5107-5119 Main St & 196 E 35Th Preliminary Hydrogeological Report

220 - 18 Gostick Place P: 604-990-0546 North Vancouver, BC F: 604-990-0583 Canada V7M 3G3 www.horizoneng.ca

PRELIMINARY HYDROGEOLOGICAL STUDY

Proposed Multi-Family Development 5107-5119 Main Street & 196 East 35th Avenue Vancouver, BC

Our File: 120-4724

August 10, 2020

TABLE OF CONTENTS 1.0 INTRODUCTION ...... 1 2.0 SITE INFORMATION ...... 1 2.1 Referenced Documents ...... 1 2.2 Site Description ...... 1 2.3 Existing Buildings ...... 2 2.4 Site Grades ...... 2 2.5 Proposed Development ...... 2 3.0 BACKGROUND INFORMATION ...... 3 3.1 Surficial Geology ...... 3 3.2 Groundwater Records ...... 5 3.2.1 Quadra Sands Aquifer ...... 5 3.2.2 Well Records Search ...... 6 3.3 Existing Boreholes ...... 9 3.4 Existing Watercourses ...... 9 4.0 SUBSURFACE INVESTIGATION ...... 9 4.1 Soil Conditions ...... 10 4.1.1 Fill / Topsoil ...... 10 4.1.2 Organic Silt ...... 10 4.1.3 Sand to Silt / Sandy Silt to Silty Sand ...... 10 4.1.4 Sand (till-like) ...... 10 4.2 Groundwater Conditions ...... 10 4.3 Proposed Supplementary Investigation and Field Works ...... 10 4.3.1 Supplementary Field and Lab Works ...... 11 5.0 GROUNDWATER MANAGEMENT PLAN ...... 11 5.1 Foundation Type ...... 11 5.2 Temporary Dewatering (During Construction) ...... 12 5.3 Long-Term Dewatering (Following Construction) ...... 12 6.0 IMPACT ASSESSMENT ...... 12 6.1.1 Lowered Water Levels and Ground Subsidence ...... 12 6.1.2 Environmental ...... 13 6.1.3 Water Quality, Fish, Wildlife, Ecosystems ...... 13 6.1.4 Artesian ...... 13 6.1.5 Flooding ...... 13 6.1.6 Erosion ...... 14 6.2 Avoidance / Mitigation Measures ...... 14 7.0 REVIEW ...... 14 8.0 CLOSURE ...... 15

Consulting Geotechnical Engineers ©Horizon Engineering Inc. Proposed Multi-Family Development Our File: 120-4724 5107-5119 Main Street & 196 East 35th Avenue, Vancouver, BC August 10, 2020 Preliminary Hydrogeological Study Page iii LIST OF TABLES Table 1: Flowing Artesian Groundwater Wells Records (generally listed from west to east) ...... 6 Table 2: Well Records Near Subject Site ...... 7 Table 3: Oakridge Mall Well Records Summary ...... 7 Table 4: Oakridge Mall Planned Temporary Dewatering Wells ...... 8 Table 5: Langara Golf Course Well Records Summary ...... 8

LIST OF FIGURES Figure I: Plan location of subject site (red circle) showing surficial geology and proximity to Section B-B’...... 3 Figure II: Plan location of subject site (red circle) showing 'Groundwater Areas of Concern'...... 4 Figure III: Partial Section B-B’ from Geological Survey of Canada Map 1486A...... 5

APPENDICES Appendix A: Figures > Figure 1: Site Location Plan > Figure 2: Test Hole Location Plan Appendix B: Test Hole Logs Appendix C: Submission Checklist for Hydrogeological Studies

1.0 INTRODUCTION This document reports on the results of the preliminary hydrogeological study carried out for the subject site and is intended to support the Re-Zoning Application for the proposed development. This report has been prepared in general conformance with our emailed supplementary scope of services dated May 22, 2020. This document has been developed to satisfy the requirements of the City of Vancouver Groundwater Management Bulletin (amended April 20, 2020) Section 2.3.2 and Appendix A. The subject site is within the Cambie Corridor Sewershed 'groundwater area of concern'.

2.0 SITE INFORMATION

2.1 Referenced Documents We have been provided with the following documents for the subject site: • Pre-Application Drawings prepared by Integra Architecture Inc., dated September 24, 2018, and • Little Mountain Adjacent Area Rezoning Policy for the City of Vancouver.

We have also referred to the following, publicly accessible sources to collect additional information in the vicinity of the subject site: • City of Vancouver Online Geographic Information Systems (GIS), • Geologic Survey of Canada Map 1486A, • Vancouver’s Old Streams Map, • Province of British Columbia well records and aquifer summaries described herein, and • others, as available and noted in this report.

2.2 Site Description The subject site is located in the “Little Mountain Adjacent Area” of the City of Vancouver and comprises three, single-family residential lots with civic addresses 5107 and 5119 Main Street and 196 East 35th Avenue in Vancouver, BC. The overall property is approximately rectangular in shape with overall dimensions of approximately 33 metres (110 feet) in the east-west direction by 30 metres (100 feet) in the north-south direction. As shown in Figure 1 attached to this report, the site is bounded by East 35th Avenue to the north, Main Street to the east, the proposed 'Little Mountain' development site (by others) to the south, and a paved lane (indicated to be approximately 6 metres wide) in turn bounded by an existing 6- storey building with a below-grade parkade to the west. The site area is understood to encompass a footprint of approximately 1,011 square meters (10,886 square feet). The site is adjacent to the proposed 'Little Mountain' site, a social housing redevelopment site by BC Housing. It is understood that the area of the 'Little Mountain' site at the south of the subject site will be developed with multi-family building with two levels of below-grade parking. At the south side of the property, an at-grade pedestrian thoroughfare is proposed; it is understood that this will be located half on the subject property and half on the neighbouring redeveloped 'Little Mountain' site (for a total pathway width of 3.0 metres).

2.3 Existing Buildings The subject site is currently occupied by three single family houses founded at-grade. Each of the houses fronts on Main Street and are set back from the property line on all four sides. The existing houses are generally located in the centre of each of the three existing lots which each have approximate dimensions of 33 metres (110 feet) in the east-west direction by 10 metres (33 feet) in the north-south direction.

2.4 Site Grades Topography within and in the vicinity of the site is generally flat. Within the property, site grades generally vary from El. 78 metres (256 feet) at the east portion of the site to El. 77 metres (252 feet) at the west portion of the site (CVD28GVR2018 datum).

2.5 Proposed Development Based on the aforementioned architectural drawings, we understand that the proposed development comprises a six-storey residential building founded over a two-level below grade parkade, which is envisaged to extend to within close proximity to the west, north, east, and east portion of south property lines. It is understood that the parkade along the west portion of the south property line (i.e., adjacent to the access ramp) will be set back approximately 3.7 metres (12 feet). The area encompassed by the excavation is expected to be on the order of approximately 850 square metres (9,500 square feet). Proposed excavation and foundation depths are expected to be in the range of 6 to 7 metres (20 to 25 feet) below existing grades with slab-on-grade elevations ranging from El. 70 to 72 metres (El. 230 to 236 feet) (CVD28GVR2018 datum). Based on the architectural drawings of the subject site, the proposed two-level underground parkade for the neighbouring building to the south is shown to be set back 3.5 metres from the shared property line.

3.0 BACKGROUND INFORMATION

3.1 Surficial Geology Based on published information available from the Geological Survey of Canada (Map 1486A), the subject site is located within an area where Vashon Drift and Capilano Sediments [VCb] can be expected near surface as shown in Figure I.

Figure I: Plan location of subject site (red circle) showing surficial geology and proximity to Section B-B’.

In the vicinity of the subject site, Vashon Drift and Capilano Sediments is expected to comprise glacial drift including lodgement and minor flow till, lenses and interbeds of substratified glaciofluvial sand to gravel, and lenses and interbeds of glaciolacustrine laminated stony silt, up to 25 metres thick; overlain by glaciomarine and marine deposits normally less than 3 metres but in places up to 10 metres thick. Bedrock is anticipated to be more than 10 metres below surface. We have also reviewed the Vancouver's Old Streams and the Peat, Assorted Soils, and Historical Waterways maps. These maps indicate that the subject site is not situated within a ‘peat zone’ or a ‘soil liquefaction zone’ or within the vicinity of any documented buried streams. The subject site is located within the Cambie Corridor Sewershed 'groundwater area of concern' per Figure II.

Figure II: Plan location of subject site (red circle) showing 'Groundwater Areas of Concern'1.

Based on the anticipated depth of excavation to facilitate below-grade construction, it is envisaged that the subject development will not encounter the Vancouver Quadra Sands artesian aquifer underlying the site during excavation. Additionally, the subject site is not located within the Well Drilling Advisory area defined by the Ministry of Environment. Section B-B’ of Geological Survey of Canada Map 1486A, which is located approximately 0.5 km west of the site (shown in Figure I above), provides additional information as to the subsurface geology at the subject site. This section, shown in Figure III, indicates that the geology in this location is expected to comprise VCb [Vashon Drift and Capilano Sediments], underlain by PVa [Pre-Vashon Quadra Sands], in turn underlain by older Pre-Vashon and/or Tertiary bedrock deposits.

1 City of Vancouver, accessed July 2020: https://maps.vancouver.ca/portal/apps/webappviewer/index.html?id=ba64dbf9a80341aa8527538fe55da80e

Figure III: Partial Section B-B’ from Geological Survey of Canada Map 1486A. Approximate projected location of the subject site is shown by the red arrow. Vashon Drift is a glacial deposit that ranges in age from about 13,000 to 18,000 years old and is composed of till, glaciofluvial, glaciolacustrine, and other ice-contact deposits. Pre-Vashon deposits in the general vicinity of the subject site are expected to consist of various glacial and interglacial deposits consisting of the following lithostratigraphic units. Quadra Sand ("PVa" as indicated on Figure III) which was deposited about 18,000 to 26,000 years ago, is expected to be encountered below the Vashon Deposit and to consist of “fluvial channel fill and floodplain deposits, cross-bedded sand containing minor silt and gravel lenses and interbeds”.

3.2 Groundwater Records 3.2.1 Quadra Sands Aquifer The British Columbia Ministry of Environment has identified the Quadra Sands Aquifer (Aquifer 49) that underlies most of the cities of Vancouver, Burnaby, and New Westminster. This aquifer is estimated to cover an area of about 195 km2 and is situated in Quadra Sands. This aquifer is categorized as Confined sand and gravel - glacial and is considered to have moderate vulnerability and moderate productivity2. Reportedly, based on 14 wells, the depth to water (inferred to be the top of the aquifer) ranges from about 5 to 87 metres (17 to 285 feet) with a mean of 37 metres (120 feet). Median and average depths to water are both reported as 46 and 47 metres (151 and 153 feet), respectively. There is no listing regarding the direction of groundwater flow, recharge, or domestic well density of this aquifer. Detailed well records indicate well yield rates of up to 202 US gallons per minute with average and median yield rates of 49 and 25 US gallons per minute3. We have reviewed the BC Ministry of Environment Well Drilling Advisory4 regarding flowing artesian conditions and information in the City of Vancouver’s Online Geographic Information System (GIS) regarding flowing artesian conditions, which indicates that the subject site is not within an area known to produce flowing artesian conditions. The Well Drilling Advisory indicates that the depth to the flowing artesian groundwater ranges from 25 metres to 73 metres below

2 Province of British Columbia, Aquifer 49 Summary: https://apps.nrs.gov.bc.ca/gwells/aquifers/49 3 Aquifer Classification Work Sheet, October 18, 2007: https://s3.ca-central-1.amazonaws.com/aquifer- docs/00000/AQ_00049_Aquifer_Mapping_Report.pdf 4 Well Drilling Advisory, October 2017: https://www2.gov.bc.ca/assets/gov/environment/air-land- water/water/water-wells/flowing_artesian_advisory_-_vancouver_bc_final.pdf

grade, which is expected to be well below the contemplated depths of the proposed development as well as the depth of influence which could be expected to potentially impact excavation for a two-level parkade. Detailed well records indicate that flowing artesian groundwater has been encountered at the six locations listed in Table 1. Table 1: Flowing Artesian Groundwater Wells Records (generally listed from west to east)

Date Correlated Aquifer Artesian Flow Finished Well Est. collar Distance from Location Well Tag # Drilled * (US gpm) Depth, m (ft) El.,** m site, km Uncorrelated N/A 7084 Beechwood 110406 Sep 2015 (within defined 250 Total depth drilled: 40 4.5 Street, Vancouver boundary of 49) 25 (82) Uncorrelated 8440 Cambie Street, 107740 Oct 2010 (not within any 0.01 73 (239) 14 3.5 Vancouver defined boundary) East Side of 8th Tee, Fraser View Golf 75276 Feb 1996 49 (Quadra Sands) 1.0 86 (283) 30 5.0 Course, Vancouver 6074 Marine Drive, 45 (Fraser River 74061 Mar 1993 0.01 31 (103) 10 10.0 Burnaby Sediments) Royal Columbian Uncorrelated Hospital, 113313 Jul 2017 (within defined 25 26 (85) 19 15.5 New Westminster boundary of 49) Uncorrelated Brunette Avenue, 117728 Jul 2019 (within defined 65 85 (280) 20 15.5 New Westminster boundary of 49) Douglas Street, 18810 Sep 1964 49 (Quadra Sands) 0.01 23 (76) 11 17.5 Port Moody * Correlated aquifer to subject well, if determined, per Province of British Columbia5 information. Uncorrelated aquifers have not been linked to a specific aquifer by the Province but may be within the defined aquifer boundary. Note: One well is correlated to Aquifer 45 (Fraser River Sediments), which does not underlie the subject site. ** Elevation data from Google Earth Pro and for reference/information only; this should not be used for any analysis; geodetic is assumed although no datum is provided. It is noted that all the above-listed flowing artesian groundwater wells are generally located around the south, east, and northeast sides of the Vancouver Quadra Sands Aquifer. No flowing artesian groundwater conditions have been recorded at wells located in proximity to the subject site, based on available information. 3.2.2 Well Records Search We have obtained publicly available well records for the existing wells in the general vicinity of the subject site listed in the water well records database made available by the Ministry of Environment. These wells are listed in Table 2 below.

5 Aquifer 49 Summary, accessed July 2020: https://apps.nrs.gov.bc.ca/gwells/aquifers/49

Table 2: Well Records Near Subject Site

Distance Date Flow Finished Well Location from site Well Tag # Type Drilled (US gpm) Depth, m (ft) (km) Construction 5110 Cambie Street* 1.0 117609 n/a n/a ~6 (20) dewatering 885 Cambie Street** 1.4 116135 July 2018 Closed Loop Geo n/a n/a 4480 Oak Street 1.9 101008 July 1997 Water Supply n/a 48 (158) 454 East 16th Avenue 2.0 116114 Sept 2017 Closed Loop Geo n/a n/a * Note: Address on general well page is incorrect; correct address taken from attached application form6. **Note: Coordinates (used) do not match street address provided. No well information available at time of research.

Additionally, there are a total of 10 well locations at Oakridge Mall, six planned temporary dewatering wells at Oakridge Mall, and four well locations at the Langara Golf Course, generally located 1.5 km and 2.0 km southwest of the subject site, respectively. Information contained within the well logs for these amenities is summarized following. Drill holes for these wells reportedly did not encounter flowing artesian conditions. 3.2.2.1 Oakridge Mall Available records indicate that ten wells were installed at Oakridge Mall, including three ‘Test Wells.’ The wells are reported to have been installed between May and July 1958. The subject wells were of various diameters and reported to be advanced to depths of 24 to 34 metres (80 to 111 feet), with casings reported to be advanced to depths of 18 to 24 metres (58 to 77 feet). The water depths in the well holes were reported to be between 5.9 and 7.0 metres (19.4 and 23.0 feet) below grade at the time of well installation. Well screens of between 4.6 and 8.2 metres (15 and 27 feet) long were installed within the various wells, from depths varying between 17.7 to 31.7 metres (58 to 104 feet). Well logs indicate that pump tests were carried out on seven of the wells. Information contained within the available logs is summarized in Table 3 below. Table 3: Oakridge Mall Well Records Summary

Well Information Pump Test Bot. of Hole Depth to Screen Pumping Installation Hole diam. casing Yield Well ID Field Log ID depth water Length Level Date cm (in) depth L/min (gpm) m (ft) m (ft) m (ft) m (ft) m (ft) 24.0 to 31.7 71194 Well 2 (No.1) July 1958 25 (10) 24 (79) 32 (105) 6.7 (22.0) 1,500 (400) 15.5 (50.9) (79 to 104) 18.6 to 24.7 71195 Well 6 (No.4) June 1958 40 (16) 18 (58) 25 (81) 6.4 (21.0) 550 (150) 11.5 (37.8) (61 to 81) 21.0 to 25.6 71196 Well 1 (No.2) May 1958 30/40 (12/16) - 26 (84) 6.5 (21.2) 1,500 (400) 13.8 (45.2) (69 to 84) 21.6 to 29.0 71197 Well 7 (No.3) July 1958 40 (16) 21 (69) 29 (95) 6.4 (21.0) 750 (200) 13.8 (45.3) (71 to 95) 22.3 to 30.5 71198 Well 4 (No.5) June 1958 40 (16) 22 (71) 30 (100) 7.0 (23.0) 1,650 (435) 14.5 (47.5) (73 to 100)

6 British Columbia Use Approval (Short Term Use of Water) - Tracking Number: 100287963.

71201 Test Well T2 - 20 (8) - 33 (108) 6.3 (20.8) - - -

108181 Test Well T3 - 20 (8) - 34 (111) 6.4 (20.9) - - -

108182 Test Well T5 - 20 (8) - 32 (107) - - - -

It is understood that pumping from these wells is ongoing in order to provide cooling for the Oakridge Mall; this activity is envisaged to significantly control porewater pressures in this stratum. Additionally, six temporary dewatering wells are indicated to be planned for the Oakridge site, as listed in Table 4. Table 4: Oakridge Mall Planned Temporary Dewatering Wells

Well ID Address Status 119033 650 41st Street Not yet drilled 119034 650 41st Street Not yet drilled 119035 650 41st Street Not yet drilled 119036 650 41st Street Not yet drilled 119037 n/a Not yet drilled 119038 n/a Not yet drilled

3.2.2.2 Langara Golf Course Available records indicate that four wells were installed at Langara Golf Course circa August 1992. It is understood that water from these wells is used to irrigate the golf course. The subject wells were reported to be 15 cm (6 inch) diameter and advanced to depths of 23 to 98 metres (75 to 320 feet), with casing reported to be advanced to depths of 30 to 98 metres (100 to 320 feet). Information contained within the available logs is summarized in Table 3 below. Table 5: Langara Golf Course Well Records Summary

Bottom of Hole Date Date Well ID Location Site casing depth depth begun completed m (ft) m (ft)

74057 Langara SE Hole #4 26-Aug-92 29-Aug-92 98 (320) 98 (320)

74058 Langara NW Hole #3 26-Aug-92 29-Aug-92 - 23 (75)

74059 Langara NE Hole #2 24-Aug-92 25-Aug-92 30 (100) 37 (120)

74060 Langara SW Hole #1 22-Aug-92 24-Aug-92 68 (224) 74 (244)

3.3 Existing Boreholes Three boreholes were advanced by Horizon Engineering approximately 150 metres northwest of the subject site in 2017 for a separate project. The boreholes comprised solid stem auger with DCPT soundings and were advanced to depths of 30 metres. Soil conditions generally encountered at these auger holes generally comprised: • Concrete / Surficial Soil / Fill / Topsoil encountered from surface to depths of between approximately 0.3 and 2.1 metres below grade, underlain by • SILT to SANDY SILT (Capilano deposits) encountered from approximately 0.3 to 0.8 metres and 1.5 and 1.8 metres below grade, light brown to grey, some sand to sandy, sand is fine grained, soft to very stiff, underlain by • SILTY SAND to SILT (till-like / Vashon deposits) encountered from approximately 1.5 to 2.1 metres and 9.1 metres (bottom of auger holes) below grade, dark grey to grey, silt ranged from some sand to sandy, sand is fine grained, dense to very dense/very stiff to hard, soil is generally layered in zones of similar grain sizes as opposed to being mixed. DCPT effective refusal was encountered at depths of approximately 2.1 to 3.0 metres below grade. Perched groundwater seepage was encountered at depth of approximately 0.6 to 1.4 metres below grade during drilling. In May 2017, 4 weeks after piezometer installation, the groundwater level within the standpipe piezometer was measured to be at about 2.2 metres (7.2 feet) below grade; this was considered to be perched groundwater on the till-like soils. The moisture content testing carried out on samples of the till-like soils obtained at depths of about 4.0 and 7.0 metres below grade showed moisture content values in the order of 16 to 22%. The observed till-like soils were generally considered to have relatively low permeability and the permanent groundwater table was anticipated to be located below the investigated depths.

3.4 Existing Watercourses There are no known watercourses or historic streams within 25 metres of the site. The nearest 'historic' stream on record is indicated to be a tributary of Brewery Creek and is located approximately 0.5 km east of the site.

4.0 SUBSURFACE INVESTIGATION In order to characterize the subsurface soil conditions at the subject site, a subsurface investigation program comprising three solid stem auger test holes (AH20-1 to AH20-3) was completed on April 24, 2020. The test holes were advanced to depths ranging from 9.1 to 15.2 metres (30 to 50 feet) below existing site grades. Each of the augured test holes was accompanied by a Dynamic Cone Penetration Test (DCPT) sounding advanced from the ground surface until effective refusal, in order to characterize the relative density / consistency of the upper subsurface materials. In order to measure local surficial groundwater levels following the drilling, a standpipe piezometer was installed within one of the test holes with the ‘screen’ located at a location which is anticipated to coincide with the stratum containing the perched water table. The subsurface investigation was carried out using a truck mounted drill rig supplied and operated by Southland Drilling Co. The drilling was directed and the subsurface stratigraphy was logged by an engineer from our office. In order to reduce the risk of damaging existing, traceable, buried

utility lines, utility locate searches were conducted by Western Locates prior to our subsurface investigation. The approximate locations of the aforementioned test holes are shown on Figure 2 attached to this document. During drilling, disturbed grab samples were obtained from the solid stem auger flights which were returned to our laboratory for further analysis and classification.

4.1 Soil Conditions The soil stratigraphy encountered during the subsurface investigation is briefly described following. Please refer to the test hole logs in Appendix B for detailed information. 4.1.1 Fill / Topsoil At all test hole locations, a layer of topsoil / fill was encountered. The fill at the east side of the site was overlain by topsoil surfaced with lawn at the time of our investigation. The fill at the west side of the site was surfaced with asphalt. The fill was found to exist down to depths of approximately 0.3 to 0.9 metres (1.0 to 3.0 feet) below grade. 4.1.2 Organic Silt At all three test hole locations, the fill was underlain by a layer of dark brown, very soft to soft organic silt which contained trace fine grained sand and was moist. The organic silt was found to be 0.6 to 0.8 metres (2.0 to 2.5 feet) thick, extending to depths of 0.9 to 1.7 metres (3.0 to 5.5 feet) below existing site grades. 4.1.3 Sand to Silt / Sandy Silt to Silty Sand Beneath the organic silt was a stratum generally comprising fine-grained sand to silt, inferred to exist primarily in discrete lenses of similar grain sizes as opposed to being layered. This stratum was light brown to grey in colour and was loose to dense / firm to hard. This stratum was found to be 3.5 to 3.8 metres (11.5 to 12.5 feet) thick, extending to depths of 4.4 to 5.5 metres (14.5 to 18.0 feet) below existing site grades. 4.1.4 Sand (till-like) The above was underlain by grey, very dense, till-like deposits comprising grey, fine to medium grained sand with trace to no silt. Discrete lenses comprised primarily of silt were also encountered in this stratum. The moisture content of the sand was inferred to vary between moist to wet based on the drill cuttings returned. This stratum extended to the bottoms of the test holes.

4.2 Groundwater Conditions On June 2, 2020, the water level in the standpipe piezometer was found to be 1.6 metres (5.4 feet) below adjacent surface grades. This is anticipated to be a local perched aquifer and is within the development depth; thus, groundwater management will be required. Groundwater monitoring is ongoing within this piezometer and the results of this monitoring will be published in the final hydrogeological study.

4.3 Proposed Supplementary Investigation and Field Works In consideration of the requirements in the City of Vancouver Groundwater Management Bulletin, it is anticipated that supplementary field investigation, monitoring, and testing will be required to inform a final hydrogeological study, including quantifying the proximity of the excavation to any

aquifers, and providing estimates of groundwater flow which will be required to be managed during construction with these estimates supported by laboratory and/or field testing. These proposed works are detailed below. 4.3.1 Supplementary Field and Lab Works At the time of the original investigation, the requirements of the updated City of Vancouver Groundwater Management Bulletin were not in place. However, the Cambie Corridor Sewershed (to which the site belongs) has now been identified as an area requiring stringent groundwater analysis and management. It is therefore recommended that in order to fully meet these requirements, an additional investigation be carried out at the site to better characterize the depth to the Quadra Sands Aquifer underlying the site and the elevation of the permanent (not perched) water table. It is anticipated that mud rotary drilling methodology is best suited to the supplementary investigation, as this methodology is better able to manage artesian groundwater flows as may be expected to be encountered when penetrating the Quadra Sand aquifer beneath the site (in comparison with other drilling methodologies). We propose that one, mud rotary borehole be advanced to 20 to 25 metres (70 to 80 feet) below grade. Standard Penetration Tests (SPTs) would be advanced at select depths in the borehole to characterize subsurface conditions. A deep piezometer is proposed to be installed in the borehole to allow for groundwater monitoring. The proposed location of this borehole and piezometer are indicated in Figure 2 attached to the text of this report. Following the supplemental subsurface investigation, groundwater monitoring in the 'deep' piezometer would be carried out at select times throughout the year. Full-time groundwater monitoring is ongoing in the 'shallow' piezometer already installed on site. The results of groundwater monitoring will be provided in the final hydrogeological study. If required to inform the seepage analysis, a pump test may be carried out in one of the piezometers on site in order to allow quantitative estimation of the hydraulic conductivity of subsurface soils. Laboratory sieve analyses may also be carried out to inform this analysis.

5.0 GROUNDWATER MANAGEMENT PLAN This section outlines the proposed groundwater management plan during and post-construction. In general, it is considered that the subject site is suitable for the proposed development from a hydrogeological perspective provided that the following recommendations are implemented into the overall design and construction of the project.

5.1 Foundation Type Based on the soil and groundwater conditions encountered during the initial investigation and in order to satisfy the requirements of the City of Vancouver that groundwater (including perched) not be discharged into the municipal sewer following construction, it is envisaged that adoption of a 'tanked' underground parkade (and thus a raft slab) will be required. Infiltration is not considered to be practicable due to the relatively impermeable nature of the soils at the site and the high coverage of the proposed building over the property. It should be noted that, based on the subsurface soil conditions, were groundwater allowed to be intercepted by foundation drains and directed to the storm sewer, it is estimated that the actual

flows would be several orders of magnitude less than rainwater contributions. Actual estimates will be provided in our Final Hydrogeological Study following supplemental investigation and analyses.

5.2 Temporary Dewatering (During Construction) Temporary dewatering of the near-surface perched aquifer using conventional pumped sumps is anticipated to be required and feasible during construction to manage inflows due to perched groundwater and surface water runoff (i.e., due to precipitation events). It is envisaged that in order to manage buoyancy associated with hydrostatic pressures during construction of the building (i.e., before the full building weight is constructed), select temporary dewatering locations may be required to manage groundwater levels at the exterior of the site for a portion of construction. These dewatering locations could be installed congruent with excavation shoring at the site; a detailed plan in this regard will be incorporated into the design at a later date. Alternatively, foundation drains for the building may be installed and decommissioned following construction. Details regarding groundwater discharge and monitoring will be included in the final hydrogeological study and the Erosion and Sediment Control design for the site, both of which will be prepared by Horizon Engineering under separate cover and subject to City of Vancouver approval. This will include anticipated flow rates and treatment/discharge recommendations. Temporary dewatering is anticipated to be required for on the order of 12 to 24 months during construction at the subject site. Offsite Impacts?

5.3 Long-Term Dewatering (Following Construction) As noted, it is envisaged that adoption of a tanked underground parkade will be required. Thus, no permanent dewatering would be carried out at this site and impacts to the local groundwater regime are anticipated to be negligible. Slight elevation of the perched groundwater around the building may manifest. It is noted that based on the date of construction, the newly constructed buildings to the north and west of the subject site are inferred to utilise conventional perimeter drainage to manage perched groundwater. It is also understood that the proposed development to the south will utilise conventional perimeter drainage.

6.0 IMPACT ASSESSMENT A preliminary impact assessment of the proposed parkade construction and associated dewatering / tanking, including both temporary and permanent considerations, is discussed following. 6.1.1 Lowered Water Levels and Ground Subsidence Based on the anticipated local surficial geology, we do not envisage that significant settlement of soil strata at the adjacent neighbouring properties will occur due to groundwater discharge during construction. It is noted that the 0.6 to 0.8 metre-thick zone of organic silt may undergo minor consolidation settlement due to dewatering, but it is anticipated that this stratum has been removed from proximate (recently constructed) development sites which extend below the depth of this stratum. Minor settlement of proximate sidewalks / roadways may manifest if this surficial stratum was not removed during construction of these features; however, this is anticipated to be minor and not pose a safety risk provided that any tripping hazards that may develop during

construction are suitably addressed by the contractor. It is envisaged that repair / replacement of adjacent off-site landscaping is already anticipated. 6.1.2 Environmental There are no contaminants within or surrounding the site of which we have been made aware. Based on the subsurface geology underlying the site, it is not anticipated that the minor flow rates expected to be associated with temporary construction dewatering at this site will result in a significant risk of contamination migration; however, this should be confirmed by an environmental consultant. 6.1.3 Water Quality, Fish, Wildlife, Ecosystems Per available information in Section 3.2.1, the depth of excavation and dewatering will not extend (close to) the Quadra Sands Aquifer. Thus, no impact on groundwater quality or availability within this aquifer is anticipated at this time. Based on the subsurface investigation and relatively low permeability of subsurface soils, dewatering at the subject site is not anticipated to have wide-reaching impacts. Further, it is anticipated that flow volumes anticipated to be requiring pumping during construction will not be sufficient to impact watercourses, the closest of which is an historic stream (tributary of Brewery Creek 0.5 km east of the site). It is our opinion that conventional perimeter drainage pipes anticipated to be installed on neighbouring buildings with underground parkades (recently or soon-to be constructed, but permitted prior to the change in groundwater management requirements) may have already triggered any area-wide changes to the perched groundwater regime in the vicinity of the subject site. All groundwater pumped during construction will be treated by an ESC system so as to be suitable for discharge to downstream water bodies / habitats receiving stormwater discharge. 6.1.4 Artesian Per available information in Section 3.2.1, as the depth of excavation and dewatering will not extend (close) to the Quadra Sands Aquifer, artesian groundwater conditions are not anticipated to be a design or construction consideration. The supplementary investigation is designed to better characterize the elevation of the top of the Quadra Sands Aquifer underlying the site and the risks associated with artesian groundwater will be reviewed following the investigation. The drilling methodology has been selected to limit the risk of uncontrolled artesian groundwater during the investigation. 6.1.5 Flooding As the building is proposed to be designed as tanked, potential groundwater flooding is anticipated to be managed via building envelope and structural techniques. Potential flooding due to back-up of the municipal sanitary and/or storm sewers may be a risk and it is anticipated that the City of Vancouver would be able to provide insight as to sewer capacity and vulnerability to flooding. A backflow valve on the storm sewer connection would typically be recommended. The possibility of installation of a backflow valve on the sanitary sewer may be reviewed, if considered to be required. It is noted that, per the Vancouver Plumbing By-law Part 2, Article 2.4.6.4 backflow valves should be 'normally open'; this should be considered by the mechanical engineer, with consideration given to 'nominally inclined'. With respect to other sources of flooding, it is noted that the subject site is not located in the floodplain or in close proximity to any water bodies subject to flooding. Risks of flooding due to

pluvial events or fire extinguishment efforts are considered to be outside of the scope of this report. 6.1.6 Erosion The risk for excessive erosion at water bodies ultimately receiving the water from the excavation is considered to be negligible in consideration that groundwater volumes collected during construction will be minor compared to the rainwater contribution. This will be quantified in the final hydrogeological report.

6.2 Avoidance / Mitigation Measures Erosion and Sediment Control measures should be implemented to manage the sediment load potentially introduced by water pumped from the excavation. An environmental assessment may be required to evaluate other potential environmental implications of the subject construction dewatering.

7.0 REVIEW It is recommended that Horizon Engineering Inc. be provided with the opportunity to review Building Permit Application drawings from the architect, structural engineer, civil engineer, mechanical engineer, and landscape architect prior to Building Permit Application in order that the recommendations in this report can be confirmed or augmented, as required. Review/confirmation of the conclusions and recommendations provided herein should be carried out following supplemental investigation and receipt of any environmental assessments. In accordance with the 2019 Vancouver Building By-Law Letters of Assurance program, the Geotechnical Engineer must provide assurance that a geotechnical design will be prepared and that field reviews in support of the design assumptions will be performed. At this time, we envisage the following components will require hydrogeological design and field reviews: Geotechnical - Temporary 7.4 Temporary Construction Dewatering

It is the responsibility of the owner to ensure that Horizon Engineering is given the opportunity to carry out the aforementioned field reviews during construction. The 2019 VBBL Schedule C-B Letter of Assurance cannot be completed without having carried out the required field reviews. The owner is also advised that a Use Approval for construction-related dewatering must be received from the Province of BC prior to construction. Details regarding this application can be found at: https://portal.nrs.gov.bc.ca/web/client/-/use-approval-application

Consulting Geotechnical Engineers ©Horizon Engineering Inc.

Proposed Multi-Family Development Our File: 120-4724 5107-5119 Main Street & 196 East 35th Avenue, Vancouver, BC August 10, 2020 Preliminary Hydrogeological Study Appendices

Appendix A Figures

Consulting Geotechnical Engineers ©Horizon Engineering Inc. SITE LOCATION

1144690 BC Ltd c/o Bogner Development Group Ltd. SITE LOCATION PLAN Scale: File No: Date: FIGURE: PROPOSED RESIDENTIAL DEVELOPMENT NTS 120-4724 JUN/2020 5107-5119 Main Street & 196 East 35th Avenue Des: Dwn: Chk: Rev: 1 Vancouver, BC DM DM KS EAST 35TH AVENUE

33 m (110 ft)

196

PROP. BH/PZ

168 LANE 30 m (99 ft) 5107

AH20-2 MAIN STREET

5119 AH20-1 PZ20-1 AH20-3

LITTLE MOUNTAIN SITE

LEGEND: - Approximate location of Auger Hole

Reference: - Proposed location of future borehole City of Vancouver Orthophotos.

1144690 BC Ltd c/o Bogner Development Group Ltd. TEST HOLE LOCATION PLAN Scale: File No: Date: FIGURE: PROPOSED RESIDENTIAL DEVELOPMENT NTS 120-4724 JUN/2020 5107-5119 Main Street & 196 East 35th Avenue Des: Dwn: Chk: Rev: 2 Vancouver, BC DM DM KS Proposed Multi-Family Development Our File: 120-4724 5107-5119 Main Street & 196 East 35th Avenue, Vancouver, BC August 10, 2020 Preliminary Hydrogeological Study Appendices

Appendix B Test Hole Logs

Consulting Geotechnical Engineers ©Horizon Engineering Inc. Auger Hole Log No. AH20-1

LOGGED BY: DM REVIEWER: RN DATE: 2020 / 04 / 24 ADDRESS: 5107-5119 Main St & 196 E 35 Ave, Vancouver METHOD: Truck-mounted auger NORTHING: EASTING: ELEVATION: ±252.6' Type of Test: TYPE -- Type of sample Notes: Located in rear driveway of 5119 Main Street. Dynamic Cone Penetrometer Test (DCPT) SPT -- Split spoon Driller: Southland Becker Denseness Test (BDT) S -- Shelby tube Standard Penetration (SPT) G -- Grab Moisture Content (% of dry weight) O -- Other (specify) Plastic limit Liquid limit Ground water level

Depth SAMPLE Piezometer / Comments DESCRIPTION 20 40 60 80 / Additional Testing Depth DCPT TYPE m ft Symbol 0 0 ASPHALT 0.1 2 2 FILL (brown) 1 3 3 fine to coarse grained sand, moist, very loose G 1 2 2 101 1 ORGANIC SILT (dark brown) 3 9 9 trace fine sand, moist, very soft to soft G 2 12 12 24 5 SAND to SILT (light brown to grey) 8 8 measured fine grained sand, moist, loose to compact / 11 11 on 2 June 2 stiff to very stiff G 3 2020 - discrete localized zones of sand and silt 17 17 28 (slightly plastic) present, not mixed 16 16 SAND and SILT to SILTY SAND (grey) 9 39 39 3 10 fine to medium grained sand, trace rounded 43 43 drill hole to subrounded gravel, very stiff to hard / 31 31 open to 15' G 4 compact to dense, moist 27 27 at end of 16 drilling 4 38 38 G 5 93 93 SAND (TILL-LIKE) (grey) 14.5 16 15 fine to medium grained sand, trace to some 100 100 blows/8" 5 gravel, trace to no silt, inferred to contain occasional cobbles / boulders cuttings are wet - inferred to be moist DCPT cone 6 20 - inferred to be very dense stuck in drill - appears to be perched water at interface at 17.5'; G 6 limited 13 sample 7 return

8 sample is warm from G 7 drilling, limited 9 sample 30 - inferred to encounter increased cobbles not return recovered in samples below approximately 30 feet G 8 - inferred to be wet between approximately 10 driller infers 30-40 feet ground is 35 cobbly 11 G 9

12 40 minimal sample recovery 13 G 10

Auger Hole Terminated at 44.5' (effective 44.5 45 refusal) 14

15 50

LOGGED BY: DM REVIEWER: RN DATE: 2020 / 04 / 24 ADDRESS: 5107-5119 Main St & 196 E 35 Ave, Vancouver METHOD: Truck-mounted auger NORTHING: EASTING: ELEVATION: ±252.7' Type of Test: TYPE -- Type of sample Notes: Located in rear driveway of 5107 Main Street. Dynamic Cone Penetrometer Test (DCPT) SPT -- Split spoon Driller: Southland Becker Denseness Test (BDT) S -- Shelby tube Standard Penetration (SPT) G -- Grab Backfilled with drill cuttings and bentonite. Moisture Content (% of dry weight) O -- Other (specify) Plastic limit Liquid limit Ground water level

Depth SAMPLE Piezometer / Comments DESCRIPTION 20 40 60 80 / Additional Testing Depth DCPT TYPE m ft Symbol 0 0 ASPHALT 0.1 4 4 FILL (brown) 1 4 4 G 1 fine to coarse grained sand, moist, very loose 2 2 1 ORGANIC SILT (dark brown) 3 5 5 G 2 trace fine sand, moist, very soft to soft 12 12 5 SAND to SILT (grey) 9 9 fine grained sand, trace gravel, moist, 9 9 2 compact / stiff to very stiff G 3 10 10 - discrete localized zones of sand and silt 16 16 present, not mixed 15 15 3 10 15 15 18 18 G 4 27 27 4 57 57 100 100 SAND (TILL-LIKE) (grey) 14.5 15 fine to medium grained sand, trace to some 100 100 blows/7" 5 gravel, trace to no silt, inferred to G 5 contain occasional cobbles / boulders

- inferred to be moist 6 20 - inferred to be very dense - appears to be perched water at interface G 6

8 sample is warm from G 7 drilling, limited sample return

9 30

- silt lens at approximately 33 feet G 8 22 10

35 11 drill hole open to 36' G 9 at end of drilling

12 - inferred to be wet below approximately 40 40 feet cuttings are wet - inferred to encounter increased cobbles not G 10 recovered in samples below 13 approximately 43 feet driller infers ground is cobbly 45 14 G 11

15 50 Auger Hole Terminated at 50' (target depth) 50

LOGGED BY: DM REVIEWER: RN DATE: 2020 / 04 / 24 ADDRESS: 5107-5119 Main St & 196 E 35 Ave, Vancouver METHOD: Truck-mounted auger NORTHING: EASTING: ELEVATION: ±255.0' Type of Test: TYPE -- Type of sample Notes: Located in frony yard of 5119 Main Street. Dynamic Cone Penetrometer Test (DCPT) SPT -- Split spoon Driller: Southland Becker Denseness Test (BDT) S -- Shelby tube Standard Penetration (SPT) G -- Grab Backfilled with drill cuttings and bentonite. Moisture Content (% of dry weight) O -- Other (specify) Plastic limit Liquid limit Ground water level

Depth SAMPLE Piezometer / Comments DESCRIPTION 20 40 60 80 / Additional Testing Depth DCPT TYPE m ft Symbol 0 0 SOD 0.1 5 5 FILL (brown) 6 6 - initial DCPT fine to coarse grained sand, trace silt, moist, 24 24 attempt encountered loose to compact 3 10 10 residential water 1 service (repaired ORGANIC SILT (dark brown) 2 G 1 2 trace fine sand, moist, very soft to soft same-day) 5 7 7 SILT (light brown) 5.5 G 2 12 12 2 trace to some fine grained sand, moist, firm 7 18 18 to stiff G 3 SANDY SILT to SILTY SAND (grey) 17 17 fine grained sand, zones of medium grained 17 17 3 10 sand, trace gravel, moist, compact to 29 29 dense / very stiff to hard 13 13 G 4 16 16 - some brown mottling at top of layer G 5 4 16 16 - lense of compact fine grained sand at 11 feet 29 29 15 43 43 5 56 56 61 G 6 61 SAND (TILL-LIKE) (grey) 18 100 100 blows/4" fine grained sand, trace to some gravel, trace 6 20 to no silt, inferred to contain occasional cobbles / boulders G 7 - inferred to be moist sample is warm from 7 - inferred to be very dense drilling, limited sample return 25

8 G 8 drill hole open to 28' at end of drilling 9 30 Auger Hole Terminated at 30' (target depth) 30

35 11

12 40

45 14

15 50

PROJECT: FILE NO.: Proposed Multi-Family Development 120-4724 Bogner Development Group Ltd. CLIENT: SHEET 1 of 1 TESTHOLE LOG 120-4724 LOGS.GPJ HORIZON.GDT 11/6/20 HORIZON.GDT LOGS.GPJ 120-4724 LOG TESTHOLE Proposed Multi-Family Development Our File: 120-4724 5107-5119 Main Street & 196 East 35th Avenue, Vancouver, BC August 10, 2020 Preliminary Hydrogeological Study Appendices

Appendix C Submission Checklist for Hydrogeological Studies

Consulting Geotechnical Engineers ©Horizon Engineering Inc. Appendix A: Submission Checklist for Hydrogeological Studies

Below is a checklist for information that should be included in a submitted hydrogeological study (“the study”) 9. Sections 1, 2, 3, 4, 5, 6, and 8 apply to preliminary studies. Final (and revised final) studies also require the items listed in Section 7. If a submitted study is incomplete or illegible, authored by an unqualified individual, or does not contain sufficient analysis, the application may be deemed incomplete and returned to the applicant. Note that the checklist below is not exhaustive and City staff may occasionally request additional information as needed. In some situations, the requested information may even conflict with the requirements outlined in this bulletin, in which case the City’s request shall always prevail. This checklist is provided for convenience only and is not a substitute for applicable City by-laws or other regulations. It is the applicant's responsibility to ensure that any existing or proposed construction or other works complies with all applicable regulations, and that an appropriate level of site investigation and assessment is undertaken prior to submission.

1 Submission Format

 The hydrogeological study should be submitted as a separate document, rather than being combined with a geotechnical report, rainwater management plan, ESC plan, etc.

 The groundwater management plan, discharge and monitoring plan, and the impact assessment should be included within the hydrogeological study document.

 In addition to any hard copies requested by City staff, the study should be submitted electronically in a searchable (not scanned) PDF format with digitally embedded images of signature(s) and stamp(s).

 All pages of the study, including those in any appendices, should be numbered for easy reference by City staff.

 All diagrams, logs, and photos should be of sufficient resolution to interpret (i.e. not grainy or distorted), and any boreholes, wells or other labelled map features should be legible.

 All estimates should include a statement of assumptions.  All units should be metric.  All elevation and depth values (for the foundation, excavation, borehole, and water levels) should be reported in both geodetic elevation and metres below ground surface. Due to the potential variation in depth below ground surface for foundations and excavations, these values should be provided as a range (e.g. “2.1 – 5.3 metres below ground surface”) as well as in metres geodetic.

2 Submission Details

 Name of consulting company, names of author(s) and reviewer(s), and contact information  Date of submission  Title of submission  Type of submission (indicate one of the options below):  Preliminary hydrogeological study  Revised preliminary hydrogeological study

9 Note that this “Submission Checklist for Hydrogeological Studies” does not need to be filled out and submitted. It is intended as a guide for use by applicants and/or consultants.

City of Vancouver Page 12 Groundwater Management Bulletin April 2020  Final hydrogeological study  Revised final hydrogeological study  In a “Referenced Documents” section, list any separate supporting documents (e.g. geotechnical reports, shoring and excavation plans, architectural plans, environmental site assessments, etc.) that may contain relevant information and/or have been referred to in the hydrogeological study, and indicate whether these documents have already been submitted to the City.

3 Site Information

 Primary civic address, as well as the addresses of any related secondary parcels  Description of property boundary (i.e. bordering streets and properties)  Description of proposed development (e.g. multiple dwelling building, office building, etc.)  Description of existing and proposed buildings, and their locations on-site  Number of levels of below-ground structure (e.g. parking) in each building  Current site grade  Known or suspected contamination on or near site  Dimensions of entire property (metres2)  Dimensions of the excavation(s) (metres2)  Excavation elevation and depth (metres geodetic and metres below ground surface)  Foundation elevation and depth (metres geodetic and metres below ground surface)

4 Preliminary Hydrogeological Information

 In the hydrogeological study, discuss (e.g. in the Impact Assessment section) all that apply:  The site is located partly or wholly within one or more areas of concern for groundwater (see Figure 1 in Appendix C):

 Potential soil sensitivity to water table changes  Designated Floodplain  Potential flowing artesian conditions (Province of BC’s Well Drilling Advisory)  Sewershed within the Cambie Corridor  The proposed development is located anywhere in the city and includes an open-loop geoexchange system.

 The application (excluding single family homes, duplexes, and laneway homes) is being made directly at the development permit stage (i.e. under current zoning) within the Cambie Corridor study area.

 The site is subject to the Rezoning Policy for Sustainable Large Developments.  Any watercourses (including potential historic streams) within or near site (< 25 metres away)  Number of existing test pits on-site, as well as the number planned for site  Number of existing boreholes on-site, as well as the number planned for site  Description of soil conditions and properties of the underlying stratigraphy  The estimated proximity of the excavation to any aquifers, including perched aquifers  Number of existing wells on-site, as well as the number planned for site

City of Vancouver Page 13 Groundwater Management Bulletin April 2020  Address, Well Tag Number, and distance (in metres) of any wells (active or inactive) located within 1 km of site

 Any proposed works (e.g. additional well installation or monitoring) required to support completion of final hydrogeological study

 Any available hydrogeological data from nearby sites (e.g. from public well databases or previous projects completed by the applicant or consultant), such as lithology, water well record(s), date(s) of investigation, as well as proximity (in metres) to proposed development

5 Preliminary Groundwater Management

 A preliminary plan for any construction-related groundwater management, including details of the dewatering/drainage methods (e.g. cut-off walls, on-site storage, sump pumps, etc.), anticipated approximate duration of construction dewatering/drainage, pump location(s), discharge point(s), and any other relevant information. This plan should be included as part of the hydrogeological study. Note: groundwater includes water from perched aquifers

 A preliminary plan for permanent groundwater management, which should discuss any proposed dewatering/drainage methods such as impermeable boundaries (e.g. cut-off walls), waterproofed (e.g. tanked) foundations, reinjection or infiltration of groundwater, use of groundwater on-site (e.g. for non- potable water consumption), or other strategies to avoid groundwater discharge to the City’s sewer system. This plan should be included as part of the hydrogeological study. Note: groundwater includes water from perched aquifers

6 Impact Assessment The impact assessment should be included as part of the hydrogeological study, and discuss:

 Any significant risks or negative impacts (either on-site or off-site) that, based on the professional judgement of the study author, are reasonably likely to result from the development itself, or from the extraction/diversion of groundwater (including perched aquifers). These risks or impacts may include, but are not limited to:

 Lowered static water level(s) due to reduced recharge and/or increased groundwater extraction/diversion

 The potential for contaminant introduction and/or effects on known or suspected contaminants (e.g. migration of existing plumes)

 Reduced water quality and/or availability, including at nearby wells10 used for drinking, hydraulically connected streams or other surface water, or receiving water bodies

 Harm to fish, wildlife, or aquatic or terrestrial ecosystems  Encountering flowing artesian conditions and/or uncontrolled groundwater flow  Flooding (e.g. due to construction in areas with a high water table, sewer system capacity exceedances caused in part by dewatering and/or perimeter drains, seasonal variation in static water levels, etc.)

 Erosion (e.g. from the discharge of groundwater)  Ground subsidence (e.g. due to water level changes)  Potential damage to nearby property or infrastructure (e.g. due to dewatering)  Other potential concerns listed in Table 1 above, and/or specific to the site

10 See https://apps.nrs.gov.bc.ca/gwells/ or http://maps.gov.bc.ca/ess/hm/wrbc/ to find registered groundwater wells in BC.

City of Vancouver Page 14 Groundwater Management Bulletin April 2020  Proposed avoidance or mitigation measures for any identified significant risks or negative impacts

7 Specific Requirements for Final (or Revised Final) Hydrogeological Study

In addition to the above, the final study should also include:

 Updated content to reflect all material changes to the proposed development (e.g. confirmed number of levels of below-ground structure, confirmed excavation elevation and depth, etc.), as well as any new or refined supporting data, calculations, plans, reports or other materials obtained after submission of the preliminary study.

 An overview of the site investigation(s), including date(s), work completed, etc.  Borehole and/or well logs, including elevation(s) and depth(s) of stratigraphic changes, screen intervals and other observations (metres geodetic and metres below ground surface).

 Borehole and/or test pit maximum depth and minimum elevation (metres below ground surface and metres geodetic).

 Water level monitoring data (automated and/or manual measurements), including minimum level, maximum level, and average level measured over the entire monitoring period (provide a table listing quantified values in metres geodetic and metres below ground surface). Note: this data should also include any measured perched water levels.

 Date(s) and time(s) of water level measurements.  Measured or estimated range (in metres) in static water level(s) due to seasonal variation.  Hydraulic conductivity testing and analysis (e.g. slug tests).  A map of the site clearly showing the property boundary, surrounding sites, proposed building footprint(s), existing and proposed wells/test pits/boreholes, location(s) of groundwater extraction/diversion, and any other relevant information.

 Cross-section schematic(s) showing features such as: site stratigraphy; current site grade; location(s) and elevation(s)/depth(s) of planned excavation(s), foundation slab(s), test pits, boreholes, monitoring wells including screen intervals, static water level(s), seasonal range of water level(s) (measured or estimated, with dates shown if available); groundwater flow direction; and any proposed groundwater management solutions. See Figure 2 in Appendix C for an example.

 All final information related to groundwater management:  A finalized plan for construction-related groundwater management. See Section 5.  A discharge monitoring and reporting plan for any projects expected to have construction-related dewatering/drainage. This plan should include details of how flow will be measured, the type of flow meter being used, the measurement location(s), the frequency at which data is collected, who will be collecting the data, and any other relevant details. The plan should cover the entire dewatering/drainage period, and be included as part of the hydrogeological study.

 Estimated construction-related dewatering/drainage rate (litres/minute). Note: this should be a calculated estimate based on site-specific data, as terms such as “negligible” are not sufficient. Include calculations and the methodology used.

 A statement from the applicant to confirm that any water (i.e. groundwater or precipitation) discharged to the City’s sewer system during the construction dewatering period will be measured, and that the daily average flow rate measurements (or as requested by the City) will be submitted monthly to [email protected].

 A finalized plan for permanent groundwater management. See Section 5.

City of Vancouver Page 15 Groundwater Management Bulletin April 2020  If permanent (i.e. post-construction) dewatering/drainage is expected, indicate where this water is to be discharged (e.g. infiltration trench), and provide an explanation of how the groundwater management plan will avoid permanent groundwater discharges to the City’s sewer system.

 If any permanent discharge to the City’s sewer system is expected (e.g. from infrastructure such as foundation or perimeter drains), quantify the groundwater (i.e. excluding precipitation) flow rate in litres/minute. Note: this should be a calculated estimate based on site-specific data, as terms such as “negligible” are not sufficient. Include calculations and the methodology used.

 Any other information that could support the application, such as design drawings related to the groundwater management plan

 A statement from the applicant to confirm that the conditions in Section 2.2 of this bulletin will be met.  A finalized impact assessment. See Section 6.  Any test results or other information that could support the application, such as estimated aquifer flow direction, grain size analysis, soil density tests, groundwater velocity, graph(s) showing groundwater monitoring levels, etc.

 Finalized details of information included in any previous version(s) of the study.  Any other information needed to address the City’s feedback on previous version(s) of the study.  For sites subject to the Rezoning Policy for Sustainable Large Developments, applicants should refer to that policy for any additional requirements.

8 Other Requirements for All Hydrogeological Studies  The hydrogeological study should be prepared, signed, and sealed by a qualified professional (P.Eng. or P.Geo.) with competency in hydrogeology and registered with Engineers and Geoscientists British Columbia (EGBC).

 Discharge monitoring and reporting should be conducted by an individual who is registered with a professional organization that is governed by a code of ethics (e.g. CESCL, AScT, Engineer/Geoscientist, etc.).

 If after reviewing a hydrogeological study at any development stage, the City places conditions or holds and/or requests additional information, then a letter (e.g. Prior-To Response letter) should be provided that lists each of the City’s conditions and/or holds, and clearly explains how they have been addressed.

 The hydrogeological study should acknowledge that a Use Approval for construction-related dewatering must be received from the Province of BC prior to construction.

 If after submission of a final hydrogeological study, the applicant or consultant becomes aware of any changes that may be material to the City’s review of the study (e.g. if the proposed excavation depth increases), then the City should immediately be notified by emailing: [email protected].

 If any potentially serious issues related to groundwater are experienced at the site, such as excessive or uncontrolled flow, the applicant and/or consultant must immediately notify the City by calling 3-1-1.

City of Vancouver Page 16 Groundwater Management Bulletin April 2020