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HomeMy WebLinkAboutVILLAGES VIEW ESTATES WEST Aquifier Test and Data EvaluationF TERRASAT, INC. 1413 West 31st Avenue, Anchorage, AK 99503 (9=344-9370Geological Consulting Environmental Restoration Aquifer Test and Data Evaluation for the proposed Villages View Estates West Prepared for: Kin Shaw and Son Shaw P. O. Box 110637 Anchorage, AK 99511 By: TERRA SAT INC. 1413 {fest 31"Avenue Anchorage, AK 99503 December 20, 2001 TABLE OF CONTENTS rINTRODUCTION.........................................................................................1 SiteDescription.............................................................................................................. 1 SITE CONDITIONS.....................................................................................1 7 PROFESSIONAL SIGNATURES...............................................................5 -- STEPTEST :. Figure I Site Location Map ....................................................................................................1 Water Well Locations Figure 3 AQUIFERTESTS.........................................................................................2 L Figure 4 Log -log plot of time vs. drawdown at Lot 2 Figure 5 Semi -log plot of t/t' vs. residual drawdown at Lot 2 j Figure 6 DATA INTERPRETATION........................................................................2 Figure 7 Semi -log plot of time after pumping vs. calculated recovery at Lot 2 Transmissivitj................................................................................................................. 2 Figure 9 F Static Water Elevations in Drinking Water Wells Storativit}........................................................................................................................ 2 Specific Capacity and Long -Terni Yields...................................................................... 3 '-' GIS EVALUATION......................................................................................3 COMPUTER MODELING..........................................................................3 r CONCLUSIONS............................................................................................4 Local Aquifers and 11'ell Yields..................................................................................... 4 Ea7)ected Yields.............................................................................................................. 4 Potential Impacts to Surrounding Users....................................................................... 4 RECOMMENDATIONS..............................................................................5 7 PROFESSIONAL SIGNATURES...............................................................5 -- FIGURES :. Figure I Site Location Map Figure 2 Water Well Locations Figure 3 Semi -log plot of t/t' vs. residual drawdown at Lot 3 L Figure 4 Log -log plot of time vs. drawdown at Lot 2 Figure 5 Semi -log plot of t/t' vs. residual drawdown at Lot 2 j Figure 6 Semi -log plot of time vs. drawdown at Lot 2 Figure 7 Semi -log plot of time after pumping vs. calculated recovery at Lot 2 Figure 8 Calculations of Specific Capacity (Theoretical) for a pumping well Figure 9 F Static Water Elevations in Drinking Water Wells APPENDICES Appendix A Well Logs Appendix B Aquifer Test Data r r INTRODUCTION Kin Shaw and Son Shaw contracted TERRASAT, INC., to conduct an aquifer test in the Proposed Villages View Estates Nest Subdivision, Anchorage, Alaska. Our objectives for this project are to evaluate the aquifer test results to determine the long-term capacity of the aquifer and the nature of the aquifer and determine the potential impacts to water wells in the surrounding area. Our scope of services includes: • Conducting a short-term aquifer test to estimate an appropriate discharge rate for the long-term test. • Conducting a long-term test aquifer test to evaluate the production capabilities of wells in the proposed subdivision. • Determining the likelihood that the proposed subdivision will impact the surrounding well users. I Site Description The Proposed Villages View Estates Nest Subdivision is located east of the Villages Scenic j' Parkway, south of Potter Valley Road in Anchorage, Alaska (Figure 1). The sectional description for the area is the SW 1/4 Section 14, Township 11 North, Range 3 West, Seward Meridian. ` SITE CONDITIONS M -W Drilling, Inc., completed wells on Lots 2, 3, & 4 in the proposed subdivisio on October 19, 2001 (Figure 2). Each well is constructed with 6" steel casing, whi t is grouted approximately 20 feet into bedrock. The wells are completed open -hole ' bedrock and r intercept water from fractures in the bedrock. [The well on Lot 2 is 368 feet ep, with casing extending to approximately 41 feet below ground surface, based on the veil construction diagram (Appendix A)" The static water level is approximately I foot abov casing. This well is located approximately 80 feet north of the well on Lot 3. The well on Lot 3 is 367 feet deep, with casing extending approximately 29 feet below ground surface, based on the well construction diagram (Appendix A). i The static water level is approximately 1 foot below the (' [" top of casing. The well on Lot 4 is 468 feet deep, with casing extending approximately 44 feet { below ground surface, based on the well construction diagram (Appendix A). The static water level is approximately 24 feet below the top of casing. This well is located approximately 327 feet south of the well on Lot 3. STEP TEST TERRASAT, INC., installed water level monitoring equipment in each well on October 30, 2001. M -W Drilling, Inc., installed a pump at Lot 3 and conducted a step -drawdown test on October 30, 2001. The available drawdown above the top of the pump was 299 feet. We 1 , pumped for four 22 -minute intervals, with increasing discharge rates of 1.2, 1.7, 3.7, and 4.0 gpm, with a total drawdown of approximately 100 feet. This well recovered at a rate of 2 gpm immediately following the step test. Results of the step test suggested that a pumping rate of 3 :. gpm should result in 70% to 90% drawdown in the production well at the end of the 24-hour test period. i P:\20110B - VillVicw Aquifer Test\12-20-01 V View Aq test report.doc Page I of 5 t^ AQUIFER TESTS I^ Aquifer drawdown and recovery tests were conducted at the well on Lot 3 from November 2 to November 5, 2001 following recovery from the step test. The well was pumped at a nearly continuous rate of 2.3 gpm for 22 hours. The production well (Lot 3) and two observation wells (Lot 2 and Lot 4) were monitored during the test. Results from the test are presented in Appendix B. Total drawdown in the production well at the end of the 22 hours was 205 feet. Drawdown at Lot 2 was 25 feet. We detected no drawdown due to pumping in the well on Lot 4. The water level fluctuations observed in this well resulted from lunar cycles and changes in barometric pressure. iWe conducted an additional short-term aquifer test in the well at Lot 4 on November 7, 2001 to estimate the production capacity. The pump was set in approximately 276 feet of water and run for 136 minutes at a discharge rate of 4 gpm until total (100%) drawdown was achieved. This well recovered at a rate of 1.5 gpm for the first 20 minutes of well recovery. DATA INTERPRETATION TERRASAT INC., evaluated the aquifer test results to determine the long-term capacity of the aquifer and the nature of the aquifer. The availability of water depends on the transmissivity of the aquifer (or aquifers), storativity, and recharge. The data from the aquifer test most closely match a model that was developed for bedrock aquifers by Moench. This model is for a fractured bedrock aquifer where high -porosity fractures are drained first and the low -porosity bedrock media is drained second. Our evaluation focused more closely on the late -time drawdown data to see how the aquifer responds to long-term pumping. The late -time data from the aquifer test closely match the model developed by Theis. This model is for a confined artesian aquifer, where wells have no storage, and storage in the confining layers (aquitards) is negligible. The close match of the data suggests that this rock aquifer responds like an unconsolidated aquifer during extended periods of discharge. The Theis model, therefore, provides a reasonable approximation to predict the transmissivity, storativity, and long-term capacity of the aquifer. rTransmissivity Transmissivity is the rate at which water can move through an aquifer of known saturated thickness. Extrapolation of the transmissivity data allows us to estimate the maximum now rate of the well. Transmissivity values calculated using recovery data from a production well usually give rough approximations for the aquifer immediately surrounding the well. Transmissivity calculated from the recovery data is approximately 2.8 gallons per day per foot (gpd/ft) (Figure 3). Transmissivity values calculated from observation well data give the best approximation for the area between the production and observation well. Transmissivity j" values calculated using data from Lot 2 range from about 2.9 to 18 gpd/ft (Figures 4 - 7). 1. Storativity Storativity is a ratio of the volume of water released by gravity drainage to the volume of I saturated media from which the water drains. Storativity values calculated from observation well data give the best approximation for the area between the production and observation well. In the case of bedrock, two storativity values can be estimated. The first value is based on early -time data. This storativity provides a reasonable estimate of the storativity of the rock r fractures. The second storativity value is estimated from late -time data and represents the P:\20110B - VillView Aquifer Test\12-20-01 V View Aq test report.doc Page 2 of 5 storativity of the rock. This value is more representative of the aquifer as a whole when estimating long-term production. Storativity values calculated using data from Lot 2 range .. from about 0.000037 to 0.0016 (Figures 4, 6, & 7). Published literature suggests that these values are within the expected range for a fractured bedrock aquifer. •- Specific Capacity and Long -Teri yields We selected representative transmissivity and storativity values to estimate the specific yield and maximum sustainable pumping rates for long-term pumping from each well. A j transmissivity of 8 gpd/ft was selected as an estimate of the aquifer capability. A storativity of 0.0001 was selected as an estimate from the aquifer test analyses. Specific capacities and discharge rates for continuous pumping of the well for 1/2, 1, 10, and 20 years are shown in (^ Figure 8. Results indicate that each well should be able to support a pumping rate of 1.0 gpm l for ten years of continuous pumping. GIS Evaluation We used a Geographical Information System (GIS) to determine if wells in close proximity j' have similar static ground water elevations. This is important because wells grouped l , according to static water elevations generally have good hydraulic connection. This evaluation allows us to identify different aquifers and determine if it is likely that additional wells would I^I impact existing wells. 1. . Me static water levels plotted in Figure 9 show general north -south trends. These trends suggest that the fracture systems intercepted by water wells have strong north -south components. This supports findings in our earlier report where photo interpretation results showed a possible north -south trending fault near the proposed subdivision. The presence of .- strong north -south trends in the water level data suggest that the aquifers may show little or no hydraulic connection in an east -west manner. Computer Modeling TERRASAT, INC. conducted computer modeling to estimate how the aquifer will respond to long-term pumping. Results of the computer simulation suggest that the Theis model gives a reasonable approximation for the expected drawdown in an observation well for a simulation of long-term pumping. We ran a simulation of the wells on Lots 2 and 3 with a constant discharge rate of 1 gpm to estimate the well interference. Our simulation results suggest that l the interference and additional drawdown at these wells should not cause the water elevation to exceed the available drawdown for tip to two years of continuous pumping. This estimate is very conservative, as it does not consider recovery that would occur between pumping cycles. Intermittent pumping allows the wells to recharge, thus allowing the user to remove more water from the well. TERRASAT, INC. conducted computer modeling to estimate the potential impacts to surrounding well users. We made a worst-case assumption by simulating a single east -west ^, fracture system that spans the distance of two subdivisions. ;Our simulation considered four (wells in the same fracture system (three in the proposed subdivision and one in the nearest subdivision), with each'pumping continuously at 0.5 gpm for one year. The simulation results suggest that a well in the same fracture system, located 500 feet from three wells in the proposed subdivision, could experience up to 50 feet of water level decline due to well r j P:\20110B - Villview Aquifer Test%12-20-01 V View Aq test report.doc Page 3 of 5 F ` interference. This situation is very unlikely to be representative of actual site conditions based on the evaluation of available water level data from existing wells (Figure 9). A wide range of r ground water elevations suggests that many different fracture systems, with varying amounts of pressure head, exist in the area. This interpretation is further supported by the long-term aquifer test in which no apparent connection was observed between the wells on Lots 3 and 4, which are less than 350 feet apart. Thus, there is alvery low probabilitythat wells in the proposed subdivision will impact the surrounding well users. Conclusions Local Aquifers and Well Yields Past ground water studies conducted by TERRASAT, INC, on the hillside in Anchorage, suggested that most wells in bedrock aquifers near Potter Valley typically produce less than 0.5 •- gpm. This production rate is generally considered marginally adequate for single-family homes, based on the Municipality determination that a well provides adequate water if it produces 150 gallons per day per bedroom (0.10 gpm). Based on tests performed at the (" proposed Villages View Estates West subdivision, a sustained rate of 1.0 gpm appears likely, ` . thus meeting this criteria. Furthermore, the wells in the proposed subdivision appear to be capable of long-term production at 1.0 gpm and should be considered adequate for homes with (' up to nine bedrooms. E.epected Yields The aquifers (fracture systems) exploited by wells in the proposed Villages View Estates West subdivision, have high head pressures (high static water levels). This suggests that the water recharging the fractures likely comes from high -elevation areas in the Chugach Mountains. Both the short and long aquifer tests conducted at these wells suggest that the fractures from which the water is extracted and the rate at which the water can be pumped are small. This means that these aquifers may experience long-term water level decline if the pumping rate j� exceeds recharge. Computer modeling supports this conclusion, which shows the potential for l . significant water level decline after only a few years of pumping. This is consistent with what r we would expect in a rock aquifer with a low density of water -bearing fractures. ` The aquifer test evaluation and computer modeling we conducted are conservative models that overestimate drawdown and long-term water level decline. Thus, a factor of safety is incorporated into each analysis. Aquifer tests and computer modeling conducted for the proposed subdivision show that long-term pumping at rates of approximately 1.0 gpm should not cause well interference beyond available head. This means that a well on each lot in the proposed Villages View Estates West subdivision should be adequate for a home with up to nine bedrooms. ^, Potential Itupacts to Sttrrotutding Users Interpretation of the aquifer tests performed and available static water level data for nearby water wells suggest that a connection between rock fracture aquifer systems in the proposed Villages View Estates West subdivision and those in The Villages subdivision is very unlikely. This is further supported by the apparent north -south trend in local fracture systems as interpreted from aerial photographs. This means that the hydraulic connection in an east -west manner is likely very small and that little to no impact is expected at wells in The Villages r subdivision. P:\201 IOB - VillView Aquifer Test\12-20-01 V View Aq test report.doc Page 4 of 5 ^ I The aquifer tests conducted were limited to monitoring impacts to the wells in the proposed j^ subdivision. Thus, no data exists to determine if the water wells in the proposed subdivision are hydraulically connected to those in the adjacent subdivision. Computer modeling of a very unlikely and worst case situation, suggests that if the wells were in the same group of rock fractures (same aquifer), the wells could experience up to 50 feet of water level decline after one year. The information provided from aerial photography, water levels, and aquifer tests, however, suggests that this simulation does not likely representative of actual site conditions. 1 Recommendations The proposed wells appear to meet MOA required flow criteria. If higher flow rates are desired, however, a water -well development method, known as hydro -fracturing, may be applicable. This method uses pressurized water and pea gravel to propagate and hold open the existing fractures. Well yields increase as additional water -bearing fractures are intercepted, making more water available to the well. This method effectively increases the aquifer size, which can improve the well yield while decreasing the amount of long-term water level decline. TERRASAT, INC. recommends using this method on a case-by-case situation to achieve high volumes. I Aquifer tests and computer modeling show that the wells in the proposed subdivision are adequate to support houses with up to nine bedrooms, based on the Municipality standard of ,.. 150 gallons per day per bedroom. To avoid excessive amounts of drawdown during high -use times (morning & evening), we recommend using well storage tanks to minimize the length of pumping cycles and maximize the time for recharge between pumping cycles. This will allow more time for the aquifer to recover, which may delay long-term water level decline and preserve the aquifer. j� The data presented in this report should be considered representative of the time of our site I . observations. Changes in the conditions of the property can occur with the passage of time. The findings we have presented within this report are based on limited test data; they should not be construed as a definite conclusion about aquifer characteristics at the site. In the event t , that future studies encounter subsurface conditions that appear different from those we encountered, we should be advised so we can review those conditions and reconsider our interpretations. I^ Please contact us at 344-9370 if you have any questions. Professional Signatures Bill Lai rence Dan Young —J( Senior Flydrogeologist Certified Professional Geologist rGround Water Professional P:\201 IOB - VillView Aquifer Test\12-20-01 V View Aq test rcport.doc Page 5 of 5 Gni w r i ' t I I. 4 F O O O _, M M ..I -.li- I I M M ..I — N 7-10 i I 0 I I i i i � i O O 4=kn O 00 N (1J) s'UMOpekeap jenp!salj O W) N M G:. r r tic 0 0 0 0 00 N '^ 00 o - -- � .� •s F I a� o o � 0 r. C� i � M V I cd ti �. N II w ovo C _ N o0 v rn .cN� +-� o O M M 00 o ozaeq b M M � N 00 0' 4 2 II o Orq00 en O (1j) S lumop w(j tic '^ o - -- � .� •s F I a� o i � M I ti �. N II w ovo _ N o0 rn o M M 00 � b M M � N 00 0' 4 2 II o tic I F N O �4 os O 03 O O 0 0 7- O O �o w O p N O N O O N O M (13) s'UMPAWIG n r PM" r 0 0 0 0 0 (1J) ,s-s'.(Ja.waoJ palelnaja:) 70 L CL V. 03 U r-+ C� U v� � o ,moo e^ •� N •E +� O w � � � a C h ^� W C ct W E O U °J O O Cll bI O — I 0 0 0 0 0 (1J) ,s-s'.(Ja.waoJ palelnaja:) 70 L CL V. M I i i — I N .. I\ o00 O 0 Q\ 00-- y --------- -- - 00 - a o F i H II 0 0 0 0 0 (1J) ,s-s'.(Ja.waoJ palelnaja:) 70 L CL V. l 11 Calculations of Specific Capacity (Theoretical) for a pumping well Q/s Specific Capacity (gpm/ft) 1 hour= 0.007 gpm/ft Q/s= T/(264log(Tt/2693r2S}66.1) 1/2 year 0.004 gpm/ft 1 year= 0.004 gpm/ft 10 year = 0.003 gpm/ft 20 year = 0.003 gpm/ft Q discharge (gpm) = 2.3 s drawdown (feet) available above pump = 298 T coefficient of transmissivity (gpd/ft) = 8 S coefficient of storativity (dimensionless) = 1.00E-04 r„, nominal radius of well (ft) = 0.25 t time after pumping started (min) = 1 hour = 60 = 1/2 year = 262800 1 year = 525600 10 year = 5256000 20 year = 10512000 Recommended maximum sustainable pumping rates 1/2 year = 1.1 gpm 1 year = 1.1 gpm 10 year = 1.0 gpm 20 year = 0.9 gpm Hantush 1960 estimation Figure 8 r r F C CD! c c Oiu c Zu.u. U. U. 5 as N 1a 0 Q$ C z (/) In O IN O IA G IA G G� CRtulto%0 w N N A 0. F- .c,,:•••DOD 12 �" ` i i '� _ �' f 5 _ �.. _I .. ., '• �- i � i .. � � 1 I ' �.' f I 1 1 � 1 ., I ��.� �� 1 .� ' �.� �` .. � M� I:.. I 1. i i a � _ i .� 1 1 � 1 j 1 _ ; _ i r 1 ? i _ � i _ ` i ! � 1 . i .: I i 1 � � I �i i APPENDIX A F Well Logs F F. F F r Job No.: 01-202 Permit No.: SWO10402 Project No.: N/A M -W Drilling, Inc. �" • P.O. Box 110378 • Anchorage, AK 99511 • ` •907-345-4000 t• 907-345-3287 Fox• I. F I. . F r A F I , F o Well Owner. Groundwater Well As -Built dt Log Shaw, Kin *Use of well: Dom mic nt 2. Vil6vot Vieux Suhdivi.inn Tract IR Construction #mokDepth: 368' ♦CeslnjSlu: 6" ♦Cased To. 43.8' •Magri!/: A53Steol oDrWMethod: AlrRotary Peef. o Wdl Cowepletion- Open end X Screen Peefomfed _ Merhod: ♦ ScreeW Perforsdow descrodon: ♦ Grorl Notes: Whole drilled to 44', 6" casing run to 43.8' and anuhis tremie ground with neat cement to surface. o wea Derelopn►enC Method. Air surge Notes: •Stalk warn level (SWI) +1 (above) (Iedow) top of eating (700. o WeH yield rest at 2 jallona pee mtnale (GPMj/ ) fvr 2 hours Wilk I DO% of drawdown (DD) fYom stalk tern (SWI). ♦Method: Air lift • Dole of enmpletlon. 16 October 2001 • Pump listau. ..r_n r -- Depth In ket from top of casing, Detatts of formations netmted sbe of material color and hardness. 0 TO 3 Casing sticku 3 TO 5 Clay: brown silty 5 15 TO TO 15 -.24 Bouldergavel: brown, very sil /claYey Bedrock: broken/weathered brown clay mixed in 24 TO 193 Bedrock: siltstone/ claystone argillite, blue -black, competent/ hard, TO no detectable water 193 TO 199 As above: reddish streak very small water sea 199 TO 368 Bedrock,_as above: blue -black, small water seaps in sporadic fractures �___. TO TO TO _. _ TO TO — --- -- TO TO ' _.._--..._. _.._ M No.: 01-202 Permit No.: SW810401 r" Project No: N/A M -W Drilling, Inc. r*P.O. Rax 110378#Anchorcge, AK 995114 •907.345-4000 9 907-345-3287 Fox• (" -Groundwater-Well As -Built do Low l ♦ Weft owner.Shaw, Kin ♦ Use of Item Domestic •LgalDacdp&n: Lot 3. Villaces View Subdivisiam!' act 18 Anchorage, Alaska r !r!— I. F F. F cons etion • Hole Depth. 367' • Carbo Size: 6" • Cared To: 31.8' *Materhd: A 53 Steel • DrlU Method: Air Rotary Perf. ♦ WeU Comp/dion- Open end X Screen Perforated Method: •SMew/Perfonadon deaerfptfon: None • Crow Nota: 10" bole drilled to 31', 6" casing run and annulus was tremle grouted with neat cement to surface. ♦ WeU Development: Method: Air surge N/etes: • Smtk waterkvd (SWL) 7' (obaw) (below) top of earths (TOC). o Wdl ylebt tat at 2-3 saUons per mbwte (GPM)I) for 1 hon" wkh 100% of drawdown (DD) front ste de kvd (SWI). •Merhod. Airlift • Date of eonrple0on: 19 October 2001 • Pump !ASIS!.• Wall I . Depth In feet from top of eating. Details of formations penetrated, size of malerlal color and hardness. 0 TO 2 Casing stickup 2 TO 8 Boulder ravel: brown undifferentiated, very silty/clayey, cobbley 8 TO 12 Bedrock: blue siltstone/ claystone argillite, fractured/weathered, TO loose and broken. 12 TO 43 As above: blue -black hard competent 43 TO 48 As above: reddish 48 TO 302 As above: blue -black, few small water seas less than 1 gpm 302 TO 347 As above: fractures with small water sea s 347 TO 367 As above: fewer fractures, slight increase in water TO TO TO TO or TO TO r, lU/ LJ/ LOOT 1:1. bl a"JJGOI Pi W N A""l',u, A. . . , MUM of formation netrated, wise of materiol, color and hardness. Job No.: 01-202 TO 3 Permit No.: SWO10400 3 TO Project No.- N/A Fill_ M -W Drilling, Inc. TO 10 i P.O. Box 110378 * Anchoragc, AK 99511 • 10 TO •907-345-4000 • 907-345-3287 Fox• Fractured rock and clay: brown 23 TO 43 Bedrock: siltstone/ claystone argillite weathered and fractured, with Groundwater Well As -Built & Lor TO • Well Owner: Show, Ken ♦ fist of WeL; Domestic 43 •Lesal Description: Lot N4, Villetec View Estates. Tinct IB 388 Bedrock: as above, blue -black, small water seas in fractures at 185' Anchorage, Alaska TO Congtrut:tion 388 TO _ 468 _ As above: slip t water increase, no detectable fractures •Hole Depth: 468' 4CatlasShe: 6" ♦Cased To: 43.1' *Material: A33Steel r *"IMe0od: Alt Rotary TO ,.. Perf. TO • Well Complaton- Open end X Screen per Mer/rod: __ •screa✓Pegbratlon dereronon: None • Grour Nora: 10- hole drilled to 471,6" Cuing nm and grouted with neat cement. Pumped TO through Cling to surface. _ NWWA—CertWed-Cantricivr -- r•, F F r ♦ Wei) Development: Makod: Air aurge Notes: •static waterlevel (sWb) (atiaw) (AdowJ wp sjeas/nt (TOCJ. • Well ykld test at I ' PaBons per minwte (CPM)/ ) jar 1 hours with I OW, of drawdown (DD) front Us* level (SWL). *Method: Airlift • hate of cnngdetlon: I 1 October 2001 • Put p lnstallt Wall I ft" Depth to feet from top of caskar, MUM of formation netrated, wise of materiol, color and hardness. 0 TO 3 Casing stickup 3 TO 6 Fill_ 6 TO 10 Boulder vel: brown, very sit 10 TO 23 Fractured rock and clay: brown 23 TO 43 Bedrock: siltstone/ claystone argillite weathered and fractured, with TO white -blue clay 43 TO 388 Bedrock: as above, blue -black, small water seas in fractures at 185' TO and 350' 388 TO _ 468 _ As above: slip t water increase, no detectable fractures TO TO ,.. TO ' TO TO _ NWWA—CertWed-Cantricivr -- i I, APPENDIX B I r Aquifer Test Data i r F FAquifer Test Data • Lot 2, Villages View Estates West S'D t^ 1 I LoT2 241aR mon.xls 12120/01 1 oft Source File: P'.\201100-MQUIFE-1\2 2411R.DAT Location: Lot 2 - Monitoring Well Sun: 112/01 10:00:44 End: 1115•'0 111:37:43 • Date Minutes Feet of Water Drawdown I11L01 10:00 0 34.41 0.00 Stan Water Level Monitoring I12'0110:02 2 34.42 .0.01 t• 112'0110:04 4 34.49 -0.08 112'0110:06 6 34.53 .0.12 112.0110:08 8 34.55 .0.14 112'0110:10 10 34.56 -0.16 r 112'0110:12 112'01 10:14 12 14 34,55 34.54 0* 14 -0.I3 Stan Pump in Prwfuction Well Il 112'0110:16 16 34.52 -0.11 112'0110:18 IS 34.50 .0.09 11/2!0110:20 20 34,47 -0.06 r.. 112VI 10:22 22 34.45 .0.04 112.01 10:24 24 34.42 .0.01 Timc(min) Monitoring well begins feeling effects of pumping 112.0110:25 25 34.40 0.01 1 • 112'0110:26 26 34.39 0.02 2 1120110:27 27 34.38 0.03 3 n 112'0110:28 28 34.37 0.04 4 11210110:29 29 34.35 0.06 5 11210110:30 30 34.34 0.07 6 112/0110:31 31 34.11 0.08 7 112/0110:32 32 34.32 0.09 8 11/2/0110:33 33 34.30 0.10 9 112/0110:34 34 34.29 0.12 10 ` IUIVI10:35 35 34.28 0.13 II 1120110:36 36 34.27 0.14 12 112.0110:37 37 34.26 0.15 13 r 1120110:38 38 34.25 0.16 W 11210110:39 39 34.24 0.17 IS • 11/210110:40 40 34.24 0.17 16 11/2101 10:41 41 34.23 0.18 17 1=110:42 42 34.22 0.19 18 1I 112!0110:43 43 34.21 0.19 19 1120110:44 44 34.20 0.21 20 t l IJ20110:49 49 34.17 0.23 25 1120110:54 54 34.13 0.28 30 1120110:59 112'0111:04 59 64 34.10 34.08 0,31 0.33 35 40 1120111:09 69 34.06 0.35 45 1120111:14 74 34.05 0.36 50 112'0111:19 79 34.04 0.36 55 p. 1120111:24 84 34.04 0.37 60 112!0111:34 94 34.01 0.40 70 11210111:44 104 31.96 0.45 80 112/0111:54 114 33.89 0.52 90 11210112:04 124 33.82 0.59 100 11210112:24 144 33.58 0.83 120 i 1120112:44 164 33.20 1.21 140 ` 11210113:04 184 32.74 1.67 160 112/0113:24 204 32.24 2.17 130 112/0113:44 224 31.71 2.70 200 11210114:34 274 30.16 4.25 250 11201 IS:24 324 23.45 596 300 1120117:04 424 24.69 9.72 400 1120118:44 524 21.61 12.80 500 1120120:24 624 18.96 15.45 6W 112'0122:04 724 16.04 18.37 700 1120123:44 824 13.87 20.54 800 11/3'011:24 924 12.09 22.32 900 11/3013:04 1024 10.89 23.52 1000 1113:014:44 1124 10,04 24,37 1100 11/3/016:24 1224 9.35 25.06 1200 1113/017:23 1283 8.97 25.44 1259 I LoT2 241aR mon.xls 12120/01 1 oft Aquifer Test Data -Lot 2, Villages View Estates Nest S/D n L . tri+ 1� " 11/3/017:24 1284 8.98 25.43 1260 Y s' sa' $(projected) t`s' Pump off Recovery 11/3/017:25 1285 9.09 25.32 1 25.32 0.00 25.32 1285.00 11131017:26 1286 9.09 25.32 2 25.32 0.00 25.32 643.00 11131017:27 1287 9.08 25.33 3 25.33 0.00 25.33 429.00 11/3/017:28 1288 9.08 25.33 4 25.33 0.00 25.33 322.00 ` 11/3/01729 1289 9.08 25.33 5 25.33 0.00 25.33 257.80 11131017:30 1290 9.08 25.33 6 25.33 0.00 25.33 215.00 $.. 11/3,01 7:31 1291 9.07 25.34 7 25.34 0.00 25.34 184.43 11/3,01792 1292 9.07 25.34 8 25.34 0.00 25.34 161.50 11/301793 1293 9.06 25.35 9 25.35 0.00 25.34 143.67 11/3/017:34 1294 9.06 25.35 10 25.35 0.00 25.35 129.40 11/3101 7:39 1299 9.07 25.34 15 25.34 0.02 25.16 86.60 11/3/017:44 1304 9.07 25.34 20 25.34 0.04 25.38 65.20 11/3/017:49 1309 9.08 25.33 25 25.33 0.07 25.39 52.36 1113/01 7:54 1314 9.10 25.31 30 25.31 0.09 25.40 43.80 1113/017:59 1319 9.11 25.30 35 25.30 0.12 25.42 37.69 11/31018:04 1324 9.14 25.27 40 25.27 0.16 25.43 33.10 I^ 1I/M18:09 1329 9.17 25.24 45 25.24 0.21 25.45 29.53 1113,018:14 1334 9.21 25.20 50 25.20 0.27 25.46 26.68 11/3018:19 1339 9.25 25.16 55 25.16 0.32 25.48 24.35 1113018:24 1344 9.29 25.12 60 25.12 0.37 25.49 22.40 11/3.018:34 1354 9.41 25.00 70 25.00 0.52 25.52 19.34 t� 11/3/018:44 1364 9.50 24.91 80 24.91 0.64 25.55 17.05 1113018:54 1374 9.65 24.76 90 24.76 0.82 25.58 15.27 l l 11/31019:04 1384 9.75 24.66 100 24.66 0.95 25.61 13.84 11/31019:24 1404 10.12 24.29 120 24.29 1.38 25.67 11.70 11131019:44 1424 10.56 23.85 140 23.85 1.88 25.73 10.17 11/3/0110:04 1444 11.09 23.33 160 23.33 2.45 25.79 9.03 1113/0110:24 1464 11.65 22.76 180 22.76 3.09 25.84 8.13 11/3101 10:44 1484 12.27 22.14 200 22.14 3.76 25.90 7.42 11/310111:34 1534 13.97 20.44 250 20.44 5.61 26.05 6.14 11/3,0112:24 11/3.0113:14 1584 1634 15.77 17.72 18.61 16.69 300 350 18.63 16.69 7.56 9.65 26.20 26.34 5.28 4.67 11/30114:04 1684 19.64 14.77 400 14.77 11.72 26.49 4.21 ` 1113101 15:44 1784 23.47 10.94 500 1094 15.84 26.78 3.17 11/3/011724 1884 26.98 7.43 600 7.43 19.64 27.07 3.14 111310119:04 1984 30.25 4.16 700 4.16 23.21 27.37 2.83 11/310120:44 2084 33.09 1.32 800 1.32 26.34 27.66 2.61 11/310122:40 2200 35.93 -1.52 916 -1.52 28.00 2.40 1114.'010:20 2300 37.09 -2.68 1016 -2.68 11/4,'012:00 2400 37.26 -2.85 1116 -2.85 11/4.01 3:40 2500 39.42 -5.01 1216 -5.01 11/4.015:20 2600 39.22 4.81 1316 4.81 11/4:017:00 2700 39.23 4.82 1416 4.92 11/4,01 12:00 3000 39.36 4.95 1716 4.95 11/4,0120:20 3500 39.09 4.68 2216 4.68 11/5,014:40 4000 38.76 4.35 2716 4.35 11/50111:20 4400 39.11 -4.70 3116 4.70 t� �I LoT2 241112 mon.sls 12120/01 2of2 I of 2 i Aquifer Test Data -Lot 3, Villages View Estates West S/D Source File: P:\20110D-I\AQUIFC•-1\3 2411R.DAT Location: Lot 3 - Production Well r. Start: 11/2101 10:07 AM L End: 1115101 11:15 AM . Date Minutes Feet of Water Drawdown n 11/2/01 10:07 0 312.00 0.00 Start Water Level Monitoring 11/2/0110:08 1 312.05 -0.04 11/210110:09 2 312.02 -0.02 11/210110:10 3 312.05 -0.04 11/2/0110:11 4 312.05 -0.04 11/2/0110:12 5 312.05 -0.04 11/2101 10:13 6 312.02 -0.02 Start Pump in Production Well 112/0110:14 7 309.36 2.64 L+ 112/0110:15 8 307.43 4.57 112101 10:16 9 305.79 6.22 11/210110:17 10 303.92 7.08 112/01 10:18 11 302.71 9.29 11/210110:19 12 300.61 11.40 I1/210110:20 13 298.57 13.43 112/0110:21 14 296.64 15.36 I1/2,0110:22 15 294.85 17.16 112/0110:23 16 293.07 18.93 112/0110:24 17 291.40 20.60 112/0110:25 18 289.73 22.27 112/0110:26 19 288.15 23.85 ■^ 112/0110:27 20 286.61 25.39 112/0110:32 25 279.72 32.28 11/2/0110:37 30 273.90 38.11 11/2,101 10:42 35 268.26 43.74 112/0110:47 40 262.93 49.07 11/2/0110:52 45 257.91 54.09 112/0110:57 50 253.34 58.67 112/0111:02 55 249.09 62.91 11210111:07 60 244.78 67.22 11/2/0111:17 70 237.05 74.96 11/2/0111:27 80 230.22 81.78 11/2/01 11:37 90 223.96 88.04 11/2/0111:47 100 218.33 93.67 11/2101 11:57 110 213.19 98.81 11/210112:07 120 208.34 103.66 11/2/01 12:17 130 203.99 108.02 112/01 12:27 140 199.81 112.20 112101 12:37 150 196.10 115.90 112/01 12:47 160 192.79 119.22 112/01 12:57 170 189.47 122.53 11/2101 13:07 180 183.71 128.29 11/2101 13:27 200 177.47 134.53 11/2/0113:47 220 171.95 140.06 I1/2/0114:07 240 167.94 144.06 �^ 11/2/0114:27 260 164.88 147.12 112/0115:07 300 158.63 153.36 112/0115:57 350 152.51 159.49 112/0116:47 400 148.16 163.84 r ' 11/2/01 18:27 500 140.95 171.06 112/0120:07 600 120.95 191.05 11/210121:47 700 112.98 199.03 11/2/0123:27 800 119.71 192.29 11/3/011:07 900 123.68 188.32 11/3/012:47 1000 118.20 193.80 11/3/015:48 1181 106.72 205.29 r' l LoT3 2411R_pump.xls 1220101 I of 2 Pump off= Recovery F. LoT3 241IR-pump.xls 12/20,'01 2of2 Aquifer Test Data -Lot 3, Villages View Estates West S/D I ' 11/3/015:49 1182 I06.65 205.35 s' t' Uf 11/3'015:50 1183 106.69 205.31 205.31 1 1183.0 ►•. 11/3/015:51 1184 106.72 205.29 205.29 2 592.0 11/3/015:52 1185 106.74 205.27 205.27 3 395.0 11/3/015:53 1186 106.82 205.18 205.18 4 296.5 11/31015:54 1187 106.78 205.22 205.22 5 237.4 11/3101 5:55 1188 106.87 205.14 205.14 6 198.0 11/3/015:56 1189 106.95 205.05 205.05 7 169.9 11/3/015:57 1190 106.98 205.03 205.03 8 148.7 11/3/015:58 1191 107.06 204.94 204.94 9 132.3 11/31015:59 1192 107.06 204.94 204.94 10 119.2 11/3/016:00 1193 107.11 204.90 204.90 11 108.5 11/3/016:01 1194 107.06 204.94 204.94 12 99.5 11/3/016:02 1195 107.08 204.92 204.92 13 91.9 n 11/3/016:03 1196 107.11 204.90 204.90 14 85.4 11/31016:04 1197 107.11 204.90 204.90 15 79.8 11/3/016:05 1198 107.19 204.81 204.81 16 74.9 11/3/016:06 1199 107.19 204.81 204.81 17 70.5 r+ 11/31016:07 1200 107.26 204.75 204.75 18 66.7 11/31016:08 1201 107.24 204.77 204.77 19 63.2 11/3/016:09 1202 107.28 204.72 204.72 20 60.1 11/3/016:14 1207 107.39 204.62 204.62 25 48.3 11/3/016:19 1212 107.95 204.05 204.05 30 40.4 11/3101 6:24 1217 108.75 203.25 203.25 35 34.8 11/31016:29 1222 109.62 202.38 202.38 40 30.5 11/3/016:34 1227 110.64 201.37 201.37 45 27.3 '+ 11/3/016:39 1232 112.13 199.87 199.87 50 24.6 1113/016:44 1237 114.00 198.01 198.01 55 22.5 11/3/016:49 1242 115.90 196.10 196.10 60 20.7 11/31016:54 1247 118.33 193.67 193.67 65 19.2 *' 11/3/016:59 1252 122.86 189.15 189.15 70 17.9 l 11/3/017:04 1257 127.99 184.01 184.01 75 16.8 ' 11/3/017:09 1262 132.95 179.05 179.05 80 15.8 11/3/017:19 1272 141.27 170.73 170.73 90 14.1 11/3/017:29 1282 148.55 163.45 163.45 100 12.8 11/3/017:39 1292 154.96 157.04 157.04 110 11.7 11/3/017:49 1302 161.03 150.98 150.98 120 10.8 11/3/01 7:59 1312 167.12 144.89 144.89 130 10.1 1113101 8:09 1322 172.96 139.04 139.04 140 9.4 11/3/018:29 1342 183.58 128.42 128.42 160 8.4 11/3/018:49 1362 192.98 119.02 119.02 180 7.6 11/31019:09 1382 201.45 110.55 110.55 200 6.9 ^ 11/31019:29 1402 208.99 103.01 103.01 220 6.4 11/31019:49 1422 215.84 96.17 96.17 240 5.9 11/3/01 10:29 1462 227.99 84.01 84.01 280 5.2 11/3/0111:09 1502 238.22 73.79 73.79 320 4.7 11/3/0111:49 1542 247.23 64.77 64.77 360 4.3 11/3/0112:29 1582 254.66 57.34 57.34 400 4.0 11/3/01 14:09 1682 269.11 42.89 42.89 500 3.4 11/3/0115:49 1782 279.14 32.86 32.86 600 3.0 " 11/3101 17:29 1882 286.18 25.82 25.82 700 2.7 lIl/3/0119:09 1982 291.25 20.75 20.75 800 2.5 11/310120:49 2082 295.17 16.83 16.83 900 2.3 11/3/0122:29 2182 298.33 13.67 13.67 1000 2.2 r" 11/41011:49 2382 302.86 9.14 9.14 1200 2.0 j 11/4/015:09 2582 305.70 6.30 6.30 1400 1.8 11/41018:29 2782 307.41 4.59 4.59 1600 1.7 11/4/01 11:49 2982 308.75 3.25 3.25 1800 1.7 11/410115:09 3182 309.66 2.34 2.34 2000 1.6 1114,10123:29 3682 311.16 0.84 0.84 2500 1.5 11/5/017:49 4182 312.05 -0.04 -0.04 3000 1.4 11/5/019:29 4282 312.11 -0.11 -0.11 3100 1.4 11/5/0111:09 4382 312.31 -0.30 -0.30 3200 1.4 Pump off= Recovery F. LoT3 241IR-pump.xls 12/20,'01 2of2 I of Aquifer Test Data -Lot 4, Villages View Estates West SID l.. Source File: PA20110D-I\ANTECE-IWANTDAT.DAT Location: Lot 4 - Monitoring Well Start: End: 10/3010113:16:18 10/31/01 17:26:18 Date Minutes Water Level 10/30/01 13:16 0 11.35 Start Water Level Monitoring 10/30/01 13:26 10 11.35 10/30/01 13:36 20 11.34 10/30/0113:46 30 11.34 10/30,0113:56 40 11.34 10/3010114:06 50 11.34 10/3010114:16 60 11.33 10/30/0114:26 70 11.33 10/30/0114:36 80 11.33 r I 10/30/0114:46 90 11.33 10/30/01 14:56 100 11.32 10/30/01 15:06 110 11.32 10/30/01 15:16 120 11.31 10/30;0115:26 130 11.31 10/30/01 15:36 140 11.30 10/30/01 15:46 150 11.29 10/30/01 15:56 160 11.28 10/30'0116:06 170 11.27 10/3001 16:16 180 11.26 10/30/01 16:26 190 11.25 10/30/0116:36 200 11.24 10/30/0116:46 210 11.23 10/3010116:56 220 11.22 10/3010117:06 230 11.21 10/30/0117:16 240 11.20 P` 10/30/01 17:26 250 11.19 10/3010117:36 260 11.18 10/3010117:46 270 11.17 10/3010117:56 280 11.17 10/30/01 18:06 290 11.16 10/30,0118:16 300 11.16 !!! 10/30'0118:26 310 11.15 10/30'0118:36 320 11.15 10/30'0118:46 330 11.15 10/30101 18:56 340 11.15 10/30/01 19:06 350 11.15 10/3010119:16 360 11.15 r. 10/30/01 19:26 370 11.15 10/30/0119:36 380 11.16 10/30/01 19:46 390 11.16 10/30/0119:56 400 11.17 10/30/01 20:06 10/30/0120:16 410 420 11.18 11.18 l t 10/3010120:26 430 11.20 10/3010120:36 440 11.20 10/3010120:46 450 11.21 10/30'0121:36 500 11.27 10/30,10123:16 600 11.35 10/31/010:56 700 11.38 10/31/012:36 800 11.37 A 10/31/014:16 900 11.35 G , 10/31/015:56 1000 11.26 10/31/017:36 1100 11.22 10/31/019:16 1200 11.30 .. 10/31/01 10:56 1300 11.41 10/31/01 12:36 1400 11.46 10/31/01 14:16 1500 11.46 10/31/01 15:56 1600 11.44 10/31/01 17:26 1690 11.35 Lot4 all data.xls 1212001 I of 2of3 Aquifer Test Data - Lot 4, Villages View Estates West SID Rc-Start Water Level Monitoring 10/31/0117:26 0 11.35 �^ I 10/31/01 19:06 10/31/0120:46 100 200 11.28 11.32 j 10/31/01 22:26 300 11.42 11/1/010:06 400 11.48 P. 11/1/011:46 500 11.50 11/1/013:26 600 11.49 11/1/015:06 700 11.45 11/1/016:46 800 11.35 11/1/018:26 900 11.33 11/1/01 10:06 1000 11.42 11/1101 11:46 1100 1132 11/l/01 13:26 1200 11.55 ll/l/01 16:46 1400 11.47 r 11/1/01 19:56 1590 11.27 f 11/1/01 23:26 1800 11.43 11/21012:46 2000 1IA8 11/2/016:06 2200 11.37 ^ 1112/019:26 2400 11.27 11/2'01 10:06 2440 11.31 Stan Pump in Production Well 11/2101 12:46 2600 11.47 11/2/0116:06 2800 11.52 ^ 11/2'0119:26 3000 11.36 1 11/2/0122:46 3200 11.49 11/3/012:06 3400 11.65 11/3/015:26 3600 11.65 Pump off 11/3/018:46 3800 11.49 11/3/01 12:06 4000 11.59 11/3/01 15:26 4200 11.59 11/3/01 20:26 4500 11.20 ^ 11/4'01 1:26 4800 11.22 11/41016:26 5100 11.08 111410111:26 5400 10.89 11/4101 16:26 5700 10.98 1114,10121:26 6000 10.71 II/5101 2:26 6300 10.86 11/5/01 7:26 6600 10.81 6860 10.72 r11/510111:46 1. 1. 1. Ir+ l; n. F i n Lot4 all data.xls 12/20/01 2of3 F C F r F. Aquifer Test Data - Lot 4, Villages View Estates West SID Date Date Pressure (Greenwich) (Anchorage) Millibars 1113/01 0:53 11/2'01 15:53 990.7 11/3/01 2:53 11/2/0I 17:53 990.6 11/3/014:53 1112'0119:53 989.9 1113/016:53 11/210121:53 988 11/3/018:53 11/2'0123:53 986.5 11/310110:53 11/3/011:53 985.8 1113/0112:53 11/3/013:53 983.4 1113/0114:53 11/3,'015:53 983.5 11/3/0116:53 11/3/017:53 982.4 11/3/0118:53 11/3/019:53 981.5 1113/01 20:53 11/3101 11:53 980.9 1113/0122:53 11/3'0113:53 980.8 11/4/010:53 11/3'0115:53 981.6 11/3,1012:53 11/3'0117:53 982.9 11/4'014:53 11/3'0119:53 985 11/4'016:53 110/0121:53 987.5 11/4/018:53 1113/0123:53 990.1 11/4'0110:53 11/4011:53 992.5 11/4'0112:53 11/4'013:53 994.8 11/4/0114:53 11/4015:53 996.7 11/4'0116:53 11/41017:53 998.7 1114101 18:53 11/4101 9:53 1000.6 111410120:53 11/4101 11:53 1002.4 11/410122:53 11/4!0 1 13:53 1003.8 11151010:53 11/4101 15:53 1005.1 1115/012:53 1114101 17:53 1006.6 11151014:53 11/4101 19:53 1007.9 11/5/01 6:53 11/4/0121:33 1009 1115/01 8:53 11/4/0123:53 1010 11/5/01 10:53 11/5/01 1:53 1010.7 11/5101 12:53 11151013:53 1010.8 1115101 14:53 11151015:53 1010.8 1115101 16:53 1115/01 7:53 1010.9 1115/01 18:53 11/51019:53 1011 111510120:53 1115/01 11:53 1011.2 111510122:53 1115101 13:53 1011.2 11/6101 0:53 11/5/01 15:53 1010.8 11/61012:53 1115/01 17:53 1010.3 11/61014:53 1115101 19:53 1010.2 11161016:53 11/5/01 21:53 1010 1116/01 8:53 1115101 23:53 1009.8 11/6101 10:53 11/6/01 1:53 1009.7 11/6/01 12:53 11/6/013:53 1009.9 11/6/01 14:53 11/6/01 5:53 1009.9 11/6/01 16:53 11/6/01 7:53 1010.3 1116101 18:53 11/6/01 9:53 1010.6 Start monitoring Barometric Pressure Pump off F. Lot3_all data.xls 12/20/01 3of3 9416' TERM"IT, INC. 1413 West 315t Avenue, Anchorage, AK 99503 (907) 344-.9370 Geological Consulting Environmental Restoration Regulatory Compliance Q 7 'JUL 1 0 2001 Ground Water Evaluation for the proposed Villages View Estates West Prepared for: Kin Shaw and Son Shaw P. O. Box 110637 Anchorage, AK 99511 By: TERRASAT, INC. 1413 West 31" Avenue Anchorage, AK 99503 June 20, 2001 TABLE OF CONTENTS INTRODUCTION.........................................................................................1 SiteDescription.............................................................................................................. I OBJECTIVES................................................................................................1 DATASOURCES..........................................................................................1 Aerial Photography & Geologic Maps.......................................................................... I WellLogs........................................................................................................................ I DATA INTERPRETATION........................................................................ 2 Aerial Photography & Geologic Maps.......................................................................... 2 LocalGeology................................................................................................................. 2 LocalHydrogeology....................................................................................................... 3 Aquifersand Well Yields............................................................................................... 3 BedrockOccurrence...................................................................................................... 3 CONCLUSIONS............................................................................................ 4 RECOMMENDATIONS.............................................................................. 4 PROFESSIONAL SIGNATURES...............................................................4 Figure 1 Figure 2 Figure 3 Figure 4 FIGURES Site Location Map Water Well Locations With ID Numbers Depth to Bedrock for Water Wells Within 'h Mile of VVEW Yields for Water Wells Within 'h mile VVEW APPENDICES Appendix A Well Log Summary INTRODUCTION Kin Shaw and Son Shaw contracted TERRASAT, INC to evaluate the ground water conditions in the Proposed Villages View Estates West Subdivision, Anchorage, Alaska. Our scope of services includes: • Estimating the water production potential for the proposed subdivision and potential impacts to surrounding well users based on the available hydrogeologic information. • Evaluating the aquifer conditions based on current available information for the area. • Making recommendations based on our findings to determine if additional investigation is warranted. Site Description The Proposed Villages View Estates West Subdivision is located east of the Villages Scenic Parkway, south of Potter Valley Road in Anchorage, Alaska (Figure 1). The sectional description for the area is the SW 1/4 Section 14, Township 11 North, Range 3 West, Seward Meridian. OBJECTIVES Our objectives for this project are as follows: • Estimate the potential of adequate water supplies for single-family wells on five lots in the Proposed Villages View Estates West Subdivision; • Determine the volume of water that will be considered adequate for a typical single- family home; 9 Estimate the potential impacts to water wells in the surrounding area. DATA SOURCES Aerial Photography & Geologic Maps TERRASAT, INC examined aerial photographs to gain an understanding of the regional geology. We examined both high-altitude color infrared photos to identify regional geological trends and low -altitude color photos to evaluate local features that may influence a or control the flow of ground water through the area. We also examined the United States Geological Survey's (USGS) Water Resources report entitled Hydrogeology for Land -Use Planning: the Potter Creek Area, Anchorage Alaska (USGS Water Resources Investigations Open -File Report 82-86, 1986). This report summarizes the surface geology of the Potter Creek area and contains maps that show the topographic slope and estimates of depth to bedrock for this region. Well Logs TERRASAT, INC acquired 16 driller's logs for water wells on file with the Department of Natural Resources (DNR), the Municipality of Anchorage On -Site Water and Wastewater Services, or on file with the United States Geological Survey. We tabulated information from the available well logs into a spreadsheet (Appendix A). Information provided by the PA20110-Village View\Reports\6-20-01 Village View report.doc Pagel of4 RF% logs includes total depth, well yield, depth to water, depth to bedrock, aquifer type, and well location. One or more parameters are missing for some of the wells. Using a geographical information system (GIS), we plotted the water well locations based on the DNR coordinate reference system of Section, Township and Range. We labeled wells according to an assigned index number from our database (Figure 2). The GIS system enables TERRASAT, INC. to make links between spatial data, well locations, and ancillary information such as elevation of the well, depth of the well, depth to bedrock, or the physical description of each well. The power of the GIS is that it allows us to create new maps based on queries of the ancillary information attached to each well location. We use these new maps to look for trends that may be hidden within the data. General practice for evaluating depth to ground water requires all water levels be measured in a very short time period, as static water levels may vary in response to stream levels, rainfall, pumping, and seasonal variations. Accurate measurement of water levels is important to determine the sources of water and to determine if flow paths change seasonally. Data from the driller's log represents water levels from different times, often years apart, thus is questionable, and may provide a poor representation of the static water levels in the area. DATA INTERPRETATION Aerial Photography & Geologic Maps Interpretation of local large-scale geologic features reveals that bedrock gently slopes to the west. At least one north -south linear feature was observed on the aerial photos about 0.4 miles east of the property. This feature is interpreted as a possible fault. Faults tend to be good conduits for ground water. The U.S.G.S. Water Resources Investigations Open -File Report 82-86 evaluates the ground water resources in the Potter Creek area. This report shows that an estimated 6-8 ft3 per second of ground water flows beneath the Potter creek area. The authors analyzed local precipitation amounts, local recharge, and compared these values to the amount of water flowing out of the Potter Creek area, discharge. They determined that the amount of water leaving the Potter Creek area as surface water, water lost to the atmosphere, or as ground water is more than the amount of recharge that results from annual precipitation. They conclude that a significant portion of the ground water that flows beneath the Potter Creek drainage basin comes from sources east of the valley higher up in the Chugach Range. Local Geology Our analysis of the well log data shows that most of the wells adjacent to the proposed subdivision have similar geology and construction. Based on our study, all of the wells located within '/2 mile of the proposed subdivision are completed in bedrock. Our study shows that all of the wells within this % mile radius, with exception of well number 12, encountered bedrock at depths of less than 20 feet. Well number 12 was drilled on a ridge of glacial deposits northeast of the proposed subdivision and encountered bedrock at a depth of 1" PA201 I O -Village View\Reports\6-20-01 Village View report.doe Page 2 of 4 50 feet. Depth to bedrock increases as a general trend as you move north from the proposed subdivision (Figure 3). TERRASAT, INC developed a conceptual geologic model for the Proposed Villages View Estates West Subdivision based on our review of the aerial photographs, hydrogeological reports, and available well logs. We conclude that the proposed subdivision is underlain by exposed bedrock or bedrock covered by a thin deposit of glacial till. The bedrock slopes gently to the west-northwest toward Turnigan Arm and Potters Creek. An intermittent stream appears to flow west from the property and the remaining drainage appears to flow to the northwest towards Potter Creek. Local Hydrogeology TERRASAT, INC developed a hydrogeological model of the area. Our model suggests that the dominant aquifer in this area is a bedrock aquifer. We believe that the ground water of the area is controlled by structures in the regional and local bedrock. The strongest control on bedrock aquifers is fractures and faults. Since the recharge for this aquifer appears to be from sources outside the Potters Creek drainage basin (U.S.G.S. Water Resources Investigations Open -File Report 82-86), we conclude that local topographic features have little affect on regional ground water flow. Aquifers and Well Yields Past ground water studies, conducted by TERRASAT, INC on the hillside in Anchorage, have suggested that most wells in bedrock aquifers will typically produce less than 0.5 gpm. This production rate is generally considered marginally adequate for single-family homes. The Municipality of Anchorage has determined that a well provides adequate water for a single family home if it produces 0.35 gpm (500 gallons per day) per bedroom. A well for a three-bedroom house, therefore, must produce just over 1.0 gpm to be considered adequate for a typical single-family home. Figure 4 shows the available well yield data for the residential wells within '/2 mile of the proposed subdivision. We have placed '/4 mile and 'h mile markers around the proposed subdivision to help illustrate that available yield data suggests that the bedrock aquifer in this area produce adequate flow rates for a typical single-family home. The average yield, based on the median value, for wells within '/4 mile of the proposed subdivision is approximately - 3.75 gpm. The average yield of wells within % mile of the proposed subdivision is approximately 3.91 gpm. Based on available well yield information, no wells with a yield of less than 1.0 gpm are known to exist within I/4 mile of the proposed subdivision. Only one well, Village Parkway Estates #1 Lot 4 (Well #3 in Figure 2), has a reported yield that is less than 2.0 gpm (1.5 gpm; Appendix A). Bedrock Occurrence Available logs show that all wells within 'h mile of the proposed subdivision intercept bedrock at depths varying from just below ground surface to 74 feet. These wells are cased to just below the bedrock and intercept to fractures at varying depths. The bedrock fractures are the apparent source of water for these wells. PA20110-Village View\Reports\6-20-01 Village View report.doc Page 3 of Conclusions The hydrogeology beneath the proposed subdivision is complex, but the ground water production ability of the area appears capable of supporting single-family wells. Residential water wells in the area surrounding the Proposed Villages View Estates West Subdivision have a minimum average yield of 3.75 gpm which is above the consumptive need for a typical three-bedroom, single-family home. Based on our geological and hydrogeological evaluation of the area, residential water wells in the proposed subdivision should have yields comparable to those in the surrounding subdivisions. We conclude that the aquifers identified in the surrounding area also likely underlie the Proposed Villages View Estates w� West Subdivision. These aquifers should produce adequate water for individual wells on each lot. Based on available information, the fracture systems exploited by local wells appear to be common throughout the area and are capable of producing usable quantities of water. Previous studies of this area suggest that significant recharge of the bedrock aquifers occurs from outside the local drainage basin. Potential impacts to surrounding water wells from development of the proposed subdivision will likely be insignificant. We cannot make this conclusion, however, with a high degree of certainty without evaluating aquifer test data for wells within the proposed subdivision. Recommendations TERRASAT, INC. recommends conducting an aquifer test within the proposed subdivision to evaluate the impacts to surrounding users. Based on well depths and construction, an aquifer test should be designed to include one pumping well and one or two observation wells. The production well should be pumped a minimum of 24 hours, followed by 24 hours of recovery. Wells should be pumped at a rate that creates 70% to 90% drawdown in the production well at the end of the 24-hour test period. Monitoring of all three wells should start one or more days prior to the start of the test and continue throughout a minimum 48- hour testing period. The observation wells should be located approximately 100 feet and 200 feet from the production well. Information gained from this type of aquifer test will allow us to more accurately evaluate the impacts on surrounding wells and estimate the expected future yield for the next 10 years. Please contact us at 344-9370 if you have any questions. Professional Signatures Bill Lawrence Senior Hydrogeologist JDan Young Certified Professional Geologist Ground Water Professional P:\20110 -Village View\Reports\6-20-01 Village View report.doc Page 4 of 4 3 a L CD 0 N n yI P 77 co y.i P F. M O N O O N CO Qi 4-J i OJ p>� L = LO 3 L O_ t� (Z 0 TOt U) :3 m W a 0 c rn A � W t CNw is P n yI P 77 co y.i P F. N CO i LO n yI P 77 co y.i P F. i 0 0 N 0 N Q7 C 7 n .�� ,. .. � ,f.:.. y A �. :. s.. P:• ... �E E CL CL Lo CN CN I�AmRrwml WIANA '.'4-1-U . ..... .... Q. CD C\i Lm M is CL 'r- r'n E 0 CL E 7a3 Cj um fo T�i fu to n Uj �E E CL CL Lo CN CN I�AmRrwml WIANA '.'4-1-U . ..... .... -3mil I to Q. CD C\i M is CL 'r- r'n E 0 CL E Cj Ln :2 LLO 0 � o (D . . C) r*4 V- n -3mil I to C\i M is la APPENDIX A Summary of Well Data Q E K E _ Q 0 J 7 mo m E I I O 0 N CD O O O CU CO N N N N N N N N N N O r LL L L L L L L L L L L L L L L L U- (A. 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