuations, whether lake levels are actively managed or the lake has a natural outlet and is especially susceptible to drought conditions. Linkages among water level fluctuations, shoreland development, and littoral habitat condition should continue to be investigated in future studies. Advances in satellite imagery analyses (e.g., Li et al. 2019) may help to quantify seasonal littoral zone exposure due to water level changes, which in turn would help to disentangle the effects of water level fluctuations and shoreland development as confounding factors influencing littoral habitat condition.
Postmortem analysis of safe-yield estimation of a heterogeneous aquifer for rural water supply
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2022
Elizabeth A. Munroe, Masaki Hayashi, Laurence R. Bentley
Methods based on pumping tests, like the Q20 method, are useful for estimating storage depletion in an aquifer, but storage depletion is only one of many factors that need to be considered in the assessment of sustainable groundwater extraction rates (Alley and Leake 2004; Pierce et al. 2013). A drawdown of 20 m in a confined aquifer will have undesirable effects even if the water level is higher than the top of the aquifer. For example, there may be other wells screened in the same aquifer but equipped with a pump with a smaller lift capacity than the tested well. The pump in such a well may need to be replaced, at a sizable cost to the well owner. The large drawdown in the confined aquifer may induce drawdown in a shallower, unconfined aquifer by the leakage through the aquitard separating the two aquifers. The induced drawdown in the shallow aquifer may cause the water table to drop, which can have negative environmental consequences such as a reduction in discharge from springs fed by the aquifer or in baseflow of streams connected to the aquifer. Therefore, it is recommended that pumping-test-based estimates of storage depletion, such as the Q20 method, be used as one component of adaptive aquifer management, in which the aquifer water level is monitored and the extraction rate is adjusted as part of the requirement for the renewal of a water extraction licence.
Aquifer potential of the transboundary crystalline-sedimentary complexes: from Northcentral Nigeria to Northwestern Cameroon border
Published in Water Science, 2021
Prior to each pumping survey, the saturated zone was screened to about 90% in order to achieve full penetration of the aquifer thickness. According to Kruseman and de Ridder (1994), screening across the saturated part ensures maximum discharge from horizontal flow – a criterion that meets the basic assumption of flow to pumping wells. Flow rates were manually determined with respect to specifications of EPA (1995) by observing the time required to pump-fill a calibrated bucket of a known volume, after the Wells were surged for about one minute (see ESM No.33ii–iv). The constant rate method from single well approach was used in two phases, namely, (1) the pumping phase vis-a-vis submersible pump apparatus (1.5 HP) to generate data for drawdown (h – h0) and (2) recovery phase to produce data for residual drawdown (h – h0)′ via spontaneous recharge. In order to produce reliable constant discharge, each pump was powered by a portable generator. Two parameters were monitored, namely, time (using stopwatch) and water levels in the wells using a dip meter. The drawdown was recorded on aquifer test data sheet (see ESM No 33{b-k}) as the difference between transient water levels during pumping (h) and the static water level (h0). The pumping test period lasted until pseudo-steady (or, equilibrium) state was attained; when the water levels in the well stabilized. The pump was turned off (ie shut down) and the recovery phase commenced immediately. The recovery water levels were timely observed and recorded and the residual drawdown evaluated with reference to the (h0) until the water level stabilized almost at the initial pre-pumping static water level (h0).