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Engineering and Geotechnical Challenges

Updated: Aug 2, 2023

The proposed development at 1050 Spiller Road represents a significant shift in land use for the property and comes with significant and widespread potential impacts. Yet there has apparently been minimal technical analysis done by Canadian Horizons to support their plans. Instead, they rely on outdated studies from the 2014 OCP which was repealed as part of the adoption of the 2019-2045 OCP. Moreover, Issues arising subsequent to the 2014 OCP, including the Outlook and Kettle Ridge developments on the Naramata Bench and other high-density developments in Kelowna, have all been ignored despite the geology being very similar to the proposed Spiller Road site.

The geology of the Spiller Road property is complex with a considerable number of bedrock outcrops, near-surface outcrops and glacial and post glacial sediments in between. These conditions are very difficult and challenging and require considerable blasting and destruction of the landscape in order to build. Blasting may also potentially open subterranean aquifers or reveal ground conditions that make construction of drainage systems, building foundations, roads and other infrastructure difficult and expensive.

In a high-density housing development, the addition of asphalt and concrete compounded by steep grades, will significantly alter drainage courses, and removal and alteration of ground cover will reduce water infiltration thereby increasing the likelihood of flooding and erosion.

There is a distinct likelihood of legal ramifications for the City of Penticton if the developer’s drainage system fails. Several lawsuits are pending in the case of the Outlook and Kettle Ridge Benchlands high-density developments on the Naramata Bench where approved drainage designs were ineffective and caused severe damage to downhill properties.

In these cases, the Province was the approving authority and is being sued. Since the geology in these areas is similar to that of the Spiller Road development, a similar drainage disaster can be anticipated if the Spiller Road development proceeds. If so, the City of Penticton, as the approving authority, would be involved as a defendant to a very expensive lawsuit, and ultimately, it falls to the taxpayer to fund any settlement.

The lesson learned from the Outlook and Kettle Ridge Benchlands case is that, by reason of its unique geology, the upland hills to the east of Okanagan Lake are not suitable for urban development. The City, as the authority responsible for zoning, cannot in good faith ignore the fact that, if developed, excess runoff and flooding from the Spiller Road site will inevitably pose a serious safety risk to the surrounding area.

The Naramata Bench has a complex geological history. The geology includes igneous, metamorphic and sedimentary deposits resulting in features that characterize this unique area. Throughout the Pleistocene era (2.6 million-11,000 years ago) the area was repeatedly covered by the Cordilleran ice sheet. This ice reached as much as 3,000 meters in thickness and the weight caused scouring of the underlying accumulation areas. Glacial retreat was characterized by “downmelting"within the uplands area first and subsequently in the valley. The Naramata Bench encompasses a series of silt benches formed as glacial Lake Penticton receded at the end of the last glacial period. This makes the Naramata Bench unique in the world by producing wine grown from glacial sediments.

The resultant landforms along the edges and base of the valley include alluvial fans, associated gullies and stream channels. The sediment types associated with these landforms include lacustrine silt and clay, mixed deposits of glacial and post glacial sediments of till, clay silty sand, sand and gravel and outcrops of coarse-grained metamorphic rocks. The bedrock underlying these sediments consists predominantly of layered gneiss. The ravine area contains fragment bedrock/boulders with slopes that are steep and heavily fractured.

The landscape elements specifically on the CH Development property and adjacent properties have a moderate to steep western aspect slope with mixed deposits glacial sediment and outcrops of coarse grained metamorphic rocks.

The Canadian Horizons (CH) draft development plan on the 1050 Spiller Road public engagement website was only available from May 25th to June 15, 2020. Two notification signs with erected May 25, one at the 880 Naramata Road property, and the other posted on the 1050 Spiller Road property. These signs were also removed on June 15th. This draft development plan on CH’s website lacked any specific geotechnical detail. The City of Penticton was contacted through a Freedom of Information request and In a conversation with the City’s Development Infrastructure Manager, it was confirmed that limited geotechnical investigation has been done by CH to that point. The city indicated the developer would be required to undertake a full and detailed investigation prior to subdivision approval. However, subdivision approval would be subsequent to the current rezoning application before council. This would prejudice the rights of residents to be fully informed prior to approval of any rezoning application, and make the development much more difficult to stop.

The City of Penticton’s OCP 2045 Section 4.4.1 Resilience to Natural Hazards-states: “Ensure that Penticton is proactive in anticipating and preparing for increasing risks, exposure and cast associated with wildfire, flooding and geotechnical hazards resulting from a changing climate”

The Spiller Road/ Reservoir Road Area Neighborhood Concept Plan (NCP) February 2014 was repealed with the adoption of the 2045 OCP. Nevertheless, in the appendices, it included several excellent studies and technical analysis of the area stretching North to the Three Blind Mice trails as it is anticipated that the Spiller Road property would only be the first phase of numerous additional building phases. These studies make consistent reference to the steep terrain and the presence of bedrock outcrops which would be difficult and costly to develop as they would require blasting in order to remove and level the terrain in order to develop the land. reference is also made to the thin nature of the soil overburden "which will likely be a key contributor to water management issues" [See also Stormwater Issues could lead to legal battles]

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