Nye Cunty Grundwater Evaluatin Drilling Prgram Levi Kryder Nye Cunty NWRPO May 5, 2011
Outline Grundwater Evaluatin prgram Drilling prgram bjectives Brehle lcatins Data cllectin Results by gegraphic lcatin Future wrk
Grundwater Evaluatin Prgram Funding prvided by DOE fr characterizatin f water resurces in suthern Nye Cunty Grant number DE-FG52-2006NA27205 Original award f $2,477,000 in April 2006 Remaining $1,511,000 transferred t NWRPO in April 2010 Wrk accmplished under riginal grant: Gephysical studies and determinatin f sil characteristics near Ash Meadws (BYU) Established Nye Cunty Water District Cnstructin f grundwater flw mdel fr Pahrump Valley (DRI) Wrk elements develped fr remaining funding: Drilling Prgram (cmpleted) Evaptranspiratin study (USGS) Suthern Amargsa embedded Mdel (USGS) Outreach and resurce management
Drilling Prgram Objectives In general, the bjectives were t infill data gaps in the water level measurement prgram, better understand gelgic cntrls n grund water flw, and determine aquifer characteristics Specific bjectives: Pahrump Valley infill data gaps in WLMP, especially n the Pahrump Fan Amargsa Desert determine head relatinships near the Gravity Fault, cllect baseline flw and chemical data Oasis Valley cllect baseline flw and chemical data in areas (far) dwn gradient frm previus nuclear tests Prvide data t assist Nye Cunty Water District with basic water resurce characterizatin in suthern Nye Cunty
Brehle Lcatins Lcatin Number f Wells Pahrump Valley 5 Amargsa Desert 7 Oasis Valley 2 Hydr Resurces, Inc. 14 brehles - 4,600 feet ttal drilled Tw phases f drilling: Phase I May 2010 t June 2010 Phase II Nvember 2010 t January 2011
Drilling and Brehle Data Cllectin All data cllected under NWRPO Quality Assurance Prgram Drilling All brehles lcated n private lands r existing EWDP sites Air fam, cnventinal circulatin 10-inch surface casing set t 20 feet, 8-inch brehle drilled t ttal depth Brehles drilled t apprximately 100 feet belw water table Shallwest brehle was OV-2 (119.8 feet), deepest was PV-1 (610 feet) Brehle data cllectin Cuttings samples cllected every 5 feet Sediments lgged using USCS descriptins Cnslidated rck lgged using quantitative descriptins Brehle gephysical lgs Open-hle (gamma, resistivity, temperature, caliper) Cmpletin (gamma, temperature, fluid resistivity, density)z
Well Cmpletin Mnitr well cmpletin Wells cmpleted with 4- inch Schedule 80 PVC Original plan was t cmplete with 4.5-inch PVC, allwing use f higher capacity 4-inch pump during pump testing Sandpack and grut emplaced using tremmie methds Surface cmpletin with prtective steel casing, cncrete pad, and lcking well cap
Pump Testing and Water Sampling Wrk being cnducted nw Pump tests 4-inch casing limited us t use f 3-inch pumps (lw flw rates and very little aquifer stress) Step testing Cnstant discharge testing Water chemistry Wrking with DRI (Ren), DRI (Las Vegas), BYU, and ther independent labs t analyze water samples fr the fllwing: Majr anins and catins Metals Selected istpes Tritium Strntium Nble gases
Pahrump Water Table Elevatin n GWE wells
Pahrump Water Table Elevatin with GWE wells
Results Pahrump Valley Infill data gaps in water level wells GWE wells and WLMP wells help t refine water level cnturs within Pahrump Valley Pump testing cnducted in GWE wells prvides additinal aquifer infrmatin that is lacking in data gap areas Water chemistry data will expand n existing reginal data set
Amargsa Area Wells and Springs
Amargsa Water Table Elevatin n GWE wells
Amargsa Water Table Elevatin with GWE wells
Results Amargsa Desert Gravity Fault Thicker sequences n the west side (hanging wall) f the fault, presumably due t accumulatin f sediments in dwn-drpped basins Thinner stratigraphic sequences n the east side Water table elevatin n the east side f the Gravity Fault (GF-4) is 74 feet higher than n the west side (GF-3PA) Similar relatinships seen in USGS wells t the suth where water table elevatin at GF-2A n the east side f the Gravity Fault is 87 feet higher than GF-1 lcated west f the fault Cmpartmentalized stratigraphy At GF-4 water prductin at 110 feet in carse-grained permeable sediments was 75 gpm and at GF-4PA at same depth in less permeable clayey sediments prductin was 25 gpm Pssibly graben-like features bunded by high angle structures act as barriers between sedimentary units with cntrasting permeabilities At GF-4 the sediments cntain 200 feet f carse-grained gravel and sand that is absent 60 feet t the west at GF-4PA Cautin shuld be taken when generalizing hydrgelgic prperties alng the trace f the Gravity Fault! Need mre wells t the nrth alng the Gravity Fault Water table elevatin cntur refinement
Results Oasis Valley Artesian cnditins at OV-1 OV-1 is a flwing artesian well with a head apprximately 2 ft abve grund surface Lcated in Oasis Valley spring discharge area Prblems with OV-1 cmpletin Artesian pressure cmprmised the integrity f grut seal Effrts t cntain leak were unsuccessful Current plan is t plug back and abandn OV-2 is a viable well situated within prminent discharge area within Amargsa River channel
Future Wrk Gephysical survey (TEM, CSAMT, resistivity) transects acrss the Gravity Fault Additinal wells straddling the Gravity Fault t examine head relatinships Incrprate gelgic and hydrlgic data int SAMM framewrk as apprpriate Examine cnnectin between surface water infiltratin and grundwater
Acknwledgements Drilling and sampling crew frm Nye Cunty and Hydr Resurces Jhn Klenke, Bb Wilcxn, and Jamie Walker Nye Cunty management Department f Energy and Bruce Stlte fr cntinued supprt Tm Buq fr starting the whle GWE grant prgram
Questins?