MPS Trail Construction BMPs (190821).pdf

Best Practices for Natural Surface Trail Construction

Maryland Park Service Version 1.1 - February 2019

SECTION 1: GENERAL

1.1 Open Job Site And Public Safety

It is likely that the job site is reachable by the general public. Contractor shall ensure that reasonable precautions are taken to protect the public at all times where work is being performed.

This includes but is not limited to: clearly marking trail entrances to construction area as closed ideally with suggested alternate routes to circumnavigate affected areas, not using the greater trails system for mechanized access without informing the public and/or using dedicated spotters, employing dedicated spotters when felling trees or performing other tasks which may have effects outside the immediate construction area.

1.2 Invasive Species

To reduce the spread of invasive plant species all hand tools and mechanized equipment should be free of invasive seeds and clean of any dirt and mud when entering a project site. When transferring materials between distinct locations within the project site all tools and equipment must again be cleaned to discourage transport of invasives in the local landscape.

1.3 Disposal of Materials and Supplies Not Used

Materials, supplies, etc., delivered to the job but not used shall be removed from the site and properly disposed of by the Contractor.

1.4 Access Control

The Contractor is prohibited from installing gates, cables, chains, fences, and other types of barricades to limit access to the project site without prior written permission from the client and land manager.

SECTION 2: EROSION AND SEDIMENTATION CONTROL

2.1 Introduction

Management of erosion and sediment on a project may be defined in a provided

Storm Water Pollution Prevention Plan (SWPPP). In such cases, all construction activities must conform to the requirements of the SWPPP. Any inconsistencies created

Maryland Park Service - Best Practices for Natural Surface Trail Construction (190212) 1 by the construction specifications do not excuse the Contractor violating the procedures and requirements laid out in the SWPPP.

No excavation or fill is permitted in wetlands. Wetlands will not be marked in the field. It is the responsibility of the Contractor to consult with client prior to doing any work within suspected wetlands areas.

2.2 Excavation + Finishing Sequence

To satisfy general erosion and sediment control concerns, trail must be finished and stabilized as the project advances. Ideally, all roughed-in corridor will be finished the same day. Stabilization includes covering excavated areas with local forest duff or approved alternate materials. Any segments requiring delayed finishing (e.g. greater than seven (7) days) must be approved in advance by client.

2.3 Filter Strips

Filter strips are vegetated areas downslope of the trail corridor intended to treat sheet flows coming off the tread. Filter strips function by slowing down flow velocities, filtering out sediments, and providing an opportunity for infiltration into the underlying soils. Properly mulched spoils may be designated as part of the filter strip. Filter strips shall not be used as regular travelways for equipment and materials. Areas with inadequate filter strip capacity above waterways may require installation of formal erosion control measures to satisfy erosion and sediment control plan requirements.

At all times, filter strip characteristics must satisfy the terms of the project SWPPP.

2.4 Filter Logs

Filter Logs are commonly specified in a trail project SWPPP when it is expected that buffers/filter strips cannot be maintained to wetland/waterway features. Logs must be installed to comply with Maryland Department of the Environment erosion and sedimentation control standards. Logs which are 100% biodegradable (e.g. no plastic netting) are strongly suggested so there is the option to leave logs in-place to degrade.

Log staking should be done to comply with standards while also reducing the fall risk to trail users.

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SECTION 3: TRAIL CONSTRUCTION

3.1 Detailed Design

Many projects are defined by a center-line corridor leaving it to the Contractor to layout a detailed design within the bounds of that corridor. This document and its recommendations do not constitute a design manual. The Contractor is expected to be familiar with the sustainable natural-surface recreation trail design principals promulgated by resources such as the US Forest Service Trail Construction and Maintenance Notebook and the International Mountain Bicycling Association Trail Solutions: IMBA’s Guide to Building Sweet Singletrack.

Rolling Contour Alignment is a Cornerstone of Sustainable Trail Design

3.2 Corridor Clearing

Corridor clearing shall be confined to within four (4) feet of trail and backslope edges or as detailed in the project specifications. Within the specifications, pruning should be done with a light touch (invasive species excepted), only removing materials necessary to clear route and create sightlines. Proper pruning technique includes cutting limbs at intersections and not leaving staubs or “coat hangers”. Always use proper pruning equipment; not acceptable to snap off branches, slash with a machete, etc.

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3.3 Trees

The trail is to be built with minimal impact to the over story trees and the surrounding forest. Only brush and small trees should be removed from the trail corridor. Live trees larger than 6” DBH or as listed in project specifications require permission before they are removed. Removal of healthy trees approaching this size should be avoided and only done when there is not a better option. Non-merchantable timber, dead, dying, and rotted trees can be removed to open up the trail corridor as necessary for grading or if they present a clear hazard to trail builders or trail users.

3.4 Debris

No debris created by construction activities shall be left within ten feet (10’) of trail.

Butt-ends of any sawed limbs must face away from trail. Cut brush and slash must be disposed of in an upland location and must be kept out of streams, gullies, swales, low areas, and suspected wetlands. Distribution of slash should mimic the natural scatter in the local area.

3.5 Tread

All tread should be constructed as full bench whenever possible. If fill is required, it should be supported by a stone retaining wall sufficient to support potential equestrian use. In flatter areas (LT 10%), trail building techniques such as “lift and tilt” are expected to establish long-term positive drainage.

Specific tread widths are a function of the project and will be defined in its specifications. Narrower gateways through natural obstacles (trees, rock outcrops) are encouraged. For trails where the primary managed-use is bicycles, tread widths in areas of dynamic flow, jump landings, and insloped turns, for example, may be wider to accommodate the full range of riding experiences. Significant deviations from these examples require approval of the client.

3.6 Rocks

Maximum size rock material to be left in trail is a function of the project and will be defined in its specifications Rocks that are unearthed during grading shall be built into trail features or stabilized not more than five feet (5’) away from the trail-edge. It is not permitted to allow rocks to roll down the slope. The trail will be routed around or over rocks that cannot be moved with the approved equipment.

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These requirements do not apply in areas where rocky tread is integral to the flow goals of a specific segment (e.g., more challenging “blue” or “black” graded).

Exceptions also apply in boulder fields or where only a portion of the tread is obstructed.

All rock embedded in the trail surface should be stable. When used in structures, care will be taken to match rock to the immediate surroundings; grain patterns, lichen growth, etc. Excess tool marks on rocks is not acceptable. Non-native rock may not be imported into a work area without approval.

Bench Cut Trails Feature a Fully-Excavated Tread

3.7 Woody Material

Woody material such as stumps, logs, brush, and roots shall be removed from the trail tread. No standing stumps less than twelve inches (12”) in diameter shall be left within four feet (4’) of the trail tread.

3.8 Fall Zone Clearing

Areas adjacent to dynamic trail segments where visitors have a greater potential to exit the immediate trail corridor will be cleared of impact focusers; butt-end branches, stumps, and rocks under six-inch (6”) diameter.

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3.9 Backslope

Backslope of trail should be graded to the angle-of-repose of the local soil or until it matches the existing slope. In areas where the backslope has the potential to become part of the active tread it must be finished to trail tread specifications.

3.10 Trail, Finished Condition

Finishing extends beyond the trail tread to include backslope, down slope spoils, and drainage features. It is not acceptable to remove roots and other debris from the trail tread only to leave them protruding from backslope.. Spoils rakedown should take care to remove large debris as well so as to match the surrounding forest floor.

3.11 Spoils Stabilization

All excavated materials not used in the trail tread or other trail structures must be stabilized within seven (7) days of not being worked. Spoils should be distributed in a thin layer adjacent to the trail tread. Care should be taken to avoid placing spoils in drainages or swales. When possible, spoils should be mulched with local materials to discourage erosion while native seed stocks reestablish. In areas without adequate native mulch, appropriate alternative materials will be specified appropriate to the site.

In certain circumstances, installation of formal erosion control measures may be required.

At all times, spoils stabilization must satisfy the terms of the project SWPPP.

3.12 Grade Reversals

A designed grade reversal or constructed rolling grade dip should occur at least every one hundred feet (100’) and preferably more frequently. Any grade reversal must be strongly anchored to discourage short cutting.

For trails where the primary managed-use is bicycles, grade reversals may also double as flow elements, such as rollers, jumps, and pump/rhythm sections. In this context grade reversal shape, size, and placement should reflect the specifications for its location within the system.

3.13 Turns

A turn is a change of direction that results in crossing the fall-line of the hillslope.

Turns will be constructed according to the trail tread specifications with the addition of a mandatory grade reversal upslope/prior to the turn and downslope/following the turn.

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Turns should be designed and constructed to maintain a consistent radius. Project specifications may include turn radius guidelines. Projects with a primary-use for bicycles may specify the trail tread of the turn be insloped. Turns across slopes greater than 20% (or as defined in project specifications) require the creation of a platform to lessen the grade change through the turn. A switchback is an example of a platform turn. Turn platforms must be constructed to satisfy the terms of Above-Grade Earthen Structures.

Turns Crossing the Fall Line are Anchored by Leading + Trailing Grade Reversals

3.14 Above-Grade Earthen Structures

Any portion of trail rising above the grade of its surroundings must be composed of mineral soil. If soil is scarce, a rock core may be used so long as it provides less than fifty percent (50%) of the total volume of the structure. Use of organic materials, duff, woody materials, etc., is absolutely prohibited.

Fill structures must have a fill slope of at least two-to-one (2:1) or the angle-of-repose of the local soil, whichever is greater. A retaining wall may be substituted for a fill slope with permission of the client. Fill structures must be completely stabilized and compacted in no greater than six-inch (6”) lifts. Acceptable techniques include track-packing or compaction via a dedicated tamping unit. Hand tamping is not acceptable. Raw soil faces that do not become tread must be mulched and seeded in the same fashion as spoils and satisfy the terms of the project SWPPP.

Examples of above-grade earthen structures include aggressive grade reversals and turn pads for platform turns.

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3.15 Borrow Pits

If borrow pits are created in the course of trail construction they will be finished to satisfy the requirements of the trail and its surroundings: slopes graded to the local angle of repose, stumps and roots trimmed, spoils stabilized and covered with forest duff.

3.16 Water Diversions

All tread should be outsloped at three percent (3%). When not possible or desirable due to purpose-built insloping, resource concerns, or obstruction, water can be directed down the trail for up to fifty feet (50’) before a water diversion location.

3.17 Environmental and Historic Preservation

The corridors identified in the provided design have been vetted through an assessment process to ensure they respect sensitive environmental and historic areas.

The construction shall avoid any disruption or dislocation of sensitive cultural resources found on the site unless expressly authorized in writing by the client. Any known sensitive cultural areas will be communicated to the Contractor in writing before construction begins. In the event that previously unidentified historical artifacts are found during the construction process, trail construction must be immediately suspended in that area until it can be evaluated and a determination made on how to proceed.

3.18 Trail Closure

Closure specifications apply to temporary access routes and to existing trails being reclaimed as part of project scope. Compacted tread will be scarified to encourage regrowth of native seed stock. Exposed soils will be covered with local leaf litter. Seed and mulch meeting the mix requirements of the SWPPP may be used in this application.

Trail tread will be disguised with woody debris. If trail is incised, check dams will be placed at a minimum of every twenty feet (20’) to capture sediment. If trail is actively eroding, grade reversals will be added to stem continued damage. Trail corridor will be erased via the placement of vertical debris. If length of trail to be closed is greater than one hundred (100) linear feet than vertical debris must extend a minimum of fifty feet (50’) from each end or until visible sight line is diminished, whichever is greater.

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SECTION 4: MECHANIZED EQUIPMENT BEST PRACTICES

4.1 Utility Location

An active “Miss Utility” ticket must be open whenever construction operations are occuring. It is the Contractor’s responsibility to manage these tickets.

4.2 Tools

The Contractor shall perform the required work using hand tools and/or small mechanized equipment that is a maximum of fifty inches (50”) in width. Equipment with adjustable width tracks should be able to reduce track width to less than fifty inches (50”). Some sites may not be suitable for equipment this large and other sites may not be suitable for any mechanized equipment regardless of size due to terrain constraints.

Larger equipment may only be substituted with prior expressed permission of the client.

Permanent modification of trail outside the scope of work to accommodate equipment access (e.g., widening of an existing trail) is not desirable and must be specifically approved in advance by the client.

4.3 Mechanized Equipment; Use

All track marks will be raked smooth. Affected area will be finished to have a nature shape, e.g., spoils piles rounded, smoothed and cleared of significant brush, blade edges blended. A spill kit suitable for five gallons of fluid will be onsite and within 500 feet of mechanized equipment whenever equipment is being operated. Scarring of trees is to be avoided. Significant and repeated scarring may result in a financial penalty up to the replacement value.

Machine service and fueling is not permitted with 100 feet of a wetland or drainage.

Machine access is restricted to the trail corridor. Separate access routes may only be created and used with the prior permission of the client. Any approved access route must be retired and reclaimed back to its original condition upon project completion.

Contractor should confirm the capacity of any structure (e.g. bridge, culvert, etc) before using. Damage to any road/trail or structure caused by the Contractor’s use will be repaired at their expense. If equipment with metal tracks are used, the Contractor is expected to employ best-practices, such as the use of rubber mats, to protect facility infrastructure during loading/unloading, site mobilization, etc.

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4.4 Mechanized Equipment; Requirements

Using mechanized equipment equipped with tracks is strongly recommended. On project work, tracks are required for heavy equipment (greater than 500 lbs. gross weight).

All equipment will be clean and free of debris before introduced to work site.

Equipment is subject to inspection at the start and during the project.

All mechanized equipment shall be in good mechanical condition, free of any fluid leaks and be equipped with spark arrestors if applicable.

Each machine will be equipped with at least one readily accessible fully charged fire extinguisher. Mounting locations should be chosen such that at least one fire extinguisher is accessible in the event of a rollover.

A spill kit with appropriate capacity must be mounted on the machine or available within 500 feet whenever equipment is operating.

Any equipment that does not meet these criteria shall be shutdown until in compliance. If not correctable it will be removed from the project site at the request of the client’s representative and at no additional cost to the client.

As part of their bid package, the Contractor will be asked to supply the expected list of mechanized equipment required to complete the project.

4.5 Personal Protective Equipment

It is the responsibility of the Contractor to ensure that all employees working on the project equipped with and are using as appropriate the proper Personal Protective Equipment (PPE) for the work being done. Helmets, eye protection, hearing protection, protective gloves, steel-toed boots, and protective clothing are considered some of the basic PPE. Face shields, breath protection, insect repellent, knee pads, shin guards, chaps are some of the other PPE that should be deployed where appropriate for the work being performed and the conditions. The Contractor must have at least one OSHA-compliant First Aid Kit readily available at each worksite.

4.6 Use of Premises – Storage

Contractor shall confine its apparatus, storage of materials, and operation of its employees/subcontractors to limits indicated by law, ordinance, permits, and/or directions of the client, and shall not unreasonably encumber the premises with it’s materials. Before any work is undertaken the Contractor shall consult with the client’s representative and secure from client the use of such space as may be available for the

Maryland Park Service - Best Practices for Natural Surface Trail Construction (190212) 10 storage of materials and/or equipment. Contractor will be held responsible for any damage done in connection with the use of this location for storage.

The client is not responsible for any damages that may occur to the Contractor’s equipment during storage whether it is from natural causes or caused by man from such unlawful acts as theft, vandalism, and arson. The Contractor is responsible for providing their own property insurance. The Contractor is responsible for providing their own storage and transportation equipment such as trailers, tarps, locks, or other security devices.

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