,\ q'lf-1 oo2o~ I I ,. I ·~ • I I I•" UPPER METHOW RIVER VALLEY I GROUND WATER MANAGEMENT AREA I AQUIFER TEST REPORT I I Prepared for Okanogan County Public Works I February 5, 1992 I I I I Prepared by I EMCON Northwest, Inc. 506 Royal Street West P.O. Box Drawer 8 I Kelso, Washington 98626 I Project 88902.08 I I I . r-.._, . - I . l'lloPl!JR'l'Y O.F STA.T,m O.F WAS!iJNGTON" ' - . DEPAET.ME.NT OF ECOLOGy Ll:B.R.Aay I I I I I I I I I I I I ,,. ,, I I I· Emcon J . Northwest, Inc. J . -~~ .... I . • . ' • ¢· -·~ -·. .·I' I I I CONTENTS I I TABLES AND FIGURES ................................. iv 1 INTRODUCTION . 1 I 1.1 Purpose...................................... 1 1.2 Pumping Test Background . 3 I 1.3 Relationship to Other Activities . 5 2 AQUIFER CONCEPTUAL MODEL . 7 2.1 Geology . 7 I 2.1. 1 Regional . 7 2.1.2 Methow Valley . 8 2.1.3 Mazama Bridge Area . 9 I 2.2 Ground Water Hydrology . 12 2.2.1 Recharge . 12 2.2.2 Low Flow . 13 I 2.2.3 Hydrologic Assumptions . 14 2.3 Ground and Surface Water Interactions . 15 I 3 AQUIFER TEST DESCRIPTION . 19 3.1 Department of Ecology Guidelines . 19 3.2 Test Site Description ......... ; . 19 I 3.2. 1 Pumping and Observation Well Network . 20 3.2.2 Pumping Well Design and Installation . 24 3.2.3 Deep Test Boring/Observation Well Installation . 26 I 3.2.4 Monitoring Well Construction . 28 3.3 Aquifer Test #1 . 29 I 3.3.1 Test #1 Specifications . 29 3.3.3 Test Completion . 32 3.3.4 Recommended Additional Testing . 38 I 3.4 Aquifer Test #2 . 43 3.4.1 Test #2 Specifications . 43 3.4.2 Aquifer Test #2 Completion . 45 I 3.5 Water Quality Sampling Analyses . 50 3.5.1 Sampling . 50 I 3.5.2 Analytical Results . 52 KC/METHOW·R.210fbg:11 Rev.0,02/10/92 I 589-01.08 ii I I I I CONTENTS (Continued) I 4 PUMPING TESTS INTERPRETATION . 56 4.1 General Observations . 58 I 4.1.1 Methow River Fluctuations . 58 4.1.2 Pre-pumping Conditions . 60 4.1.3 Pumping Conditions . 66 I 4.1.4 Post Pumping Water Level Conditions . 71 4.1.5 Summary . 73 I 4.2 Analytical Methods . 74 4.2.1 Theis Non-Steady State Method . 75 4.2.2 Jacob Non-Steady State Method . 81 I 4.2.3 Jacob Distance-Drawdown Method . 84 4.2.4 Hantush Partial Penetration Method . 86 4.2.5 Stallman Unear Recharge Source Method . 87 I 4.2.6 Summary . 89 4.3 Numerical Computer Model . 91 4.3.1 Model Design and Assumptions . 94 I 4.3.2 Model Runs . 99 4.3.3 Interpretations of Model Runs . 105 I 5 CONCLUSIONS AND RECOMMENDATIONS . 114 5.1 Umitations of Characterization . 114 5.2 Aquifer Characterization/Conclusions . 115 I 5.3 Recommendations . 117 I REFERENCES ..................................... 120 I I I I KC/METHOW-R.210jbg: 11 Rev. 0. 02/10/92 I 889-01.08 iii I I I I TABLES AND FIGURES I I Tables Table 3-1 - Summary of Observation Well Construction Depths ................................ 22 I Table 3-2 - Summary of Field Water Quality Measurements Pumping Test #1 ..........................37 Table 3-3 Laboratory Water Quality Data- Pumping Test #1 I Indicator Parameters ........................39 Table 3-36 - Laboratory Water Quality Data - Pumping Test #1 Total Metals ..............................40 I Table 3-3C - Laboratory Water Quality Data - Pumping Test #1 · Anion/Cation Balance ...................... .41 Table 3-4 Laboratory Water Quality Data - I Pumping Test #2 ..........................51 Table 4-1 - Mazama Pumping Tests Analyses Summary- I Transmissivity . 76 Table 4-2 - Mazama Pumping Tests Analyses Summary- Storativity I Values ................................. 77 Table 4-3 - FLOW3D Model Setup - 3-Day Pumping Test Simulation . 101 I Table 4-4 - FLOW3D Model Setup - 13-Day Pumping Test I Simulation . 103 I Figures Figure 1-1 Aquifer Test Location Map . 2 I Figure 2-1 Stratigraphic Cross-Section . 11 Figure 3-1 Pumping and Observation Well Location Map . 21 I Figure 3-2 Monitoring Network Schematic . 25 Figure 3-3 Pumping Well Construction Details . 30 I KC/METHOW·R.210/bg: 11 Rev. 0, 02/10/92 I S89-01.08 iv I I I I TABLE AND FIGURES (Continued) I Figure 4-1 Pre-Pumping Period Hydrograph of MW-9 and Methow I River ................................. 62 Figure 4-2 Pumping Period Hydrograph of MW-9 and Methow River . 68 I Figure 4-3 Pressure Reponse in MW-8 During Pumping . 69 Figure 4-4 Post-Pumping Period Hydrograph of MW-9 and Methow River . 72 I Figure 4-5 Logarithmic Plot of Time-Drawdown Data MW-8 . 79 Figure 4-6 Jacob Time-Drawdown Data Plot MW-8 . 83 Figure 4-7 Jacob Distance-Drawdown Plot . 85 I Figure 4-8 Numerical Simulation Area . 95 Figure 4-9 FLOW3D Finite Element Grid . 97 Figure 4-10 Flownet Cross-Section, Run #1 .............. 106 I Figure 4-11 Flownet Cross-Section, Run #2 .............. 107 Figure 4-12 Flownet Cross-Section, Observed . 111 I I I I I I I I KC/METHOW-R.210/bg: 11 Rev. 0, 02/10/92 I 889-01.08 v I I I I 1 INTRODUCTION I I 1.1 Purpose The purpose of this report is to document the aquifer test set up, I procedures, and findings from two aquifer pumping tests performed on a I 12-inch aquifer pumping test well in the Mazama Bridge area of the Methow I River valley (see Figure 1-1). The pumping tests were performed to determine hydrologic parameters for the upper Methow River Valley aquifer, I and, to the extent possible, to draw preliminary conclusions regarding I aquifer behavior in response to pumping stress in this area. The test design and data evaluation procedures were also established in order to I identify general relationships between the aquifer and the Methow River. I The pumping test was not designed, nor is this report intended, to provide a detailed hydrogeologic evaluation of the shallow aquifer underlying the I upper Methow River Valley. Conclusions are limited to technical aspects of I the pumping test, limitations on interpretation, and additional data needs necessary for further interpretation. I I I KC/METHOW-R.210/bg: 11 Rev. o. 02/10/92 I 589-01.08 1 I I 111246 I I I I I I I I 4ooo "'0 I g MAiAMA") / EXPLANATION I I ___ / I I -- 1 I ,... - - Approximate Boundary of Val ley AI luvium I ---~/ ,' I Perenial Stream Ephemeral Stream \ / I \ \ Elevation Contours / -4000-- \ / \ / ... ----r A ~- / I Cross-section Location I '""Vo / 1 I \ / ' I Monitoring Wei I Location Cluster \ / ---- t.m-6, 7 • I I with Well Designations - / / Sandy Note: Map modified from USGS Butte ~ I X - Mazama quadrangle. I I ~I 6000 12,000 I SCALE IN FEET I I I DATI 2/92 Rgure 1-1 DWN. MMM METHOW VALLEY GWMA Sweet-Edwards APPR •. __ EM CON IIIRVIS. __ I PROJECT NO. AQUIFER TEST LOCATION MAP 58901.08 I I I 1.2 Pumping Test Background Ecology guidelines for GWMA monitoring wells (Ecology, 1988) requires that I aquifer testing be completed for a minimum of 24 hours. Prior to initiation I of the monitoring well construction phase of the Methow Valley GWMA project, it was determined, based on a review of historic hydrologic data, I domestic supply well drillers' logs, and surficial observations of aquifer I materials that 2-inch diameter monitoring wells would not provide for adequate hydraulic aquifer testing. Ecology concurred with this conclusion. I I Although monitoring wells were to be distributed throughout the upper Methow River Valley (from Wolf Creek to above the confluence of the I Methow River and Lost River), the primary purpose of the monitoring wells I is to provide water quality data for characterization and long term I monitoring. It was intended that the hydrologic and physical characteristics of the aquifer would be determined for the intensely monitored area at I Mazama and applied, as appropriate, to the remainder of the valley. I Topographic and anticipated hydrostratigraphic conditions were expected to be the most nearly representative of the Methow Valley at this location, I and proposed development density is greatest in the area immediately I upstream from Mazama. I I KC/METHOW·R.210fbg:11 Rev. o. 02/10/92 I 589-01.08 3 I I I At Mazama, shallow and intermediate depth monitoring well pairs were constructed near the center and towards both sides of the valley, I perpendicular to the trend of the valley. Well placement was intended to I provide long term data on ground water quality below areas of potential development and surface water /ground water interaction. The six wells I were constructed using 4-inch diameter casing and screen to allow for I installation of submersible pumps that would provide for pumping capacities of up to approximately 50 gpm. It was anticipated that pumping tests I completed on each of the six wells would provide data that could be applied I to hydrologic conditions observed at the remainder of the monitoring well sites. I I During well development and preliminary aquifer testing, it was found that pumping rates approaching 50 gpm had essentially no effect on the water I levels in the pumping wells. The limited drawdown that was observed in the I pumped wells was likely due to well effects rather than aquifer effects. I Consequently, it was proposed to the County and Ecology that a high capacity well be constructed to allow aquifer tests to be conducted that I would provide the required hydrologic data.