September 11, 2013 12:30 pm to 5:15 pm DUHAMEL: Informal tour with Greg Utzig, Martin Carver, Doug Thorburn, Tyler Hodgkinson, Rob, Kim Green and Will Halleran. General Findings from the Field Review – Nadine Podmoroff 1) Information and Observations Landslides Most of the road and cutblocks are low to moderate landslide risk. The area immediately upslope and north of where the spur road crosses the gully is high risk. There was likely a small landslide there in the past (likely more than 250 years ago). The landslide area is still not fully regenerated. The area near the former headscarp and immediately to the north appeared to have minor soil creep. The slide probably occurred after a fire; the roots rotted and then it rained. It is possible that the road cut will reactivate this slide area. If a slide occurs here, it will likely be small, and may be contained by the road, but it may also continue down the gully. If it enters the gully, it may reach Duhamel Creek, depending on its size. The road and culvert to cross the gully and creek will be constructed early October. Hydrology and Flooding Potential This project site appears to be typical for Duhamel Creek drainage - shallow and coarse textured soils - so water runs off quickly (called: ” flashiness”). This leads to flooding on the fan after major precipitation events, rapid snowmelt, or rain-on-snow. Constructing roads will likely increase flashiness, but the present amount of roads in the drainage is likely too small to have a measurable effect. As more roads are built in the future this may change. Doug indicated that the Equivalent Clearcut Area of Duhamel Creek is at 15-16% with the development, though he has not provided documentation of how this was determined. As Kalesnikoff continues to harvest this will increase. As ECA increases, and as road density increases, the likelihood also goes up that Duhamel’s peak flow will increase. Kalesnikoff’s hydrology assessment is based on stationary climates and does not take into account climate change which includes non-stationary hydrological data and assessments. Extreme weather events such as the major storm that hit north Kootenay Lake recently will likely increase in frequency and intensity in the coming years, and therefore the past level of risk is not a great predictor of future risk. There appear to be some unusual and un-explained anomalies in flow and sediment transport in the main tributary valley entering Duhamel Creek from the West. There may be some relationship between flow in that tributary and the creek in the gully in the development. These do not affect the potential impacts from the development, but may be something for further study to understand the flow regime of Duhamel Creek in general. History of Large flood events: 1948, 1956 and 1974 Kim Green did not walk the entire Creek. She drove the main road and did forays down to the creek, on her own, walking creek sections of unspecified length. Sediment Sources and Sediment Transport The soils along the road are generally sandy and shallow, except in the lower portion where they are very sandy and deep. In some areas there is moisture seeping in the soils and over underlying bedrock. The sandy soils are extremely erodible during high intensity storms and during snowmelt. The dry sandy cutbanks are actively raveling into the ditch, and in some cases the cutbanks are starting to slough due to wetness. Kalesnikoff is installing sediment traps to try to capture the sediment, but they will require continuous maintenance to keep sediment from reaching Duhamel Creek. If they are not cleaned out, it can create an even bigger problem if it plugs up; fills up and/or breaks. The traps are not very large, and may fill up after one rainfall given the erodibility of the sandy soils. Including the ditch, the road needs to be 4.5 meters wide here. Rob said it is 4 meters wide and “that’s all we need”. Duhamel Creek itself has a number of low gradient areas between the harvesting area and the fan, and these will likely trap a major portion of the sediment produced by the development. This settling out may negatively impact wetland values in the low gradient areas, while sharply reducing the likelihood of direct impact to the fan and residences on the fan. 2) Interpretations There will be material which will go into the creek. Duhamel Creek sediment load is already high and mostly consist of sand. There is already a great deal of sand in the creek. We will need to monitor this creek and sediment build up in case it gets worse. Water quality may be problematic rather than safety of lives and homes. There are no “RED Lights” found during the tour. If we hire private GEO techs we will likely waste our money. These are somewhat risky things, but these risks are generally considered acceptable in forest harvesting and road construction in BC. The creek is not going to plug up as a result of this logging and road building. There is unlikely to be a significant change due to this development alone in the likelihood of the creek plugging up. It would have to be a very large slide to cause the creek to plug up, and this is unlikely to occur from this development (unlikely, but not impossible). This is a cumulative effects problem. Sediment traps may fill after first rain storm. The sandy face will erode. It will fill up the trap with sandy sediment. At the top of this steep sandy area, a break in the road grade was suggested to Rob to ensure water does not run down the road into the steep sandy area. We need to monitor the sandy corner because sand erosion can be problematic here. Except in the area of the gully, there is minimal risk of Landslides. Slope Stability The risk of major landslide is low except in and immediately past the gully where it is high. “Low risk” when assessing landslide risk, commonly includes areas which can still include a significant probability of sliding – in some cases up to approximately 30%. Below the gully sediment will reach the creek to some degree, but it is unlikely to block the creek. Kim Green thinks that the wetland fan will capture any potential landslide debris. States that logging companies need to do hydro geomorphic assessments on alluvial fans below logging projects to assess risks to fans. She feels that the potential for flooding on the fan is the major concern, and that this logging and road building will not affect that. We are not going to stop Kalesnikoff Lumber in a legal way unless a professional states in his report, “This project WILL cause a landslide and WILL affect safety”, and even this will most probably not work. The Govt. has given Kalesnikoff Lumber permission to log a great deal in the 6 mile area. In addition, Kalesnikoff in conjunction with the Interior Lumber Manufacturers Association has been lobbying the Provincial Govt., the RDCK and the City of Nelson in an attempt to reduce legislation/laws so they can log even more with fewer restrictions. 3) Suggestions to the Community from Greg and Martin We need to establish the best prescription possible; which include protocols of safe road construction, harvesting and maintenance practices with Kalesnikoff Lumber. We need to request annual joint field assessments with Kalesnikoff Lumber. The community needs to monitor road construction and maintenance. We need to monitor roads, culverts and ditches during rainy days. We need to take pictures and email these to Tyler when problems arise, and request they attend to mitigation and maintenance. We will need to call Kalesnikoff to mitigate problems as they arise (culverts plugged, ditches filled etc.) We will need to re-evaluate and monitor cumulative effects as more road construction and logging occurs in the 6 mile area. We will need to meet with Kalesnikoff’s annually to go over all recent assessments and harvesting plans. What our community is going through is something many communities are experiencing at this time, due to the weakened legislation and recent upsurge in logging due to increased lumber prices. Logging companies are going to continue to log in our watersheds, so the actions we take now may help us as a community to create a long term plan which will mitigate impacts and this may enable other communities to also positively act on behalf of their watersheds. This long-term planning should consider cumulative impacts and the potential for increased road construction and logging to eventually reach levels that will increase flooding risk on the fan. We are for the most part at the mercy of the Logging Company. Even if we hire a line of professionals to assess this project, if something happens, we will have spent a lot of money, have a line of professional opinions, and we still may have a weak case (Laird Creek is a recent example). Kalesnikoff who has the license to harvest here is basically in charge, so we need to work with them to plan future activities in the watershed. As the Forest Practices Board says in its report, the Province is unwilling to step in.
Posted on: Wed, 30 Oct 2013 17:01:41 +0000
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