B08_22Q0043_Attachment_1_Three_Rivers_Petroglyph_Recreation_Trail_ADA_Construction_SOW.pdf

Three Rivers Petroglyph Recreation Trail ADA Construction Statement of Work

Introduction:

The Three Rivers Petroglyph Site is located in Otero County, New Mexico. The site is about 17 miles north of Tularosa, New Mexico within Section 21, Township 11 South, Range 09 West. It may be accessed from Three Rivers Road, off US Highway 54 to, all paved roads.

The site is open to the public year‐round and has a camp host, visitor center, picnic ramadas and public restrooms.

Dense clusters of rock petroglyphs exist throughout the Three Rivers Hills, and a significant number are viewable from the Petroglyph Trail and viewing platform. The platform is located at the south end of the hills and is accessed from the visitor area via the Petroglyph Trail. The trail crosses a minor wash with a pedestrian bridge; the existing walking surfaces of the trail and viewing platform are graded and compacted native soil, edged with hand‐placed local rocks averaging 10” to 24”.

The Pueblo Trail to the south of Three Rivers Road is also gravel and edged with hand‐placed rocks. The trail is quite level and drops about 6 feet in 800 feet toward Three Rivers arroyo, but most of that grade is within the first 200 feet, toward a low point that is frequently washed out by storm water crossing it.

Improvements to petroglyph trail and viewing platform:

The construction will provide a safe path that is fully accessible. The trail will be paved with concrete and will meet the requirements of the Architectural Barriers Act (ABA) as well as the Americans with

Disabilities Act (ADA). The proposed walk is 5 feet wide, concrete with a cross‐slope of 1.5% and maximum longitudinal slopes of less than 5% for up to thirty feet. Please refer to the plans, Appendix A.

Grades adjacent to the new sidewalk are to remain undisturbed other than removal and salvage of the hand‐placed rock bordering the path. The walk will be elevated above adjacent grade a minimum of one inch; where more than four inches above grade the sidewalk will be constructed with a stem wall of up to eight inches. Storm water will cross the path at regular intervals through scuppers aligned with existing drainage crossings. The first 70 feet of sidewalk from the ramada to the footbridge is cross sloped to the north to match existing grades. West of the footbridge the sidewalk slopes at 1.5% toward the south. About 85 feet past the footbridge an existing 18‐inch corrugated metal pipe (CMP) conveys a

100‐year peak flow of 18 cfs under the path. The CMP will be replaced with a sidewalk scupper with handrail on the south edge of sidewalk. To the west, minor runoff that collects and runs along the north side of the walk will drain through smaller scuppers. Pavement will be a standard 4‐inch sidewalk of

3,000 psi cement cast in place on compacted native subgrade. A light broom finish transverse to the path and between the scored lines will provide light traction. The salvaged rocks mentioned above will be relocated along the edges where the path is highest, to provide a visual warning about the edge as well as to protect it from erosion. A tooled score line six inches from each edge also provides visual and tactile reminder of the edge. The viewing platform will also be paved, with a varying width matching the current extents of the area. The sidewalk surface will slope from the center outward at 1.5% and continue the light broom finish. Concrete will stop a minimum of 18 inches from the existing stacked boulders, and the space between boulders and sidewalk will be graded to drain to the west and covered with a 2‐inch layer of gravel. Pavement will meet the edge of the existing binocular viewer foundation, allowing the device to be restored in place. The bench will be salvaged and bolted to the new concrete surface in place.

Improvements to Pueblo Trail:

This path will be stabilized for foot traffic and weather while minimizing disturbance to the abundance of cultural artifacts on and near the trail. The trail follows a historical footpath and is not intended to meet all requirements of the ABA or ADA. The trail will meet ADA grades but will vary in width from three to five feet, with a rough granular surface comprised of a 50‐50 mix of the onsite topsoil mixed with imported gravel, fixed in place with a polymer stabilizer or binder and landscape edging. Polymer stabilizers for earthen surfaces are available from several manufacturers and are generally capable of producing a wear surface for all types of traffic. They may come in a ready to use liquid form, or a concentrate or powder for mixing. The important properties for this project include non‐toxic to the environment, clear (or may be tinted if desired) and quick to apply and cure. Consideration should also be given to the ease with which repairs to any damage on the trail can be made in the future.

Each product specifies a best method of application. These may include a range of methods from sprayed‐on or sprinkled into the granular surface then raked in, to removal of the surface, mixing in the binder, placing and compacting the mixture. Each product will recommend an application rate for a given gradation of soils, which allows BLM flexibility when selecting the imported gravel for the surface.

Metal edging is preferred for resistance to UV degradation, but a rubber, HDPE or recycled plastics material may be used if BLM is satisfied with the material warranty. Other materials may allow more choice of color and appearance. The edging is proposed to meet the top of the stabilized surface at 2 inches of height, with about a 1‐inch reveal on the outside of the trail. Salvaged rocks lining the trail, replaced along the edges to encourage hikers to stay on the trail, will obscure most of the edging from view away from the trail. The proposed edging is L‐shaped to provide stability while allowing a minimum of nails driven into the bottom of the L to secure it in place. An edging with built‐in spikes should be avoided due to the greater ground disturbance required. Edging must be flexible to accommodate the existing path meander, but no curves will be less than a 5‐foot radius. One stormwater crossing over the trail approximately 200 feet south of Three Rivers Road will be concrete‐ paved for 25 feet, with concrete toe‐downs on upstream and downstream sides. The trail currently gets washed out by runoff from the small watershed draining to this point, with an estimated 10‐year peak flow of 8.8 cfs. A portion of this runoff comes from the drainage ditch along the south side of Three

Rivers Road and may be mitigated by repair of a washed out point in the backslope of the ditch. All improvements will be monitored to preserve and protect any artifacts and implemented to minimize disturbance to the site.

The driveway entrance to the site will have a 24” culvert replaced to extend the pipe length to accommodate a full turned entrance and trail. The culvert length is estimated to be 60 feet with tapered end sections.

All material requirements are to be verified by contractor.

Cultural Resource Monitor:

During all ground disturbing activates the contractor is required to have sub‐contracted an independent archeological monitor on site. The monitor will be from the Firms Permitted list attached.

Site construction shall be planned with contracting officer to start on or about October 24, 2022.