'* .. Report on PHASE I HYDROGEOLOGICAL STUDY OF THE PEACHLAND LANDFILL Submitted to: THE CORPORATION OF THE DISTRICT OF PEACHLAND Peachland, B.C. Submitted by: EBA ENGINEERING CONSULTANTS LTD. Kelowna, B.C. September, 1996 EBA File No. 0808-95-88369 The Corporation of the District of Peachland Phase I Hydrogeologcal Study of the Peachland Landfill TABLE OF CONTENTS 1.0 INTRODUCTION ....................................... 1 2.0 SITE DESCRIPTION ..................................... 1 3.0 INVESTIGATION METHODS ............................... 2 3.1 Site Reconnaissance ....................................... 2 3.2 Review of Published Information .......................... 2 3.3 Test Pit Excavation Program ............................. 2 3.4 Water Sampling Program ............................... 3 3.5 Soil Gradation Tests .................................. 3 4.0 RESULTS ............................................ 3 4.1 Surface Observations ................................. 3 4.2 Shallow Soil Conditions ................................ 4 4.3 Water Quality Testing Results ............................ 5 5.0 DISCUSSION OF RESULTS ................................. 7 5.1 Leachate Impact Assessment ............................. 7 5.1.1 Surface Water Quality in Peachland Creek ................ 7 5.1.2 Groundwater Quality ............................. 7 5.2 Considerations For Landfill Closure ........................ 9 5.3 Monitoring Considerations .............................. 9 6.0 CONCLUSIONS AND RECOMMENDATIONS .................... 10 03Septembe196/0808-95-88369 i EBA Engineering Consultants Ltd . The Corporation of the District of Peachland Phase I Hydrogeological Study of the Peachland Landfd FIGURES Figure 1 Area Plan and Water Sample Locations Figure 2 Aerial Photograph of Site (1992) Figure 3 Groundwater Elevations at Water Reservoir Figure 4 Landfill Legal Plan TABLES Table 1 Summary of Gradation Test Results For Soil Samples Table 2 Chemical Analysis Results From Preliminary Water Sampling Program APPENDICES Appendix A Photographs Appendix B Test Pit Records Appendix C Soil Gradation Test Results Appendix D Analytical Laboratory Reports Appendix E Water Balance Analysis and Leachate Impact Assessment on Peachland Creek . .. .. .. 03Septernber96l0808-95-88369 11 EBA Engineering Consultants Ltd. The Corporation of the District of Peachland Phase I Hydrogeological Study of the Peachland Landfill 1.0 INTRODUCTION This report presents the results of a Phase I hydrogeological study conducted by EBA Engineering Consultants Ltd. (EBA) for the Corporation of the District of Peachland (CDP) at the Peachland Landfill site. CDP operates the site for disposal of municipal solid waste from the Peachland area. It is operated by the CDP and has been in use for approximately 27 years. EBA understands that the site will probably be closed in the near future as part of the overall solid waste management plan for the Central Okanagan region. The Phase I hydrogeological study was carried out in accordance with the terms of reference supplied by CDP and EBA’s proposal dated August 11, 1995. Authorization to proceed was given by Mr. Dick Fletcher, P.Eng. of Urban Systems Ltd. in a letter dated November 29, 1995. The scope of the Phase I study involved a general overview of the site based on existing sources of information and limited site investigation using test pits. The primary concern identified in the terms of reference was the potential for leachate from the landfill to affect water quality in Peachland Creek where drinking water is obtained from a creek intake and reservoir system. 2.0 SITE DESCRIPTION The site is located approximately 3 km west of Peachland with access provided via Princeton Road (refer to Figure 1). The overall topographic slope in the landfill vicinity is southward towards Peachland Creek. The landfill has been developed in a crescent-shaped depression in the bedrock with a bedrock controlled knob located in the southeast part of the property, An aerial photograph of the site and surrounding terrain taken in 1992 is presented on Figure 2. The surface water intake and water supply reservoirs are located 500 m south and downslope from the landfill. The legal description of the landfill and its boundaries relative to surrounding district lots is presented on Figure 4. The total area of the property as identified on the legal plan is approximately 14.77 ha. Based on the developed area shown on the aerial photograph, approximately 30% of the total property area or about 4.5 ha has been filled. Photographs collected during the site reconnaissance and field investigations are presented in Appendix A. A view of the developed landfill area and surrounding slopes is shown on Photo No. 1. The water reservoir on Peachland Creek is shown on Photo No. 7. Two springs were observed east of the landfill and adjacent to Princeton Road during the site reconnaissance. One of these springs (Spring No. 1, Figure 2) appears to be used for drinking water as evidenced by drinking cups located at the discharge (refer to Photo No. 6). 03September96/0808-95-88369 1 EBA Engineering Consultants Ltd. The Corporation of the District of Peachland Phase I Hydrogeologcal Study of the Peachland Landfill ... 3.0 INVESTIGATION METHODS 3.1 Site Reconnaissance A site reconnaissance was performed by EBA personnel during January, 1996. This included an inspection of the landfill property, discussions with CDP operations personnel at the site, marking test pit locations, identifying springs and surface water courses and inspection of soil exposures in borrow areas being utilized for landfill cover materials. 3.2 Review of Published Information EBA reviewed published information from the following sources: 0 “Late Glacial History and Surficial Deposits of the Okanagan Valley, British Columbia” Bulletin 46, British Columbia, Ministry of Energy, Mines and Petroleum Resources (Hugh Nasmith, 1981); and 0 “Historical Streamflow Summary for British Columbia’’ to 1986 published by Inland Waters Directorate, Ottawa Additional information considered in EBA’s study included 1:20,000 scale topographic mapping and climate information. A request was made to the Groundwater Section of B.C. Environment in Victoria for any water well information on file for the area within approximately 3 km of the site. However, they have no water well records on file for this area. 3.3 Test Pit Excavation Program The test pit excavation program was carried out on January 11, 1996. Test pits were excavated at seven locations selected by EBA using an Hitachi EX120 tracked excavator. Mr. R. Deans of EBA recorded the soil and groundwater conditions in the test pits and collected soil samples from selected locations for further examination and testing in EBA’s geotechnical laboratory in Kelowna. The approximate locations of the seven test pits (TP-1 through TP-7) are shown on Figure 2. Five test pits (TP-1 through TP-5) were excavated adjacent to the southern and eastern boundary of the landfill to investigate soil conditions and identify the presence of any shallow seepage. Two test pits (TP-6 and TP-7) were excavated adjacent to the water reservoirs to determine the water table elevation relative to the water surface in the reservoir (Le. to determine if the reservoir is losing or gaining water from the ground) and to provide for collection of shallow groundwater samples from standpipes placed in the backfilled test pits. 03September96/0808-95-88369 2 EBA Engineering Consultants Ltd. * .I The Corporation of the District of Peachland Phase I Hydrogeological Study of the Peachland Landfill 3.4 Water Sampling Program The water sampling program was carried out by EBA personnel between the dates of January 23 and 25, 1996. A total of 11 stations were sampled and a description of each sample location is provided on the inset table on Figure 1. These included four locations along Peachland Creek, Okanagan Lake, the main water reservoir, two shallow springs and a surface seep, and test pits TP-6 and TP-7 located adjacent to the reservoir. At each sample station, water temperature, pH and electrical conductivity were recorded in the field using calibrated, portable meters. Additionally, duplicate water samples were collected for laboratory analysis of electrical conductivity and chloride. Both electrical conductivity and chloride are useful indicator parameters to identify changes in water quality that may result from mixing of landfill leachate with the groundwater system. These parameters are normally elevated in landfill leachate and any leachate plume migrating from the landfill relative to concentrations in natural groundwater. Water quality sampling was carried out during January, 1996. The flow in Peachland Creek is normally at its seasonal low during this month based on historical records from the Inland Waters Directorate. Flow in Peachland Creek can be considered to consist of a component fed by groundwater discharge (baseflow) plus a component fed by surface runoff. The baseflow component remains relatively steady throughout the year while the runoff component varies considerably with precipitation and snowmelt. Since any groundwater containing leachate discharging to the creek would best be identified when the creek discharge is at a minimum, in years of normal flow, January would be the best month to conduct the sampling. As we understand that monitoring of creek flows is no longer carried out at the mouth of Peachland Creek, monitoring information is not available for the sample collection