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HomeMy WebLinkAboutDosewallips Powerlines Reach Field Feasibility Memo_20220124 NATURAL SYSTEMS DESIGN 1 January 24, 2022 To: Tami Pokorny – Jefferson County Public Health Department From: Joey Smith, PE Torrey Luiting, PWS Date: January 24, 2022 Re: Dosewallips Powerlines Reach Preliminary Design - Field Feasibility Memo INTRODUCTION Natural Systems Design, Inc. (NSD), in partnership with Jefferson County and the Dosewallips Collaborative Group developed conceptual designs for restoration actions in the Powerlines Reach of Dosewallips as part of a previously completed RCO Planning and Assessment Project (#18-1228). As an outcome of the conceptual design and alternatives analysis conducted during the earlier Resiliency Plan phase of work, the Powerlines Reach was identified as the preferred location to further develop restoration designs aimed at re-establishing aquatic habitat complexity and providing spawning sites, as well as high- and low-water refugia for Chinook salmon and Hood Canal Summer Chum salmon, both ESA-threatened species. As part of furthering the development of preliminary restoration designs within the Powerlines Reach, NSD contracted with Jefferson County to perform a brief field feasibility study to assess potential construction access routes within publicly owned lands and evaluate the Engineered Log Jam (ELJ) structure types and locations proposed in the conceptual design. This memo presents the results of this feasibility study including initial considerations for construction access, ELJ design and construction method, and a preliminary determination of the potential Area of Potential Effect (APE) which will inform the scale and scope of additional field efforts, mainly cultural resources assessment and wetland delineation, needed to support preliminary design and permit applications. A key advantage to moving restoration designs forward within the Powerlines Reach is that the majority of the reach is publicly owned by a combination of Jefferson County, Washington State Parks, and Washington State Department of Natural Resources state-owned aquatic lands. With the exception of two landowners who own portions of the current active channel and left bank floodplain from RM 1 to RM 1.3, the entire reach is publicly owned (Figure 1). A drawback to restoration actions within the Powerlines Reach is that access to the reach for typical ELJ construction equipment (e.g., hydraulic excavators, log trucks, off road dump trucks) is very limited and requires establishment of lengthy access routes and coordination with local landowners and public agencies. Locating staging areas in proximity to the access routes and construction areas is similarly an important consideration. Determining preferred construction access routes, possible staging areas, and ELJ construction methods are key components of project design and may shape the scale and type of restoration actions feasible within the Powerlines reach. Consequently, access route and staging area location considerations were key aspects of our field feasibility efforts. JEFFERSON COUNTY PUBLIC HEALTH  DOSEWALLIPS POWERLINES REACH PRELIMINARY DESIGN NATURAL SYSTEMS DESIGN 2 January 24, 2022 Figure 1. Landownership in Dosewallips Powerlines Reach FIELD RECCONNIASSANCE On November 23, 2021, NSD and Jefferson County conducted a joint site visit to the Powerlines Reach to assess access conditions from the southern valley wall via a route that utilizes existing State Park fire roads, a private landowner’s driveway, and the BPA transmission line easement. Representatives from NSD included Torrey Luiting, Project Manager and Ecologist and Joey Smith, Project Engineer. Representatives from Jefferson County included Tami Pokorny, Project Manager, and John Gussman, drone operator. Goals of the field feasibility site visit were to assess the existing access route from the southern valley wall (right bank), collect drone aerial imagery of the reach, and qualitatively evaluate potential staging areas, ecological considerations (e.g., sensitive resources such as large trees and potential wetlands), and conceptual ELJ types and locations. The field team successfully utilized a combination of fire roads, a private driveway, unimproved roads beneath the BPA transmission lines and a decommissioned logging road (orange dashed route shown in Figure 2) to reach the right bank at approximately RM 1.5 within the Powerlines Reach. The total length of this access route was approximately 1.5 miles and involved passing through three locked gates, two of which were on State Parks lands and the third gate located at the entrance to the private landowner’s parcel. Figure 2 also shows the location and orientation of photographs taken during the field reconnaissance illustrating the condition of site access at a variety of locations. JEFFERSON COUNTY PUBLIC HEALTH  DOSEWALLIPS POWERLINES REACH PRELIMINARY DESIGN NATURAL SYSTEMS DESIGN 3 January 24, 2022 Figure 2 Access route from south via state parks and transmission line easement Access through State Parks land consisted of a single-lane, gravel-surfaced fire road that was traversable via passenger vehicles. Along this section of the access route were two gates that required coordination with State Parks to unlock and facilitate access. Several hiking trails crossed this fire road, and visitors to the park were observed crossing the fire road to access these trails. Additionally, this section of the route contained numerous stream/drainage course crossings which consisted of small culverts. Following the second gate on the State Park fire road, the access route crosses a private landowner’s property which contains a small, locked gate that required coordination with the landowner to facilitate access. Another larger stream crossing was located within the access route in this private parcel. Past the private landowner’s driveway, the access road entered the Bonneville Power Administration (BPA) transmission line easement. Beneath the transmission lines, the access route becomes an unimproved dirt double-track that would likely require a high-clearance 4-wheel drive vehicle to navigate (Photo A). Within the transmission line easement, two parallel transmission lines were present, a taller and presumably higher voltage line and a shorter line. Based on the transmission line tower types, the vertical distance to the transmission lines is estimated at approximately 60 feet. At least two portions of the easement displayed surface JEFFERSON COUNTY PUBLIC HEALTH  DOSEWALLIPS POWERLINES REACH PRELIMINARY DESIGN NATURAL SYSTEMS DESIGN 4 January 24, 2022 ponding/drainage at the time of our site visit, which may be indicative of potential sensitive resources (e.g., wetlands). Access beneath the transmission lines continued for approximately 1,000 feet to the northeast. Photo A. Dirt double-track under BPA transmission lines. From the BPA transmission line easement, the access route dropped down the valley following an abandoned logging road to the west. This road had not been formally decommissioned and would be feasible to utilize as an access route with minor improvements, such as clearing of logs and other debris, and potential gravel surfacing (Photo B). A single 14-inch corrugated plastic pipe is present where a small drainage crossed the access route. The area adjacent to the road surrounding the drainage may support associated wetlands. The abandoned logging road descended for approximately 1,000 feet before ending at a small tributary to the Dosewallips named Trainwreck Creek and its associated floodplain bench (Photo C). Access to the river required crossing the approximately 15-foot-wide creek channel and traversing a floodplain terrace above the right bank of the Dosewallips River. The right bank floodplain terrace is located on an approximately 6-foot-tall cut bank and is vegetated with predominately native trees, shrubs, and herbaceous species, some of which are indicative of potential wetland conditions. Three large, mature trees, an approximately 48-inch diameter at breast height (dbh) bigleaf maple (Acer macrophyllum), and an approximately 48-inch dbh double trunked western red cedar (Thuja plicata), and a similar diameter conifer are present in this area, with remaining vegetation consisting of smaller red alder (Alnus rubra) trees and a mixture of native shrubs. JEFFERSON COUNTY PUBLIC HEALTH  DOSEWALLIPS POWERLINES REACH PRELIMINARY DESIGN NATURAL SYSTEMS DESIGN 5 January 24, 2022 Photo B. Abandoned logging road descending from transmission line easement toward Dosewallips River. Photo C. Trainwreck Creek and adjacent floodplain at the terminus of the abandoned logging road. JEFFERSON COUNTY PUBLIC HEALTH  DOSEWALLIPS POWERLINES REACH PRELIMINARY DESIGN NATURAL SYSTEMS DESIGN 6 January 24, 2022 The 1.5-mile access route from Dosewallips State Park ends on the right bank of the Dosewallips river near RM 1.5, near the middle of the Powerlines Reach. Across the river, a gravel bar is located along the left bank (Photo D) which would provide construction access upstream and downstream once a crossing over the active channel was established. Photo D. View across Dosewallips River toward left bank gravel bar from right bank floodplain bench. ELJ DESIGN AND CONSTRUCTION METHOD CONSIDERATIONS Ground-based ELJ Considerations The conceptual design of restoration actions within the Powerlines Reach included placement of large ELJ structures within the active channel and smaller structures within existing side channels. The design and construction of large ELJ structures within an active river environment requires the application of hydraulic and civil engineering principals to support project design and the mobilization of heavy construction equipment and construction techniques to successfully implement the project. In the case of the Dosewallips Powerlines Reach, the conceptual design calls for large Apex and Deflector type ELJs to be installed in the main active channel. These structures would resist the hydraulic forces during large flood events from embedded rootwad posts or driven timber piles that extend into the channel bed below the structure. An example of a typical Apex and deflector type ELJ structures supported by rootwad posts is shown in Figure 3. JEFFERSON COUNTY PUBLIC HEALTH  DOSEWALLIPS POWERLINES REACH PRELIMINARY DESIGN NATURAL SYSTEMS DESIGN 7 January 24, 2022 Figure 3. Example of Post-Supported ELJs on the Cispus River (NSD 2021) The construction of structures of this magnitude and type utilizes heavy civil construction equipment, including tracked hydraulic excavators, off-road haul trucks, logging trucks, and associated support vehicles such as refueling trucks and work trucks. Our feasibility assessment results indicate it is feasible to mobilize this type of equipment to the Powerlines Reach work area through the access route described above. However, it would require coordination with State Parks and private landowners along the route, clearing of native vegetation to establish staging areas and turn- arounds, constructing temporary bridges, and potential placement of gravel surfacing to improve the roadway surface. Following construction, the portions of the access route beyond the BPA transmission line easement could be formally decommissioned and restored. Along the remainder of the access road, the route would likely need to be restored to its pre-construction conditions or otherwise improved based upon agreements made with State Parks and the private landowner, and potentially also with BPA. Helicopter-placed ELJ Considerations An alternative method for designing and constructing ELJ structures in locations where construction access is difficult is to “fly in” ELJ structures via heavy-lift helicopters and place them with the support of a limited ground crew. Helicopter-placed ELJ structures are ballasted by large boulder pairs which are secured by chain or cable and laid over the main structural members of the ELJ, rather than rootwad posts or timber piles embedded beneath the channel bed. An example of a helicopter placed ELJ is shown in Figure 4. An advantage to helicopter placed structures is that limited ground support, consisting only of a team on foot to unhook logs from the helicopter delivery line, is needed within the active work area. This greatly reduces or eliminates the need to make roadway improvements to bring heavy construction equipment into the work area. Apex ELJs Deflector ELJ JEFFERSON COUNTY PUBLIC HEALTH  DOSEWALLIPS POWERLINES REACH PRELIMINARY DESIGN NATURAL SYSTEMS DESIGN 8 January 24, 2022 Figure 4. Example of helicopter-placed ELJ in the Upper Dungeness River (NSD 2021). Helicopter-placed ELJ structures are typically placed in lower risk areas where the consequences of structure movement or failure is low and there is tolerance for structures adjusting over time. If helicopter placement is being considered, risks to both public safety and property damage are assessed part of preliminary project design, following the guidelines developed in the Large Woody Material – Risk Based Design Guidelines developed by the US. Bureau of Reclamation (Knuston and Fealko, 2014). This process evaluates both the reach characteristics and proposed ELJ structure design and recommends both a design flow for evaluating structure stability and a minimum factor of safety for ELJ structures to meet. CONSTRUCTION ACCESS ALTERNATIVES Ground-based Construction Access Construction access along the 1.5-mile route starting at the Dosewallips State Park could provide a feasible means to access the Powerlines Reach for implementing potential restoration actions that require ground-based machinery, including large ELJ structures, smaller side channel and habitat-scale structures, and riparian/floodplain vegetation management and enhancement (e.g., conifer underplanting). The length and nature of the 1.5-mile, single lane, access route will reduce the efficiency of delivery of construction materials, particularly logs required for the ELJs, and mobilization of heavy civil construction equipment. This will increase costs for delivering logs and construction mobilization compared to an equivalently sized project with direct access along public roadways. This potential access route through the Dosewallips State Park has drawbacks, primarily the overall length of the route and the variety of landowners that this route traverses. Within the State Park lands, the access route is generally in good condition, consisting of a single-lane gravel surfaced roadway and would likely be feasible to mobilize heavy equipment (e.g., tractor-trailers, dump trucks, logging trucks, etc.) with minimal roadway improvements. However, there are limited turn-offs along this route, areas immediately adjacent to the road may support wetlands, and its location within a State Park means that coordination with the park management FLOW JEFFERSON COUNTY PUBLIC HEALTH  DOSEWALLIPS POWERLINES REACH PRELIMINARY DESIGN NATURAL SYSTEMS DESIGN 9 January 24, 2022 and considerations of limiting public access to the existing trail network during construction would need to be advanced during preliminary design. Within the private landowner’s parcel, the roadway is in a similar condition to the State Parks road and would also be feasible to mobilize heavy equipment without major roadway improvements. Coordination with the landowner would be required to ensure safe access to their residence if this were to be utilized as the construction access route. Within the BPA transmission line easement, the roadway is still in generally good condition, although sees much less use and does not have contiguous gravel surfacing. It is possible that roadway improvements, primarily gravel surfacing, may be needed to utilize this portion of the access route. Past the BPA transmission line easement, the access route to the Dosewallips River continues along an abandoned logging road. This roadway is also still in fairly good condition, but clearing of fallen trees and other debris, as well as potential gravel surfacing may be needed to facilitate construction access. At the terminus of the abandoned logging road, a small crossing over Trainwreck Creek would need to be established and then a new access road and small staging area established within the right bank terrace of the Dosewallips River. A temporary crossing would have impacts to the stream bed, banks, and adjacent floodplain vegetation (including potential wetlands) which would need to be restored as part of the project construction. From this location, a temporary bridge spanning the Dosewallips River would need to be established to provide access to the left bank gravel bar. At this location the active channel is approximately 120 feet wide. The means and methods of establishing this crossing would be the ultimately be determined by the construction contractor, but feasible options include temporary railcar bridges supported on ecology block footings or timber stringers. An example of a multi-span railcar temporary bridge for similar span river crossings is shown in Figure 5. Once access is established to the left bank gravel bar, construction access upstream and downstream within the project area would be along the unvegetated portions of the gravel bar would be straightforward and would require minimal roadway improvements or clearing of native vegetation. Figure 5. Example of multi-span railcar bridge used as temporary channel crossing. JEFFERSON COUNTY PUBLIC HEALTH  DOSEWALLIPS POWERLINES REACH PRELIMINARY DESIGN NATURAL SYSTEMS DESIGN 10 January 24, 2022 Helicopter Construction Access For helicopter-placed ELJ structures, ELJ elements are flown in via a heavy-lift helicopter and placed with the aid of a ground crew in the active worksite. ELJ elements, including large logs, boulder pairs, and racking bundles, are flown in sequentially by the helicopter and uncoupled from the delivery line by the ground-based work crew. An example of a heavy-lift helicopter transporting a large log with rootwad to a partially completed ELJ is shown in Figure 6. Figure 6. Heavy-lift helicopter flying in single log for ELJ placement on upper Dungeness River. A helicopter-placed ELJ construction approach does not require the establishment of a staging or materials delivery area within the active work site and the required access for the work area is limited to a foot-based ground crew who uncouples the materials from the helicopter delivery line. This approach does require the establishment of a staging area located within a short flight path from the work area. This staging area serves as the delivery location for ELJ materials (logs and boulders) and as a refueling location for the helicopter. Typically, old borrow pits or other cleared areas with roadway access within timber lands provide feasible locations. An additional consideration is that loaded helicopters are typically required to maintain a minimum 400-foot buffer from any home or public infrastructure, such as the BPA transmission line that bisects the Powerlines Reach. Our initial correspondence with heavy-lift helicopter contractors indicates that the upper Powerlines Reach would be a feasible area to install helicopter-placed ELJs and that potentially suitable staging areas may be located within the timber lands to the southwest. Landowner coordination and approval would of course be required. A conceptual work area for helicopter-placed ELJs and the approximate buffers from private homes and the BPA transmission lines are illustrated in Figure 7. JEFFERSON COUNTY PUBLIC HEALTH  DOSEWALLIPS POWERLINES REACH PRELIMINARY DESIGN NATURAL SYSTEMS DESIGN 11 January 24, 2022 Figure 7. Conceptual work area for helicopter-placed ELJs and approximate buffers AREA OF POTENTIAL EFFECT AND PERMITTING CONSIDERATIONS Following the completion of the preliminary design, project construction permits will need to be acquired to ensure that federal, state, and local regulatory conditions are established prior to finalizing project design and proceeding to advertisement, bids, and construction. As part of this process, the Area of Potential Effect (APE) for the project will need to be established to ensure the extent and nature of sensitive resources (e.g., wetlands, cultural resources, etc.) are known and that the project avoids, minimizes, and anticipates restoration of unavoidable temporary impacts in the design and permit application materials. The APE needs to encompass not only the active work area where ELJ structures and other restoration elements are being constructed (e.g., any areas of excavation and areas of floodplain planting), but also the access, staging and temporary water crossings needed to facilitate mobilizing equipment to the work area and moving through the work area. A ground-based approach with heavy civil equipment will necessitate a larger project APE that effectively encompasses site access, staging areas, log delivery locations, equipment refueling, and any other construction actions taken, as well as any areas of floodplain grading and planting. A helicopter-based approach would limit the project APE to the active work area within the river channel and any areas of floodplain grading and planting, plus the helicopter staging/takeoff location, ideally located in within existing cleared areas in the adjacent timber lands. JEFFERSON COUNTY PUBLIC HEALTH  DOSEWALLIPS POWERLINES REACH PRELIMINARY DESIGN NATURAL SYSTEMS DESIGN 12 January 24, 2022 CONCLUSIONS This field feasibility assessment supports the conclusion that there is a viable, ground-based construction access route beginning in Dosewallips State Park and extending through a private landowner’s parcel and the BPA transmission line easement and extending to the vicinity of Trainwreck Creek. This route offers a feasible approach to mobilize ground-based heavy civil equipment to construct the types and scale of restoration elements proposed in the conceptual design for the Dosewallips Powerlines Reach. However, outreach early in the preliminary design process to State Parks and the private landowner is critically important to determine their willingness to support construction access through their lands. Such outreach also needs to occur early in the preliminary design process so that the extent of the potential APE can be drafted, and cultural and wetlands work completed within it to identify any sensitive resources. Our initial desktop feasibility analysis and correspondence with heavy-lift helicopter contractors indicates that portions of the Powerlines Reach also offer a feasible area to place to install ELJ structures designed for helicopter placement. Additional outreach with the Dosewallips Collaborative Group and other project stakeholders needs to be conducted to assess the desirability of pursing helicopter-placed ELJs for the upper Powerlines Reach as part of the preliminary design process. Based on the outcome of the field feasibility effort, we recommend that initial steps in the preliminary design process include specific outreach to inform a decision on site access method because that decision affects ELJ structure design and the extent of the project’s APE and sensitive resources surveys. Specifically, we recommend:  Outreach and consultation with Dosewallips State Park representatives, the private landowner, and BPA to determine willingness to support construction access through their lands and determine key design constraints associated with ground-based site access.  Outreach and consultation with the Dosewallips Collaborative group to determine if helicopter-placed ELJ structures can meet the restoration objectives and to determine if this design and construction approach should be advanced in preliminary design instead of ELJs designed for ground-based construction access.  Conduct preliminary risk assessment for the project reach to inform the design of either helicopter- placed or ground-based ELJ structures. The outcome of the risk assessment will help inform the stability analysis of any ELJs proposed for the reach and would help the design team determine if the Powerlines Reach is a suitable location for helicopter-placed ELJ structures.