Rocky Mountain Field Institute

Transcription

1 Rocky Mountain Field Institute Palmer Park Stewardship Project 2016 Annual Project Report December 20, 2016 Report prepared by: Andy Riter, Program Coordinator and Alex Hladkyj, Field Instructor 815 South 25 th Street, Suite 101 Colorado Springs, CO Dedicated to the conservation and stewardship of public lands in Southern Colorado

2 Rocky Mountain Field Institute 2 SUMMARY The 2016 field season marked the first in which the Rocky Mountain Field Institute (RMFI) conducted stewardship projects in Palmer Park, one of several properties owned and managed by the City of Colorado Springs Parks, Recreation, and Cultural Services Department (PRCS). The stewardship work was completed in close partnership with PRCS staff and with the local park Friends group, the Guardians of Palmer Park (GoPP). The project was funded by the PRCS. From April through June, RMFI led work in 2 primary areas of the park, which included a segment of the Palmer Point Trail located on the park s northwest periphery, and on segments of the historic Edna Mae Bennett Nature Trail, also located in the northwest of the park (Appendix A). The objectives for work on the Palmer Point Trail included making improvements to a section of unsustainable trail that was creating drainage and sediment issues in an adjoining neighborhood. Along the Edna Mae Trail, the overall objectives were to stabilize damaged and incised segments of the trail where it was paved by historic rock cobble, preserve remaining cobble tread, and improve the overall length of the trail to enhance sustainability and user safety. Over the course of 15 workdays, including 14 days working with community volunteers and members of the GoPP, RMFI engaged a total of 182 volunteers who contributed 1,056 hours of volunteer time valued at $24,885 (at $23.56 per hour, independentsector.org). RMFI staff contributed another 403 hours during these days. Accomplishments at the Palmer Point Trail project site included 150 linear feet of trail improved, 2 drains constructed, 395 linear feet of social trail closed and restored, and stabilization of 165 linear feet of erosion gully and head-cuts using 10 rock check-dams, rock step-falls, re-seeding, and transplants. At the Edna Mae Trail project site, 250 linear feet of trail were improved to sustainable and safe condition, including intensive construction and repair of 815 square feet of rock-cobbling, construction of 15 rock steps, and construction of 4 drainage structures. BACKGROUND Palmer Park is located northeast of downtown Colorado Springs and is named after William Jackson Palmer, the founder of Colorado Springs. At 730 acres in size, the park is the largest park inside of the metro area. In total, it has over 25 miles of hiking and biking trails, a dog park, an off leash dog area, a community playground, picnic ground, and many other amenities. The highest altitude within the park is approximately 6,610 feet. The park is characterized by large sandstone bluffs, scrub oak, ponderosa pine, Douglas fir, and an abundance of wildlife. The trails in Palmer Park often climb quickly through steep terrain and over highly erodible soils. Coupled with recent heavy rains and increasing recreational use, many trails in the park have become eroded and damaged, which has led to the establishment of undesignated social trails and drainage challenges in adjacent park properties and residences.

3 Rocky Mountain Field Institute 3 The Palmer Point Trail runs just inside the northwest boundary of the park, offering visitors access to piñon-juniper and native grassland areas between the bluffs in the center of the park and the neighborhoods bordering the park. The Edna Mae Nature Trail ascends the central bluffs through forested slopes on sandy and gravelly soils. The trail is paralleled by a major drainage on this ascent and is crossed in several points by minor drainages. Significant portions of this trail are paved in a cobblestone fashion by nearby sedimentary rock, which was installed by Civilian Conservation Corps crews in the 1930s WORK OBJECTIVES The objectives of RMFI s 2016 stewardship project in Palmer Park focused on 2 key sites detailed below: Palmer Point Trail: o Reduce concentrated drainage and sediment run off from the Palmer Point Trail in the vicinity of private residences adjacent to the park boundary within the Caddie Court cul-de-sac. o Stabilize erosion gullies and an approximately 300-foot unsustainable segment of the Palmer Point Trail in the vicinity of this neighborhood. Edna Mae Bennett Nature Trail: o Stabilize damaged and eroded segments of the trail where it was paved by historic rock cobble, and improve the overall length of trail to ensure a more sustainable and safer trail. WORK NARRATIVE Project objectives at each of the 2 sites were accomplished with oversight from trained RMFI field staff and with significant volunteer support. GoPP leadership was very helpful in publicizing volunteer needs and opportunities to their active membership base. An average volunteer day was 6.5 hours long however, RMFI adjusted the duration of some workdays to meet the expectation of volunteers. Volunteers were initially given an orientation including an introduction to Palmer Park, the work site, and project goals. Volunteers were also briefed on environmental and safety hazards as well as proper use of tools. RMFI supplied all tools and personal protective equipment for use by the volunteers. RMFI staff assigned volunteers with specific tasks based on project needs and volunteer interests. Activities included building erosion control check-dams, moving rock and soil to fill incised gullies and social trails, restoring closed social trails, constructing rock steps and drains on designated trails, and installing rock cobble as a paved tread. RMFI field instructors, trained in restoration techniques, trail construction, and volunteer management, supervised all work events.

4 Rocky Mountain Field Institute 4 Of the techniques employed, construction of rock-paved tread was the most time-intensive and required the closest volunteer supervision to replicate the existing, historic cobble and to achieve a durable and dependable tread. GoPP crew leaders were a great help on all project tasks, but were particularly exceptional on this task WORK SITES Palmer Point Trail: The Palmer Point Trail is a multi-use trail that runs along the northwest border of the park. Classified as an advanced-skills trail for cyclists, it generally transits terrain that slopes from the foot of the central bluffs down to the neighborhoods just outside of the park. Much of this fringe area is vegetated with scrub oak and grassland. In sections without adequate drainage, this trail quickly accumulates water originating from upslope, and channels this water until the next available natural break in grade allows concentrated water and sediment to leave the trail on the neighborhood side. The project site centered on one 300-foot segment of the trail and the trail s surroundings, located immediately upslope from residences in the Caddie Court cul-desac. Approximately 150 feet of this segment of trail had become heavily eroded into a gully that measured 3 feet in depth and 6 feet in width (Figure 1). Trail users no longer used this segment, having established a Figure Figure 1. Photo 1. A group of the of intersection volunteers from of the the gully Latter (left Day fork) Saints and the Church lower work end to of restore the user-created a social trail bypass, in Valley Reservoir Number One. before stabilization work. Note aggradation of sediment in the foreground and the neighbor-installed expedient timber structure to stem flows uphill of residences to the right. gentler bypass that connected above and below the gully as a preferred trail alignment. Water concentrated in this gully, as well as in another smaller gully nearby, transporting significant amounts of sediment to the adjoining neighborhood. The gullies had reportedly grown substantially in size after major rain events in the fall of 2013 and spring of In addition, both gullies were continuing to be impacted by a small network of eroding social trails and a natural swale located upslope. User activity suggested that hikers were utilizing the social trails to access the popular Templeton Trail on the bluffs.

5 Rocky Mountain Field Institute 5 To address the concerns at this site, RMFI and PRCS staff felt the best and most long-term solution would be to re-route this section of Palmer Point Trail higher on the cross-slope, following the natural contour through oak shrubbery to separate drainage from the neighborhoods and to help keep users on-trail. However, this approach would have required additional coordination, planning, and time to implement. To immediately address the concerns, RMFI and PRCS staff settled on a short-term approach, which involved formalizing use of the user-created bypass segment, forcing drainage off of the trail above the bypass into heavy vegetation, adding drainage to the bypass segment, closing and stabilizing the large gully, and to addressing the network of social trails upslope of the gully and bypass. Special consideration in the approach was given to mountain bike riders, who made up a high percentage of usage of this trail segment. RMFI implemented this near-term approach over the course of 4 workdays in April using a RMFI crew of 6 field staff as the core workforce, with volunteers supplementing the crew on 3 of the 4 workdays. The crew and volunteers gathered and used on-site rock to close and stabilize the gullies with a rock wall (Figure 2), construct 10 rock check-dams, stabilize a large erosion head-cut in a swale up-trail from the gully, and build 2 large rolling grade-dip drainage structures to improve drainage (Figure 3). Several short segments of social trail, totaling 395 linear feet, were also closed and restored using the restoration technique detailed in Appendix B. Finally, the crew made improvements to sections of the new bypass and the original trail, which included constructing some small drains and armoring technical bike features to ensure this remained a sustainable trail. Figure 2. Before, during, and after photos of the large gully stabilization looking down towards the neighborhood with the bypass trail branching to the left. Rock head-cut stabilization was installed (foreground) and a series of check-dams installed periodically moving down the gully. The sides of the gully were seeded and deadfall was placed to discourage disturbance by trail users.

6 Rocky Mountain Field Institute 6 Figure 3. Addition of durable drainage was key on the Palmer Point Trail site. A grade-dip drain is shown draining into oak brush to disperse energy. Edna Mae Bennett Nature Trail: The Edna Mae Bennett Nature Trail is situated in the west-central portion of Palmer Park, just east of the Mark Reyner Stables. It ascends the central bluffs of the park through forested slopes on sandy and gravelly soils. The trail forms a 1-mile loop with the North Canyon Trailhead marking its start and end points. In its ascent and descent from the rim of the bluffs, the Edna Mae Trail parallels major drainages and is crossed in several points by minor drainages (Appendix C). Approximately half way along the loop, the trail joins the Templeton Trail. Templeton serves as the eastern portion of the loop before Edna Mae turns west to finish at the North Canyon Trailhead. The trail is a favorite among several user groups including mountain bikers, equestrians, and hikers. The latter comprises the highest user volume with mountain bikers coming in as a close second. Relative to the area, this trail is designated as requiring advanced riding skills, offering users a technical challenge for either a short loop or to gain access to other trail systems within the park. The trail was named after Edna Mae Bennett, an active Colorado Springs community member, in recognition of her leadership role in a city-sponsored program created to acquaint fourth graders with the natural world. This trail is where Edna led hundreds of children on nature walks to teach them of nature s many wonders. A significant length of the trail s north end features cobblestone paving fashioned from nearby sandstone (Figures 4 and 5). This specialized trail tread is believed to have been constructed by Civilian Conservation Corps crews in the 1930s. Years of intensive use and heavy precipitation in May 2015 have displaced many of the pavers and stone steps, and deeply incised the trail. Due to this degradation, much of the cross-trail drainage no longer functions and a few sections pose some safety hazards to users. In a few segments, the original cobblestone-paver tread remains, largely undamaged, to suggest the manner in which they were installed. With assistance from PRCS and GoPP, RMFI identified high priority sections to address in the 2016 field season in order to restore this as a sustainable trail while preserving its historic qualities.

7 Rocky Mountain Field Institute 7 Figure 4. Large paver rocks help ensure trail durability. The larger rocks were best carried over challenging terrain using team carry techniques. Figure 5. Before and after photos of repairs made in one of many areas of heavy erosion where most historic pavers had been lost. Volunteers and staff working on this project found recreating the paving style of the 1930s to be both challenging and rewarding. The labor and timeintensive nature of cobbling, using irregular-shaped rock pavers, quickly became clear to RMFI staff in the first few days of the project. Repairing relatively intact areas of cobbled tread demanded creativity and a detail-oriented approach to fit new with old and to ensure stability. Installing new pavers in areas apart from existing cobbling required special focus to build consistent, durable tread. To ensure these results, RMFI staff placed substantial priority on maintaining a high ratio of staff and experienced crew leaders to volunteers. This method proved successful, as it provided volunteers with ample direction and continuous quality control. Work commenced on April 3, 2016 with a half day of cobble paving technique training including RMFI staff, five crew leaders, and several GoPP members. Over April and the next two months, two RMFI Field Instructors led 10.5 volunteer workdays in coordination with GoPP. Breaks during these workdays

8 Rocky Mountain Field Institute 8 often offered an opportunity for Field Instructors to teach volunteers about the historical significance of this trail. The project site focused on improving a 250-linear foot section of trail with emphasis on reconstructing cross-trail drainage, rocks steps, and pavers. This focus area began roughly a half-mile north of the North Canyon Trailhead and ended approximately 50 feet beyond the north intersection of Edna Mae and Templeton Trails. Throughout the project, the approach was to stabilize, not to replace, historic pavers and to emulate the durable paving techniques used by the CCC when installing replacement pavers. RMFI integrated other methods commonly used in its other rockwork projects, including rock steps and drainage structures to further ensure long-term integrity of the trail. The first task at this project site was to build a rock-reinforced grade dip situated below a steep section of cobbled tread. In this initial 80 feet, work concentrated on securing loose pavers, replacing missing portions of pavers that had washed out, and constructing a rock-reinforced grade dip. The typical cobbling process entailed sourcing materials from alongside the trail and in the nearby drainage, excavating the work area, laying pavers, and lastly securing around them with grout material using other onsite resources. See Appendix D for rock cobbling technique specifics. The next 50 linear feet of trail steepened again, leading up to a switchback. Work along this stretch included the construction of another armored drain as well as intensive tread paving. While this section did have sparse patches of existing cobble to stabilize, a majority of effort involved laying new cobble pavers to fill large gaps. It was also observed that several rock steps installed in this steep section by the CCC had shifted, creating additional safety hazards. RMFI repaired or replaced these sections with similar rock steps to improve overall stabilization. At the switchback, 3 rock steps where replaced and positioned closer to the critical edge to allow safe passage for cyclists in the tread s center. Additionally, the opportunity was taken to shed water off trail at this switchback by building a rock armored drain into the switchback. This structure now directs water into the major drainage paralleling the Edna Mae Trail. Continuing up another 50 feet to just below the intersection with the Templeton Trail, another rock step was installed to stabilize the remaining cobble tread above it. Beyond this step, more cobblestone paving was required, mostly installation of new pavers to fill gaps as only a few historic segments had survived intact. Just above this, the intersection of Edna Mae and Templeton Trails required significant repair and securing of historic pavers as well as replacement of a few rock steps (Figure 6). Approximately 40 feet past this intersection, the trail had become incised due to a failing water drainage structure above (Figure 7). Just below the same intersection, 4 timber riser steps had loosened and become extremely undercut. To stabilize this section, the incised area was armored with new pavers and the timber risers were removed and replaced with rock steps for durability. In addition, a large armored drain was built to replace the failed drainage structure to protect the new work below.

9 Rocky Mountain Field Institute 9 Figure 6. Before and after photos of the northern Edna Mae and Templeton Trail intersection. Many historical pavers had been washed out and more were soon to be lost. Volunteers installed new pavers to fill the gaps and to shore up intact sections of cobble and undercut steps. Upon conclusion of multiple weekend workdays, which were supported by GoPP volunteers and many other community volunteers, RMFI installed and repaired 815 square feet of rockcobbling, built 15 rock steps, and constructed 4 drainage structures, over 250 linear feet of repaired and improved trail WORK ACCOMPLISHMENTS The community response to repairing these 2 critical trail segments in Palmer Park was a testament to the great support that local residents and GoPP continue to give to this park year in and year out. The park s staff were always prepared to help facilitate the project and were another reason for its success. Learning the technique and refining paver cobbling skills was a great opportunity for RMFI staff and the volunteer crew leaders of RMFI and GoPP to expand their technical expertise.

10 Rocky Mountain Field Institute 10 Figure 7. Before and after photos of replacement of loose timber riser steps with rock steps and installation of pavers in cobblestone fashion to stabilize trail tread. A paved drain was installed further up-trail to protect these repairs. Palmer Point Trail: 165 linear feet of gully (2 gullies) stabilized. 10 rock check-dams constructed. 2 erosion head-cuts stabilized with rock-step fall structure. 395 linear feet of social trails closed and restored. 300 linear feet of trail improved. 2 large rolling grade-dip drainage structures constructed. Several areas of tread around bike features armored with rock. Edna Mae Nature Trail: 250 linear feet of trail repaired to sustainable condition. 850 square feet of cobblestone/paver tread repaired and constructed. 4 rock-paved grade-dip drains constructed. 15 rock steps built (most replacing damaged or missing steps).

11 Rocky Mountain Field Institute VOLUNTEER STATISTICS Volunteer workdays: 14 Number of volunteers engaged: 182 Total volunteer hours: 1,056 Value of volunteer time: $24,885 ($23.56/hour, independentsector.org) Volunteer Organizations Engaged: 1. Guardians of Palmer Park 2. United States Air Force Academy 3. University of Colorado at Colorado Springs 4. University of Denver 5. The Mission Continues (Veterans community volunteer program) 6. Peterson Air Force Base 7. Refuge Student Church FUTURE WORK Earlier this month, representatives from RMFI, PRCS, and GoPP conducted a site visit to discuss future work objectives in Palmer Park. The Park Ranger suggested that RMFI could be especially helpful in continuing trail repair and stability work on other portions of the Edna Mae Trail where park staff can t easily access with machinery. The first area of interest is just above and just below where 2016 work was completed and involves continued cobbling installation and repair, additional drainage construction, and repairing a section of significant trail incision, possibly with use of sub-surface stabilization timbers (Appendix C). A second area that may require attention is the southeast portion of the Edna Mae Trail, where the trail ascends the mesa to its southern intersection with the Templeton Trail. Along this stretch of trail, objectives would be to repair rock steps and timber risers, to install drainage, and to assist with trail way-finding and trail delineation. CONTACT INFORMATION Joe Lavorini RMFI Program Director joe@rmfi.org

12 Rocky Mountain Field Institute 12 APPENDIX A. Overview Map of 2016 Work Areas in Palmer Park

13 Rocky Mountain Field Institute 13 APPENDIX B. Social Trail Closure and Restoration Technique RMFI s restoration prescription for restoring social trails and erosion gullies: Decompact and aerate hardened surfaces (soil tilled between 4 and 6 inches in depth). If the area is gullied, use native soil to bring the gully back up to grade with the surrounding area. Install subsurface check-dams if gullies allow water to gain significant velocity. Subsurface check-dams are below ground rock structures that stabilize the slope and keep soils in place. Prep the soil seedbed by removing large rocks and smoothing the soil s surface. Spread and rake in native seed mix. On steep slopes, aspen-fiber (or excelsior) erosion control matting is installed and secured with 4-inch biodegradable stakes. Each side of the matting is trenched and stakes are pounded in angled toward the outside edge of the matting. The trenches are then covered with dirt to create a seamless transition between surrounding soil and the matting, preventing water flow under the matting. In areas where there is little to no slope, mulch can be used as an alternative to matting. The purpose of the mulch or matting is to provide cover for newly spread soil and seed on restored areas. Dead and downed branches or slash are placed on the matting for additional stabilization and to provide a microclimate for the seed. Leaf litter is also scattered to help lessen the visual disturbance of the bright yellow matting. Split-rail fencing and educational signs are installed.

14 Rocky Mountain Field Institute 14 APPENDIX C. Map of 2016 and Potential 2017 Work on Edna Mae Trail

15 Rocky Mountain Field Institute 15 APPENDIX D. Rock Cobbling Technique with Natural Pavers - Work on Edna Mae Trail Source on-site rock when possible for pavers, looking for the following characteristics: large as possible (requires use of rock carrying device (RCD) and large hand-carries), solid, and ideally square or rectangular-shaped with mainly flat surfaces. If pavers are not recto-linear, a bit more creativity is required to assemble paver rocks in a jigsaw puzzle fashion. Source other rock that is soft or friable in composition (need to be able to break into less than ¼ inch pieces using single-jack) and source sandy or clay-bearing soil to install as grout material. This material will be used to secure pavers in place. Excavate 6 to 8 or more in the area where cobble will be set to uncover obstructions and shape a smooth foundation to begin laying cobble. Set cobble pavers with these key points in mind: (1) Bigger pavers are less likely to move and come out as compared to smaller ones; use smaller pavers to fill large gaps between larger pavers. (2) Ensure multiple points of rock to rock contact (at least 3 points) when placing pavers so that individual pavers do not move easily (even before grouting in place). (3) Form the cobbled-tread in a manner that channels water off of the trail via out-sloping or in conjunction with a drainage structure. (4) Create safer trail by avoiding protrusions that could pose a safety hazard or weaken the integrity of paving. Intensively crush a mixture of friable rock and soil between pavers to secure cobblestone using a single-jack and rebar. Use mostly crushed rock while filling voids. Clay-bearing soil (if available) is often useful as a finishing top layer.