J1 - Project Details.pdf

Project Details

Upper Williams Road Decommissioning (South)

CIM-0921-10EW-381-0921-01

Project Details Page 1 of 5

The governing specifications for this contract, The Standard Specifications for Construction of Roads and

Bridges on Federal Highway Projects, FP-03, USDOT, will be modified in accordance with the following language.

211-ROAD OBLITERATION

Add the following:

Outsloping

In areas requiring outsloping, all road surfaces not being excavated will be decompacted to a minimum of 12 inches. Material from the fill slope will be excavated to obtain the minimum outslope required for each area as identified in the project drawings and associated table. Outsloping will be completed in a manner that results in a gradual transition between the newly established grade and the existing slopes immediately adjacent to the treated areas. Where the natural slope above and below the road corridor is less than the degree of outsloping prescribed for the road (for example, 15%), the final outslope of the road shall match that of the natural grade. If material on site is not sufficient to obtain the outslope prescription, the greatest degree of outsloping that can be attained with the material on site shall be sufficient.

In areas requiring a concave surface, the road will be decompacted and some of the fill removed without being placed on the cut slope, leaving a concave area remaining in the road corridor.

In areas requiring contractor to only decompact the road, the entire road surface will be decompacted, with any ditch or significant low spot filled in to prevent puddling of water.

In areas requiring full recontour, all fill material shall be brought to the cut slope in order to achieve a gradient as close as possible to the natural slope above and below the road. All road surfaces not being excavated will also be decompacted to a minimum of 12 inches. Material will not be brought in to achieve this recontour.

Where two roads intercept, the outsloping at this intersection shall be continuous.

Where roads cross streams, stream channels will be reconstructed to reflect and blend with more natural channel properties (channel width, depth, and gradient) found upstream and downstream from the road crossing. Further direction is provided in the General Notes, Project Drawings, and Road Logs.

All disturbed areas will be seeded and mulched.

Channel Restoration Sites and Stream Crossings

Stream channels will be reconstructed at road crossings to reflect and blend with more natural channel conditions found upstream and downstream of these crossings. This work will conform to direction found in the General Notes, Project Drawings, and Road Logs. All disturbed areas will be seeded and mulched.

Vernal Pool Creation

The Road Logs identify locations where small, shallow vernal pools will be created. Vernal pools will be created by excavating a shallow concave area that spans approximately 75% of the road width, possesses a maximum depth of 18 inches, and has a length as specified in the Road Logs. The area that will function as

Project Details Page 2 of 5 the bottom of the vernal pool will not be decompacted in order to facilitate seasonal puddling of water for various wildlife species.

211.01(b) Relief Dips Ditch Relief Dips

Construct a ditch relief dip across the road prism at the locations indicated in the Road Log and Project

Drawings. These dips will be constructed to transport all water from the existing inside ditch along the road to the downhill (opposite) side of the road prism while the road is in storage. Where road surface gravel exists in the areas to be excavated, gravels will be scraped off and stock-piled during construction of ditch relief dips. Ultimately, stock-piled gravel will be placed as an armoring layer in the bottom (as the priority) and along the lower sides of the completed dips. Spoil material produced during dip excavation will be wasted on the downslope side of the dip in a manner that will be stable. This material must first be used to plug the inside road ditch to prevent water from bypassing the ditch relief dip and continuing down the existing inside road ditch.

Ditch relief dips will be constructed so that that the bottom of the inlet of the dip is approximately 6 inches lower than the bottom of the existing inside road ditch. Ditch relief dips will be oriented at approximately 120 degrees in a downstream direction in relation to the inside road ditch to provide a persistent and smooth transition for water flowing from the existing inside road ditch through the constructed ditch relief dip. Ditch relief dips will be constructed with an outslope gradient of 3-10% across the road. The width will be similar to the width of the existing inside road ditch being relieved. The finished sides of the dip will be at a stable angle that will not exceed a 50% gradient. The depth of the dip will be dictated by its width, outslope gradient, and sideslope gradient. All disturbed areas will be seeded and mulched.

Culvert Relief Dips

Construct a culvert relief dip across the road prism at the locations indicated in the Road Log and Project

Drawings. These dips will be constructed to accept water being routed to a target culvert only if that culvert should plug or otherwise fail while the road is in storage. Culvert relief dips are not intended to intercept water as long as the target culvert is functioning properly.

Culvert relief dips will be positioned close enough to their target culverts to best serve their intended purpose yet be offset from them enough to avoid undermining the stability of these culverts. Where road surface gravel exists in the areas to be excavated, gravel will be scraped off and stock-piled during construction of culvert relief dips. Ultimately, stock-piled gravel will be placed as an armoring layer in the bottom (as the priority) and along the lower sides of the completed dips. Spoil material produced during dip excavation will be used first to plug the inside ditch on the downslope side of the culvert, and secondarily along the downslope side of the dip.

Culvert relief dips will be constructed so that the bottom of the dip at its inlet is not lower in elevation than the bottom of the existing inside ditch. Culvert relief dips will be constructed with an outslope gradient of 3-10% across the road. The width of these dips will be at least as wide as the diameter of the target culvert. The finished sides of the dips will be at a stable angle that will not exceed a 50% gradient. The depth of culvert relief dips will be dictated by their width, outslope gradient, and sideslope gradient. All disturbed areas will be seeded and mulched.

Project Details Page 3 of 5

Broadbase Dips

Installation: Construct a broadbase dip where the Road Log and Project Drawings specify to Install

Broadbased Dip. Broadbase dips will be constructed to manage surface water drainage along segments of roads that lack inside road ditches while the road is in storage. No additional aggregate or stone will be hauled in for broadbase dip construction; all such materials noted in the typical detail for broadbase dips

(found in Project Drawings) are either available on site or will not be required. Where road surface gravel exists within the construction area for broadbase dips, it will be scraped off and stock-piled during construction and ultimately, placed as the armoring layer (aggregate base) in the completed dips as depicted in typical detail found in Project Drawings. The finished outslope gradient at the deepest part of the broadbase dip (cross-section D in the typical detail for broadbase dips) should be at least 5% to meet the road storage prescription. All disturbed areas will be seeded and mulched.

Improvement: Reshape existing broadbase dip where the Road Log and Project Drawings specify to Improve

Broadbased Dip. Reshaping is needed primarily to accentuate the outslope gradient in the deepest section of the broadbase dip (cross-section D in the typical detail for broadbase dips) to meet the road storage prescription; the finished outslope gradient should be at least 5% at this location. Otherwise, improvements to existing broadbase dips should result in a finished product that resembles the typical detail for broadbase dips found in Project Drawings. No additional aggregate or stone will be hauled in for broadbase dip improvements; all such materials noted in the typical detail for broadbase dips are either available on site or will not be required. Where gravel exists on road surfaces that will be disturbed during broadbase dip improvements, the gravel will be scraped off and stock-piled during improvement activity. Ultimately, this gravel material will be replaced as the armoring layer (aggregate base) in the completed dips as depicted in typical detail found in Project Drawings. All disturbed areas will be seeded and mulched.

Armored Overflow Spillway

Construct an armored overflow spillway at the locations indicated in the Road Log and Project Drawings.

Armored overflow spillways will be constructed across the road, down the fill slope, and back into the stream channel below the stream crossing culvert as shown in the Armored Overflow Spillway Typical (see Project

Drawings). These spillways will serve as the alternate channel for target streams to flow across the road prism in the event that the existing stream crossing culvert should plug or otherwise fail while the road is in storage. Armored overflow spillways are not intended to intercept stream water as long as existing stream crossing culverts are functioning properly.

Armored overflow spillways will be positioned close enough to the target streams to best serve their intended purpose yet be offset enough from the existing stream crossing culverts to avoid undermining the stability of these culverts. These spillways will be constructed so that the bottom of the inlet to the spillway channel is no higher in elevation than the top of the existing stream crossing culvert. The width of the spillway channel will be similar to the width of the existing stream channel above the culvert. The gradient of the spillway channel will be between 3-10% across the road. The finished sides of the spillway channel will be at a stable angle that will not exceed a 50% gradient. The depth of the spillway channel will be dictated by its width, outslope gradient, and sideslope gradient. All disturbed areas will be seeded and mulched.

Where road surface gravel exists in the areas to be excavated, it will be scraped off and stock-piled during construction of the armored overflow spillways. Ultimately, stock-piled gravel may be redistributed on finished surfaces to help armor against erosion. Spoil material produced during construction of the spillway channel will be used first to plug the inside ditch on the downslope side of the spillway channel, and

Project Details Page 4 of 5 secondarily along the downslope side of the spillway channel as it crosses the existing road. The entire overflow spillway channel will be armored with class 4 riprap but this material must be keyed riprap where the constructed channel descends the road fill slope. All disturbed areas will be seeded and mulched.

251- RIPRAP

251.04 Placed Riprap

Barrier Rocks

Boulders will be placed in the locations identified in the Road Logs to help prevent motor vehicle access to roads being treated under this contract. Boulder placement may be directed by the designated contract administrator. Boulders will be approximately 4’ median diameter, be partially buried to inhibit their movement, and be positioned to effectively restrict motor vehicle access (including ATVs). Native rocks may be approved for use if they are available on site and occur within the typical disturbance perimeter of other actions required by this contract.

251.05 Keyed Riprap

Class 4 riprap will be used to stabilize areas requiring keyed riprap. The contract administrator may approve the use of native rock sources if they are available on site and occur within the typical disturbance perimeter of other actions required by this contract.

625 – SEEDING AND MULCHING

625.03 Seeding Season.

Replace with:

Application of seed and mulch will be completed on disturbed areas within seven days of the disturbance.

The seeding season will generally occur between April 15 and October 15.

Project Details Page 5 of 5

625.07 Application Methods for Seed

(a) Dry Method

Seed mixture and application rates are as follows:

SPECIES APPLICATION RATE

Annual Ryegrass (Lolium multiflorum) 20 pounds per acre

Red Fescue (Festuca rubra) 25 pounds per acre

Canada Wild Rye (Elymus canadensis) 6 pounds per acre

Tioga Deer Tongue (Panicum clandestinum) 4 pounds per acre

Partridge Pea (Chamaecrista nictitans or fasciculata) 1 pounds per acre

(b) Hydraulic Method

All rates of application are the same as for the Dry Method.

Add the seed to the water slurry no more than 30 minutes before application. Areas inaccessible to seeding equipment shall be mulched by hand.

625.08 Application Methods for Mulch

(a) Dry Method.

Mulch shall be straw applied at the rate of 3,000 pounds/ac.

(b) Hydraulic Method.

Mulch shall be wood cellulose fiber applied at the rate of 1,500 pounds net dry weight/ac.

If the hydraulic method will be used to apply mulch, straw mulch will be required at the rate of

3,000 pounds/ac for the area within 20 feet on either side of stream channels at stream crossings and channel restoration sites.