Twin Lakes Basin Hydrogeological Study, Kaleden, BC
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.. .. .. .. .. .. ... , . .- . ., . , .,. .. .. .. 5 ,*' EBA Engineermgr3 Ltd, t -, TWIN LAKES BASIN HYDROGEOLOGICAL STUDY EBA FILE NO: 0808-88654 I J e e.1420 Hunter Court, Kelowna. B.C. V1X 6E6 em Telephone (604) 8624832 FAX (604) 862-2941 TWIN LAKES BASIN HYDROGOLOGICAL STUDY KALEDEN, B.C. Submitted to: TWIN LAKES GOLF & COUNTRY RESORT KALEDEN, B.C. Submitted by: I EBA ENGINEERING CONSULTANTS LTD. Kelowna, B.C. October, 1994 0808-88654 em EXECUTIVE SUMMARY I Twin Lakes Golf Resort is proposing a residential ,development on slopes overlooking the golf course, The proposal calls for approximately 256 single family residential units. Historically, development proposals in the Twin Lakes basin have raised objections primarily because of the concerns that water resources in the basin will be depleted. Recognizing the need to have water resource concerns addressed, Twin Lakes Golf Resort retained the services of EBA Engineering Consultants Ltd (EBA) of Kelowna, B.C. to undertake a hydrogeological study of the Twin Lakes basin. The purpose of the study being to determine whether water of adequate quantity and quality is available in the Twin Lakes basin to support the proposed development without causing unacceptable impacts. After a review of available information it became clear that detailed water basin and hydrogeological studies had not been completed for previous developments and should be done to properly assess the feasibility and potential impacts of the current development proposal. Further, it was clear that sufficient information on water chemistry in the Twin Lakes area was not available to meet the objectives of the study. Therefore, EBA embarked on a study aimed at investigating the water balance of the Twin Lakes basin, the hydrogeology in the vicinity of the golf course, and the water chemistry of ground and surface water in the study area. The study has concluded that groundwater of sufficient quantity is available to support the proposed development and further if certain design assumptions and concepts are applied to the proposed development, little or no increase in net water withdrawal from the basin can be accomplished. Twin Lakes Golf Resort has indicated that they intend to apply such designs and concepts in order to achieve, as a development objective, little or no increase in net water withdrawal. With regard to water quality, the study has concluded that there is a need for water treatment to reduce levels of mineralization and also prevent unacceptable impac'ts to vegetation and the groundwater regime when the water is returned to the golf course via a spray irrigation concept. It is further concluded that in order to reduce the level of hardness, total dissolved solids and certain dissolved species, community water treatment must be implemented rather than allow individual household treatment techniques such as water softening which exchange rather than reduce dissolved constituents. c em TABLE OF CONTENTS I i PAGE EXECUTIVE SUMMARY 1.0 INTRODUCTION . , . 1 2.0 BACKGROUND ........................................ 2 3.0 PROPOSEDDEVELOPMENT ............................ 2 i 3.1 Proposed Residential Concept . 3 3.2 Proposed Servicing Concepts . , . 3 4.0 SCOPEOFWORK ....................................... 4 5.0 WATERBALANCE ................................... 4 5.1 General . , . 4 5.2 Description of Twin Lakes Basin . 5 5.3 Estimation of Climatic Data . , . , . , . 6 5.4 Precipitation, Evapotranspiration and the Basin Water Balance . 8 6.0 AQUIFER TRANSMISSIVITY AND ESTIMATED GROUNDWATER FLOW . , . 11 6.1 Aquifer Geometry and Gradient . , . , . 11 6.2 Estimation of Aquifer Transmissivity . 12 6.3 Estimated Groundwater Flux and Seepage Velocity . 15 i -4 -1 TABLE OF CONTENTS (con%) PAGE 7.0 PRESENT AND PROPOSED WATER USAGE .................. 16 7.1 Present Water Usage in the Twin Lakes Basin ............... 16 7.1.1 Domestic Water Use .......................... 16 7.1.2 Irrigationusage.. ........................... 17 7.1.3 Total Present Water Usage ...................... 19 7.2 Effects of Proposed Development ...................... 19 1 8.0 EVALUATION OF C1 WELL ............................ 21 9.0 EVALUATION OF GROUNDWATER QUALITY ................ 24 10.0 SUMMARY AND CONCLUSIONS ......................... 25 11.0 LIMITATIONS OF LIABILITY ............................ 28 APPENDICES TABLES FIGURES I APPENDIX A - Water Balance Analysis J APPENDIX B - Water Well Logs 1 I APPENDIX C - Pump Test Data and Analysis I - C-1 - Main Well I - C-2 - New Highway Well I - C-3 - C1 Well I I I APPENDIX D - Water Chemical Analysis Reports 1 et3a . 0808-88654 f Page 1 October 31, 1994 1.0 INTRODUCTION This report presents the results of a hydrogeological investigation of the Twin Lakes area. Twin Lakes is an area, located approximately 25 kilometres south-west of Penticton, B.C., which is characterized by two nearby lakes. The lakes appear to be known by more than one name however, for the purposes of this report, the southern lake will be referred to as Upper Twin Lake (also Horn Lake), while the northern lake will be referred to as Lower Twin Lake. Historically, the area was used for ranching. More recently, residential development near and adjacent to Lower Twin Lake, and golf Course development (Twin Lakes Golf Resort) north of the lakes has gradually changed the land use characteristics of the area. EBA Engineering Consultants Ltd. (EBA) were retained in February, 1994, by Twin Lakes Golf Resort to investigate the hydrogeology of the Twin Lakes area. The purpose of the investigation is to determine groundwater feasibility and impacts of a proposed residential development, which is planned to be located on the property immediately east of the golf course. The history of development in the Twin Lakes area has always involved groundwater and water supply issues. Therefore, it is necessary that the groundwater conditions in the Twin Lakes basin, see Figure 1, be studied and understood in order to determine if the proposed development can proceed without causing unacceptable groundwater impacts. The hydrogeological investigation proposed by EBA was undertaken in two stages. The first stage involved a review of available information, some limited soils investigation and identification of critical issue related to the proposed development. A Stage 1 Report was prepared and submitted in May, 1994. That report included recommendations for a detailed Stage 2 investigation which would address the identified critical issues, analyze the hydrogeological regime and quantify any groundwater impacts of the proposed development. The Stage 2 investigation began in June, 1994, and was completed in October, 1994. This report presents the findings of the investigation and provides a quantitive assessment of groundwater issues related to the proposed development. c eDa t ‘ 0808-88654 Page 2 October 31, 1994 4a 2.0 BACKGROUND i The Twin Lakes area was historically a ranching area, largely controlled by three ranches. The location of Twin Lakes Golf Resort was at one time cultivated for hay production by the lower of the three ranches. During the 196O’s, recreational use of the area increased as subdivision took place around Lower Twin Lake. Subdivision around the lake has continued to present day resulting in a large number of rural zoned residential lots surrounding the lake, except for a large portion of the western side of the lake. Some large holding lots and multi-residence land use contract areas have also been created adjacent to Lower Twin Lake. The Twin Lakes Golf Resort was initially developed as a nine hole course in 1975, on the lower portion of the existing course adjacent to Highway 3A. A second development expanding the course to 18 holes occurred in 1985. A five lot subdivision occurred at the southern boundary of the golf course in 1991. An additional six lot subdivision at the southern edge of the golf course was completed in July of this Year. It is clear from review of available documents that concerns and disputes over the use of water in the Twin Lakes basin have dated back to the 1940’s and possibly earlier. Higher and lower lake levels appear to have resulted from periods of greater and lesser than normal precipitation. Available documents indicate that concerns and objections have consistently been raised with each development proposal including the subdivisions around Lower Twin Lake and the development of the Twin Lakes Golf Resort. The common theme to the concerns and objections has been the opinion that water resources will be depleted and that a detailed and thorough water basin analysis is required to assess the feasibility of any proposed development. 3.0 PROPOSED DEVELOPMENT 9 i I The development which is being planned and proposed by Twin Lakes Golf Resort is located on the eastern slopes overlooking and bordering the golf course. A layout of the development is illustrated in Figure 2. ' 0808-88654 i Page 3 October 31, 1994 3.1 Proposed Residential Concept The proposed development is entirely residential with a mixture of single family homes and townhomes. We understand the current configuration involves 172 homes, 48 two bedroom townhomes and 36 three bedroom townhomes. The 172 homes will include two, three and possibly four bedroom units. We further understand that the development will be a strata title development. It became clear very early in the hydrogeological investigation that any proposed development should incorporate water conservation measures to minimize or prevent impacts on the groundwater