B08_17 - CHOH Paw Paw Draft EA 508_0001.pdf

National Park Service U.S. Department of the Interior

Chesapeake and Ohio Canal National Historical Park Maryland

Improve Visitor Safety and Mitigate Rockfall Hazards in the Paw Paw Tunnel Hollow

Chesapeake & Ohio Canal National Historical Park

Environmental Assessment June 2020

Estimated Total Costs Associated with Background Research, Resource Surveys, and Developing and Producing this EA: $50,000

Improve Visitor Safety and Mitigate Rockfall Hazards in the Paw Paw Tunnel Hollow

[PAGE INTENTIONALLY LEFT BLANK]

i

Table of Contents

PURPOSE AND NEED

Background And Project Area

Issues And Impact Topics Retained For Analysis

Issues Dismissed From Further Analysis

ALTERNATIVES

No Action Alternative

Action Alternative: Stabilize Tunnel Hollow and Remove Spoils (NPS Preferred)

Mitigation Measures

AFFECTED ENVIRONMENT AND ENVIRONMENTAL CONSEQUENCES

Visitor Use, Experience, and Safety

Impacts of No Action Alternative

Impacts of Action Alternative (NPS Preferred)

Historic Structures

Impacts of No Action Alternative

Impacts of Action Alternative (NPS Preferred)

Archeology

Impacts of No Action Alternative

Impacts of Action Alternative (NPS Preferred)

Vegetation, Wildlife, and Special Status Species

Impacts of No Action Alternative

Impacts of Action Alternative (NPS Preferred)

Cultural Landscape

Impacts of No Action Alternative

Impacts of Action Alternative (NPS Preferred)

Cumulative Impacts

No Action Alternative

Action Alternative (NPS Preferred)

Conclusions

CONSULTATION AND COORDINATION

Agency Scoping

References

Appendix I: United States Fish and Wildlife Service Consultation Letter, Official Species List, and Determination of No Adverse Effect

Appendix II: Maryland Department of Natural Resources Consultation Letter ii

Appendix III: Maryland Historical Trust Consultation Letter and Assessment of Effect Report

FIGURES

Figure 1: Project area Figure 2: Paw Paw Hollow Figure 3: Action Alternative, Options 1, 2, and 3 for accessing the Paw Paw Tunnel Hollow Figure 4: Proposed spoil area Figure 5: Proposed staging area and Paw Paw Campground parking lot expansion and entrance road spoil area Figure 6: Rockfall Hazard Analysis of the Paw Paw Tunnel Hollow produced by Terracon Inc Figure 7: Paw Paw Hollow cultural resources Figure 8: Tunnel Hill Trail cultural resources Figure 9: The Paw Paw Tunnel Hollow, as seen from the North Portal of the Paw Paw Tunnel Figure 10: Undated picture of excursion trip on the Oak Spring at the north portal of the Paw Paw Tunnel.

Figure 11: Rock bolts in the Tunnel Hollow from the 2018 stabilization

PURPOSE AND NEED

The National Park Service (NPS) proposes to mitigate safety concerns associated with rockslides at the downstream entry of the Paw Paw Tunnel. The Paw Paw Tunnel is in a remote area of Allegany County in an area prone to rockslides. A towpath closure in the tunnel or areas immediately upstream or downstream of the tunnel requires a lengthy and strenuous detour over a mountain. The tunnel is the only emergency access route to the towpath on the downstream end of the tunnel. The tunnel also has historical significance as one of the most significant works of the Chesapeake and Ohio Canal, and typically receives more than 30,000 visitors each year.

The purpose of this project is to remove debris from the canal prism deposited in a 2016 rockslide and to stabilize the rock face adjacent to the canal for 1,000 feet north of the Paw Paw Tunnel. The project would also replace in-kind the wooden boardwalk that serves as the towpath for 750 feet of this stretch.

This project is needed to improve visitor safety and to prevent disruptions to towpath continuity that may result from future landslides. This project would also allow the park to address visitor safety and access issues at the Paw Paw Campground parking lot and on its entrance road. The campground parking lot is not currently large enough to accommodate the number of visitors to the area; when the existing parking lot fills, visitors park along State Route 51, creating a safety hazard. This project would provide the opportunity to use removed rock material to expand the existing parking lot and to widen the entrance ramp off of State Route 51 from one lane to two lanes, thus reducing the possibility of collision between cars entering and exiting the campground.

This EA has been prepared in accordance with the National Environmental Policy Act (NEPA) of 1969, as amended, and implementing regulations, 40 Code of Federal Regulations (CFR) Parts 1500-1508, NPS Director’s Order 12: Conservation Planning, Environmental Impact Analysis, and Decision-making, and the accompanying NEPA Handbook. Compliance with Section 106 of the National Historic Preservation Act of 1966 (NHPA), as amended, is being conducted concurrently with the NEPA process.

BACKGROUND AND PROJECT AREA

The project area stretches from a proposed spoil location at the end of Outdoor Club Road at mile marker 153.5, to the proposed staging area at the parking lot of the Paw Paw Campground located off State Route 51 at mile marker 156 (Figure 1). Most of the project would be focused in the Tunnel Hollow where the rock stabilization activities would take place (Figure 2) but would also include the area in the immediate vicinity of the towpath along the entire length. The project area also includes portions of Tunnel Hill Road and Tunnel Hill Trail. Tunnel Hill Road runs from Malcolm Road, over Tunnel Hill, intersects with Tunnel Hill Trail, and continues south into the Maryland State lands of the Paw Paw Bends. Tunnel Hill Trail begins near the southern portal of the Paw Paw Tunnel, climbs Tunnel Hill, intersects Tunnel Hill Road at the summit and continues down the north side of Tunnel Hill to the towpath in the Tunnel Hollow. The main historical features in the project area are the tunnel itself, the cuts to the north and south, and the structures in the Tunnel Hollow Complex in the hill cut 2,000 ft north of the downstream tunnel portal of Paw Paw Tunnel.

The Paw Paw Tunnel was constructed by the C&O Canal Company to cut across the Paw Paw bends of the Potomac River, thus reducing the six miles of canal necessary to follow the river around the four meanders of the bends to one and a half miles. It is located between mile markers 155 and 156 on the canal near the town of Paw Paw, West Virginia; the tunnel, the town, and the bends all derive their name from the paw paw tree, which grows abundantly in this area. Construction on the tunnel began in 1836 and continued until 1842 when funding for the project was exhausted; construction eventually resumed in 1847 and the tunnel was finally completed in 1850. The project was delayed by a shortage of skilled laborers, strikes, the remoteness of the work area, frequent rockslides, and an underestimation of the time and money needed to complete the project which, unfortunately, coincided with financial issues within the company. The Paw Paw Tunnel remained an operational part of the canal until 1924 when the C&O Canal Company ceased commercial navigation.

Rockslides have been a documented problem in the Tunnel Hollow since construction began. The character of the rock is such that exposure to weathering leads to fracturing and rockfall. Landslides in the cuts have been noted by NPS throughout the history of the park with major slides occurring in 1968, 1969, 1974, 1975, 1976, 1977, 1997, 2013, and 2016. Most of these occurred on the western slope of the northern cut. NPS has made previous attempts to address these hazards, notably in 1956, 1979, the mid 1990s, and 2018. In 1956, portions of the tunnel vault brick work, the towpath, and the towpath boardwalk were repaired and rockfall debris was removed from the canal. In 1979, the tunnel portals were cleared of vegetation and repointed, and rockfall debris was removed from the canal. In 2018, scaling was used to remove unstable rock from the eastern slope of the north cut, the scaled material was placed against the side of the canal. Rock bolts and shear blocks were installed to prevent further destabilization, and draped mesh was placed over select areas to catch further rockfall.

Environmental Assessment

Figure 1: Project area.

Figure 2: Paw Paw Hollow.

ISSUES AND IMPACT TOPICS RETAINED FOR ANALYSIS

This section describes project issues or concerns identified during scoping that were determined by the project team to warrant a more detailed analysis.

Visitor Use, Experience, and Safety – This project would necessitate a visitor detour of approximately

0.65 miles through steep, arduous, and isolated trails. The windy detour trail would consist of 1.45 miles with an elevation gain of over 400’. This detour would be in place for the duration of the project, which is expected to last 12-18 months. This section of the towpath is also part of the Potomac Heritage National Scenic Trail, the Greater Allegheny Passage, and the American Discovery Trail. This project may result in temporary visitor impact by forcing a reroute but would preserve trail continuity by addressing safety issues in the Tunnel Hollow chokepoint; currently, this is the only bicycle passage through the mountains of Western Maryland.

Historic Structures – There are numerous historic structures within the project area, and all are associated with the C&O Canal. The boardwalk is a 1970s re-creation of the boardwalk that was historically located in the same location and has been repaired and replaced in several sections due to damage from rockfall and normal degradation. This project proposes to replace the boardwalk with similar materials to eliminate safety hazards while maintaining the cultural landscape.

Archeology – This area is rich in prehistoric and historic archeological resources. A historic archeological site associated with the construction of the tunnel and the Paw Paw Superintendent’s House is located near the proposed expansion of the Paw Paw Campground Parking Lot. The entirety of the Tunnel Hollow is a historic archeological site and the canal and towpath likely contain archeological resources. An additional archeological site was discovered in May 2020; however, the site is outside of the project limits and will not be disturbed as part of this project.

Cultural Landscape – The cultural landscape in the project area has not been evaluated for National Register eligibility. However, the Paw Paw Tunnel and Tunnel Hollow offer a unique viewscape that has been a popular attraction since construction was completed. Additonally, a significant number of features remain on the landscape from the construction of era of Tunnel Hollow.

Vegetation, Wildlife, and Special Status Species – The project area is within a globally rare Appalachian shale barren community, with steep, shale slopes. NPS conducted surveys of the project site for State-listed rare plants between summer 2019 and spring 2020. Seven rare, threatened, or endangered (RTE) plant species within the project area were identified.

ISSUES DISMISSED FROM FURTHER ANALYSIS

This section provides brief descriptions of issues and concerns identified during scoping that were determined to not warrant further consideration, as well as a brief justification for the dismissal of each issue.

Geologic Resources – The proposed scaling would expedite the natural erosive forces currently acting on this stone-faced cliff. However, being carved out when the Canal was established, this stone face is not natural. In addition, the scaling process would be removing rock that would fall from the cliff face naturally, and as a result, geologic resources were not an issue covered under this EA.

Wetlands – Wetlands found within the canal prism would be temporarily impacted during the scaling operations as well as the temporary storage of the overburden materials. Due to the contracting mechanism for this project, the final design has not been completed and the extent of the impact to wetlands is not yet known. As more information becomes available, NPS will continue to consult with Maryland Department of the Environment (MDE) and the United States Army Corps of Engineers (USACE) to conduct wetland delineations and obtain appropriate permits. Practical steps to avoid and minimize potential adverse impacts on wetlands would be taken and wetlands damaged by the actions

ALTERNATIVES

This EA documents the analysis of environmental consequences of two alternatives: the no-action alternative and the proposed action/preferred alternative. Under the action alternative are three options for access to the project area. The elements of these alternatives are described in detail herein. Impacts associated with the actions proposed under each alternative are outlined in the “Affected Environment and Environmental Consequences” section of the EA.

NO ACTION ALTERNATIVE

Under the No Action Alternative, the rockfall from the 2016 landslide would be left in place within the canal prism. NPS would not undertake rock stabilization efforts and the risk of landslides and rockfall would continue to be a threat to visitors as the exposed rock continued to weather and degrade. Since the canal, which acts as a rock catchment area, is currently filled, future landslides and rockfall will likely impact the existing wooden boardwalk where visitors are most likely to be. It is possible that a landslide could destroy a portion of the boardwalk, breaking towpath continuity. Future landslides would be removed as they occurred, if extent of rock material was minor, but mobilization and funding for removal of large rock debris would likely be a multiyear process. The boardwalk would continue to undergo regular maintenance and repair/rehabilitation of the boardwalk would be addressed in the CHOH 5 year plan and addressed in a future project.

ACTION ALTERNATIVE: STABILIZE TUNNEL HOLLOW AND REMOVE SPOILS (NPS

PREFERRED)

Under this Alternative, a staging area would be established at the Paw Paw Campground, the wooden boardwalk would be replaced in-kind, the cliff faces in the Tunnel Hollow would be stabilized, and the 1,600 cubic yards of rockfall from 2016 would be removed along with all material produced by the proposed stabilization efforts of this project.

The proposed staging area in the Paw Paw campground would be based around the existing parking lot and would likely involve an expansion of the parking lot to the east towards State Route 51. The current parking lot and area noted for parking lot expansion sit on a historic archeological site (18AG255) associated with the construction of the tunnel. Design and construction of the parking lot would be guided and monitored by an NPS archeologist.

The 750 foot long wooden boardwalk in the Tunnel Hollow was constructed in the 1970s and has degraded to the point of being a safety concern. The boardwalk would be removed during the initial phases of the proposed project and replaced in-kind when the rock stabilization and removal portions of the project have been completed.

Rock stabilization would include scaling, rock bolts, shear blocks, pinned mesh, and rock drains as needed. Scaling, rock bolts, and rock drains have been used by NPS in this area since the 1970s. Scaling involves manually or mechanically removing loose or fractured rock from the cliff faces until reaching a stable rock surface. Rock bolting involves drilling holes 10 to 15 feet deep into the rock face and inserting steel rods to restrain unstable rock mass. Shear blocks also involve drilling deep holes in the rock face;

however, concrete blocks are attached to the ends of these bolts. Shear blocks are placed under unstable rock ledges to provide support. Pinned mesh is a combination of anchors and steel rockfall mesh; it is used to catch and retain rockfall against the face of the slope the slope instead of letting it fall or bounce away from the slope into areas that are more likely to have visitor traffic. Rock drains are used to relieve groundwater pressure between layers of rock and reduce the weathering of the rock from freeze-thaw cycles by drilling holes into the rockface and installing PVC pipe to drain water from areas with noted water infiltration.

Rockfall hazards would be addressed in priority order according to the 2019 geotechnical report. Draped mesh installed during the 2017-2019 emergency stabilization project would be removed. The slope under the removed mesh would be scaled and pinned mesh would only be added to the upper portions of the cliff where the rock planes lie perpendicular to the rock face. Rock bolts would be ineffective in these areas which experience differential weathering among the many different exposed rock planes.

This project also proposes to rehabilitate concrete drainage channels above the north portal of the Paw Paw Tunnel. These channels were installed by NPS in the 1970s and serve to drain surface water from the areas above the tunnel. Currently, the channels are silted in and damaged and do not function.

Three Options have been identified for the removal and spoiling of the rockfall material. Option 1 is preferred by NPS. It is also possible that a combination of these options would be needed to complete the proposed project (Figure 3). Spoiled material may be used in future projects to repave roads in the area.

Option 1: Under this option, rockfall material would be transported along the canal prism until out of the deep cut and then along the towpath downstream to an existing causeway over the canal between Culvert 210 and the southernmost end of Outdoor Club Road. The rockfall would be spoiled to the north and south of existing spoil piles which contain material removed from Tunnel Hollow in the 1970s and again in the 1990s, now overgrown with vegetation (Figure 4). This spoil may also be used to realign Twigg Run with the historic drainage which was excavated in the 1830s to redirect Twigg Run into Gross Run so that both streams would pass under the canal at Culvert 210, saving the expense of an additional culvert. If Outdoor Club Road is used to access the proposed spoil area for ingress or egress, a temporary stream crossing will be necessary to cross Gross Run.

Option 2: Under this option, rockfall material would be transported along the canal prism through the Paw Paw Tunnel and then along the towpath to the Paw Paw Campground. The material would be spoiled along the western edge of the campground entrance road where it meets State Route 51. Spoiling the material here would facilitate the expansion of the entrance road to two lanes, which would mitigate a long-standing safety issue of narrow access to and from the heavily used state route. Additional material may be spoiled on or around the existing parking lot or proposed staging area to permanently improve and expand the existing parking lot which would alleviate overcrowding seen in the existing parking lot (Figure 5).

Option 3: Under this option, rockfall material would be transported along Tunnel Hill Trail and Tunnel Hill Road. If Allegany County permits, as portions of the trail and road are on state land, the material would be spoiled on the trail and road to repair and improve the surface. Additional material may be spoiled on nearby roads managed by Allegany County in the Green Ridge State Forest. In order to use this route, Tunnel Hill Trail and Tunnel Hill Road would have to be widened in some areas to better accommodate vehicles. Excess rock material beyond that used on the Tunnel Hill Trail and Road would be used to expand the existing parking lot and entrance road at the Paw Paw Campground. The Paw Paw Campground parking lot is not large enough to accommodate the number of visitors to the area; when the existing parking lot fills, visitors park along State Route 51, creating a safety hazard. The single lane access road to the campground from State Route 51 is another safety hazard that this project is intended to address by expanding the road to two lanes, thus reducing the possibility of collision between cars entering and exiting the campground. Under this Option, we would plan to address these safety issues by using the removed rock material to expand the parking lot and widen the entrance ramp.

Figure 3: Action Alternative, Options 1, 2, and 3 for accessing the Paw Paw Tunnel Hollow.

would be restored as soon as is possible after the actions have occurred. All work that may affect wetlands in the proposed project would be done in accordance with Directors Order #77-1: Wetland Protection (DO #77-1). NPS will consult with NPS wetland scientists regarding whether an exception from the reporting requirements under DO #77-1 is appropriate for the proposed project or if the project will require a Wetland Statement of Findings and mitigation. Because wetland impacts are expected to be minimal and any impacts to wetlands would be mitigated after work is complete, this topic area is excluded from further analysis. If it is determined that a Wetlands Statement of Findings is necessary, it will be completed and appended to this Environmental Assessment.

Floodplains – The proposed spoil areas and Paw Paw Campground parking lot expansion area are within the FEMA 100-year floodplain. Any actions in these areas that would result in permanent changes to the floodplain must be permitted through MDE and USACE. NPS has begun coordinating with MDE to avoid or mitigate any impacts to these areas. Final determination of effects from MDE and USACE await the NPS permit application which will be based on final design specifications when they become available. NPS does not anticipate that the proposed project will significantly alter the 100-year floodplain in this area. All work that may affect floodplains in the proposed project would be done in accordance with Directors Order #77-2: Floodplain Management (DO #77-2).

The proposed parking lot expansion covers a small area and would not require a large amount of material.

The proposed spoil location in the Paw Paw Campground is along the raised entrance road and should not affect river flow during times of flood. The volume of spoil would also be small relative to the size of the floodplain. The proposed spoil location near Culvert 210 is adjacent to the existing spoil pile. The new material would be deposited in a narrow and tall spoil pile in the shadow of the existing spoil to avoid any impacts to the river flow during times of flood, the volume of spoil is also very small relative to the size of the floodplain. If it is determined that the rockfall material should not be spoiled at the proposed locations, the material will be spoiled on non-NPS land in accordance with local, State, and Federal regulation. Because this project will not significantly affect the floodplain, this topic area is excluded from further analysis.

Figure 4: Proposed spoil area.

Figure 5: Proposed staging area and Paw Paw Campground parking lot expansion and entrance road spoil area.

Environmental Assessment

MITIGATION MEASURES

Mitigation, according to NEPA (40 CFR 1508.20), includes the avoidance or minimization of impacts to resources. To minimize impacts related to the proposed alternative, the NPS would implement mitigation measures when and wherever feasible. Mitigation measures would include, but would not be limited to, the measures listed below:

Historic Structures Mitigations

The contractor would be required to protect all historic structures in the project area. This would likely be accomplished by identifying historic structures, applying vibration monitors adjacent to vehicular paths, and maintaining low speeds while traveling along the towpath.

High visibility material may be used to temporarily identify historic structures that are close to the proposed paths of travel and traffic delineators or boundary markers may be used to ensure vehicles do not stray from designated paths of travel.

Gravel, geotextile, timber mats, or steel plates would be placed, as needed, over sensitive historic structures such as historic retaining walls, Culvert 210, and the wasteweir to more evenly distribute the weight of passing vehicles. If necessary, temporary bridges would be constructed over the structures to avoid damage.

Cribbing or additional stabilization could be placed in locks if it is determined that the weight of heavy equipment may affect the lock walls.

Vibration monitors and structural deformation monitors would be placed in the Paw Paw Tunnel.

If the passage of vehicles creates unacceptable vibrations levels or if the structural deformation monitors indicate strain or damage, additional timber mats or other structural supports would be installed before work could continue. Monitoring devices will be mounted on mortar joints, not on masonry.

Unless a means of ingress and egress can be identified that does not cause excessive vibrations under Action Alternative Option 2, vehicular access to the Paw Paw Tunnel would be limited to smaller equipment and only when necessary to reach the project site.

Archeological Resources Mitigations

Any ground disturbance related to the parking lot expansion in the Paw Paw campground would be limited to the top six inches of soil, leaving a buffer of six inches before archeological features would be encountered. A CHOH archeologist would be present to monitor during any activities involving ground disturbance.

Gravel and geotextile would be required in the staging area to distribute the weight of heavy equipment.

Cultural Landscape Mitigations

The exterior portions of rock bolts and pinned mesh would be colored to match the surrounding rock face, if possible.

The ends of the rock drains will be cut flush with the rock surface and would be painted to match the surrounding rock face.

The existing draped mesh would be removed. Pinned mesh would be added at various locations along the slope but at higher elevations that would be less impactful to the cultural landscape.

Contractor would be encouraged to develop designs to make shear blocks less apparent. Possible techniques may include coloring the concrete to match the surrounding rock face or shaping the concrete to appear more similar to the surrounding rock face.

Vegetation, Wildlife, and Special Status Species Mitigations

• No tree cutting would be allowed between June 1st and July 31st to protect tree-roosting bats.

• Travel restrictions for vehicles through the Paw Paw Tunnel will be set in coordination with Maryland Department of Natural Resources in an effort to protect any hibernating bats that may use the tunnel.

• RTE populations in the project area would be marked with high visibility flagging or paint so that the contractor can avoid impacts when possible. RTE populations on the cliff face will not be marked due to the danger of traversing the steep and unstable slope.

AFFECTED ENVIRONMENT AND ENVIRONMENTAL

CONSEQUENCES

This chapter describes current environmental conditions in and surrounding the project area. These conditions serve as a baseline for understanding the resources that could be impacted by implementing the project. In addition, this chapter would include an analysis of the environmental consequences of each alternative.

VISITOR USE, EXPERIENCE, AND SAFETY

The project area is located between mile 154.2 and 156.14 of the C&O Canal towpath and contains many visitor attractions including the 5-acre Paw Paw Campground, the Paw Paw Superintendent’s house, the Paw Paw Tunnel, Locks 62, 63 1/3, 64 2/3, and 66, a wasteweir, Culvert 210, 3 miles of the towpath, the entirety of the Tunnel Hill Trail, and a 3-acre area of woodland north of Culvert 210. This area is owned by the Chesapeake and Ohio Canal NHP except for a portion of the Tunnel Hill Trail, which is owned by Allegany County and managed by Maryland Department of Natural Resources. A vehicle traffic counter at the entrance to the Paw Paw Campground estimates approximately 30,000 visitors per year. However, this estimate does not account for hikers and bikers traveling up or down the towpath from other areas.

The Paw Paw Tunnel is an impressive engineering feat unique to the canal, the Paw Paw Tunnel Hollow Complex offers a completely manufactured historical landscape, and the lift locks in this area were constructed differently than many others on the canal.

A 2019 inspection of the Paw Paw Tunnel Hollow (Tunnel Hollow) by Terracon Consultants, Inc.

revealed rockfall hazards throughout the deep cut on both the east and west sides of the canal prism. The inspectors divided the Hollow into zones and assigned each zone a risk score which was based on a number of factors including slope height, available catchment area, structural condition, volume of material, history of rockfall, and water activity. This analysis revealed moderate visitor safety risks in all of the zones except for the areas that had been stabilized during previous projects (Figure 6).

Figure 6: Rockfall Hazard Analysis of the Paw Paw Tunnel Hollow produced by Terracon Inc.

Impacts of No Action Alternative

Under this alternative, the current management of the area would continue. The rockfall from the 2016 landslide and the spoil from the 2018 scaling would remain, and NPS would not perform rockfall mitigation efforts in the deep cut of the Tunnel Hollow. The wooden boardwalk would continue to undergo regular maintenance and would eventually be replaced as part of the CHOH cyclic maintenance plan. If landslides continue, the towpath in the Tunnel Hollow may eventually need to be closed to mitigate safety concerns. Visitor traffic would be routed over the mountain along the 1.45-mile Tunnel Hill Trail. The Tunnel Hill trail is longer, steeper, and more rugged than the towpath through the tunnel and would not provide an equivalent visitor experience. If the Tunnel Hollow were closed to visitors, most of the tunnel would remain open but visitors would no longer be able to travel through to the north portal. Visitors would also be unable to see the deep cut of the Tunnel Hollow Complex which is unique on the canal. It is likely that visitation to this area would decrease if the north portal of the tunnel and towpath were closed.

Impacts of Action Alternative (NPS Preferred)

The the Paw Paw Tunnel and 3 miles of towpath and the associated canal structures would be closed to visitors for the duration of the project, which is expected to last from 12-18 months. The stabilization of the rockface would protect visitors and allow this section of the towpath to remain open. The 750 foot boardwalk would be reconstructed after the rockfall mitigation portion of the project was completed. The current boardwalk is aging, and its replacement would increase visitor safety and provide a more enjoyable visitor experience.

Option 1:

Under this option, the towpath closure would extend an additional 2 miles from the end of the Tunnel Hill Trail to the causeway north of Culvert 210. This closure would last for the duration of the project but would allow material to be safely transported along the towpath to the proposed spoil location.

Option 2:

Under this option, the Paw Paw Tunnel Campground and parking lot would be closed for the duration of the project, an estimated 12-18 months. Rockfall material would be spoiled along the Paw Paw Campground entrance road, widening it to two lanes. This would improve visitor safety for vehicles entering and leaving the Paw Paw Campground. Additional rock material would be placed directly adjacent to the existing Campground parking lot. The proposed parking lot expansion for the staging area in the Paw Paw Campground would remain to increase available visitor parking after the project has been completed.

Option 3:

Under this option, rockfall material would be spoiled on Tunnel Hill Road and Tunnel Hill Trail, improving visitor access along the Tunnel Hill Trail. This improvement would also improve emergency access to the Paw Paw Tunnel Hollow, which is difficult to reach by vehicle.

HISTORIC STRUCTURES

The project area encompasses the Paw Paw Campground, the Paw Paw Tunnel, and the Paw Paw Tunnel Hollow Complex, the proposed spoil area, and the area in the immediate vicinity of the towpath from the northern portal of the Paw Paw Tunnel 1.5 miles north along the towpath to a rubble causeway built across the canal north of Culvert 210. The entire project area is an historically significant and modified landscape associated with the Chesapeake and Ohio Canal. The project area also includes a portion of Tunnel Hill Road, between its beginning at Malcolm Road and its intersection with Tunnel Hill Trail at the summit of Tunnel Hill. Tunnel Hill Road continues out of the project area and into the Paw Paw bends; the project area follows Tunnel Hill Trail from the intersection with Tunnel Hill Road to the towpath on the towpath in the Tunnel Hollow. The Hollow was excavated between 1836 and 1850 and contains canal infrastructure as well as the remains of structures associated with canal management and operations. The base of the Hollow is narrow and much of the available space is taken by the canal and towpath for which it was excavated. The remaining space was used for various maintenance, storage, and housing structures. The Tunnel Hollow Complex operated as a part of the canal from its completion in 1850 until the cessation of commercial navigation in this area in 1924. There are numerous historic structures listed on the NRHP that fall within the APE:

Structure LCS Number Mile Marker Canal Prism 45702 153.0 – 154.0

Towpath 45703 153.0 – 154.0 Culvert 210 11737 153.46 Canal Prism 45704 154.0 – 155.0

Towpath 45705 154.0 – 155.0 Bypass Flume for Lock 62 12885 154.16

Lock 62 11738 154.17 Lockhouse Foundation at Lock 62 11739 154.18 Boat Basin at Sandy Flat Hollow 45638 154.21

Spillway and wasteweir 11740 154.29 Bypass flume for Lock 63 1/3 12866 154.48

Lock 63 1/3 11741 154.49 Lock 64 2/3 11742 154.61

Retaining Wall Ruins at Lock 64 2/3 45640 154.61 Bypass Flume for Lock 64 2/3 12877 154.62

Ruins at Lock 64 2/3 45641 154.63 Bypass Flume for Lock 66 17223 154.70

Carpenter’s Shop Foundation at Lock 66 11744 154.71 Lock 66 45642 154.72

Towpath Boardwalk (Non-Contributing) 45631 154.95 Canal Prism 45706 155.0 – 156.0

Towpath 45707 155.0 – 156.0 Downstream Portal of Paw Paw Tunnel 45630 155.20

Paw Paw Tunnel 45629 155.70 Upstream Portal of Paw Paw Tunnel 45627 155.78

Canal Prism 45708 156.0 – 157.0 Towpath 45709 156.0 – 157.0

Paw Paw Superintendent’s House 17224 156.16

Four additional historic structures have been identified on the Tunnel Hill Trail: a dry laid stone retaining wall, two collapsed spring houses, and the historic road that the trail follows.

The canal prism served as a waterway for canal boats which were specially designed to haul freight between Cumberland and Georgetown, the western and eastern termini of the C&O Canal. Along most of the canal, the prism was constructed to be just wide enough to allow two canal boats to pass. However, in the Tunnel Hollow, the canal prism is only wide enough to allow one-way traffic due to the difficulty and expense of excavating the tunnel and cut. The prism runs the length of the project area and is no longer actively maintained. The original clay liner which waterproofed the prism has been eroded away and pierced by vegetation in many areas. It is unlikely that a clay liner was needed in the areas where the canal was cut into the rock. Natural seeps and springs in the area drain into the prism resulting in 1 to 2 feet of standing water. The water level has increased in recent years as drainage along the canal has been blocked by a landslide.

The towpath originally served as a pathway for the mules which towed the canal boats during canal operations. The towpath runs the length of the project area and is a defining feature of the park. It was originally built from spoil from the canal prism excavation and crushed local stone. However, the towpath in this area has been repaired or rebuilt many times and, except in the areas where it has been carved out of bedrock or consists of masonry, it likely lacks historic integrity.

The Paw Paw Superintendent’s House was built in 1850 and served as the residence of the section superintendent from the construction of the canal until the cessation of commercial navigation on the canal in 1924. It is a two-story, L-shaped frame structure with a brick foundation.

The Paw Paw Tunnel is 3,118 feet long and runs roughly north-to-south, with the northern portal facing downstream. Masonry portals support each entrance while the tunnel vault is lined in brick. The towpath lies on an intentionally unexcavated stone bench faced with brick and timber. To the north and south of the tunnel are long cuts which were made to accommodate the canal where the surface elevation was not yet high enough to necessitate tunneling. The northern cut is approximately 1,000 feet long while the southern cut is about 200 feet long; the depths of the cuts vary, but in some areas are over 100 feet deep.

Four vertical shafts were sunk to aid in the excavation of the tunnel and to provide ventilation for the tunnel miners. The shafts are located, two each, in the bottom of each of the two ravines above the tunnel, there being the shortest vertical distances to the tunnel. After the tunnel vault had been completed, the shafts were left empty and capped with brick, stone, and clay.

The boardwalk is a 750 foot long timber framed portion of the towpath running from the end of the Paw Paw Tunnel towpath, which sits on a ledge of unexcavated bedrock, north to the resumption of the earth and rubble towpath. During canal operations, a wooden boardwalk existed in the same footprint as the current boardwalk and served as the towpath. At some time during NPS ownership of the canal, the remnants of any extant boardwalk were removed and replaced by a causeway of fill and rockfall. In 1956, NPS removed the fill causeway and reconstructed the wooden boardwalk while performing repairs to the Paw Paw Tunnel. In 1976 and 1977, NPS removed 15,000 cubic yards of rockfall from the canal prism and again replaced the boardwalk. The boardwalk is listed as a non-contributing feature on the NRHP.

Lock 66 is a composite lift lock at mile 154.7 of the canal (Figure 7). Composite locks were the result of cost saving measures and differed in material and design from the other locks on the C&O Canal. The composite locks in the Tunnel Hollow were constructed with materials sourced from local quarries which produced stone inferior to the material typically used in locks. To further reduce costs, the facing of composite locks consisted of wood rather than stone. The contract for the construction of the locks in the Tunnel Hollow was awarded in 1837, but due to financial problems and the technical difficulty of excavating the tunnel and Hollow, the locks were not completed until 1850. The locks are approximately 100 feet long and have 15 foot chambers, which are the standard dimensions for lift locks on the canal.

The composite locks in the Tunnel Hollow are masonry and wood structures on wooden foundations laid on bedrock, Lock 62 is a masonry and wood structure, but the foundation upon which it rests is unknown.

However, due to the steep terrain and limited space, these locks lift the water level 10 feet, which is higher than the average lift of 8 feet across other canal locks. Lock 66 was constructed with red and grey sandstone from a quarry at Twigg Hollow north of Lock 61 and near the proposed spoil area, but the gate recesses were faced with concrete in 1910. The stone removed from the lock is piled on the river side of the towpath across from each lock gate. Currently, Lock 66 is in poor condition, with the wooden facing rotted away, leaving iron pins protruding from the stone walls. Portions of lock gate timbers and hardware can be found downstream, in the canal prism. A wooden footbridge has been constructed over the downstream end of the lock. The downstream river side wing wall of the lock interfaces with a 4 foot-high, 150 foot-long retaining wall, also constructed with red and grey sandstone, which supports the towpath. There is also a depression between the lock and the towpath where a snubbing post was once located.

Lock 64 2/3 is a composite lift lock at mile marker 154.6. This lock was constructed of the same materials and in a similar fashion to Lock 66. Originally, four locks were planned for the Tunnel Hollow. To save money, the canal company canceled plans for the construction of Lock 65 and increased the lift on Locks 63 1/3, 64 2/3, and 66 to compensate. The fractions in the designations for Locks 63 1/3 and 64 2/3 were incorporated to preserve the lock numbering system as the locks upstream of 66 had already been completed. The wooden facing has almost entirely rotted away, and a few boards hang from one of the iron supports in the stone wall. The chamber walls of the lock consist of gray and red sandstone from Twigg Hollow Quarry. The gate recesses were replaced with concrete in 1910 and the stone from the lock is piled on the river side of the towpath. A wooden foot bridge has been constructed over the downstream end of the lock. The downstream river side wing wall of the lock interfaces with a 4 foot-high, 100 foot-long retaining wall, also constructed with brown and grey sandstone, which supports the towpath. There is also a depression between the lock and the towpath where a snubbing post was once located.

A coursed rubble retaining wall is located on the river side of the towpath at the downstream end of Lock 64 2/3. The structure associated with the retaining wall has collapsed but the retaining wall is intact. It was labeled as Feature H in the 1976 archeological survey of the Tunnel Hollow. Feature H incorporates the retaining wall, two mounds of brick rubble, and some white granite support stones. Most likely, this was a log structure on sill stones with a brick chimney. The dates of construction, occupation, and demolition of this structure are unknown.

Lock 63 1/3 is a composite lift lock at mile marker 154.5. This lock was constructed at the same time and in a similar fashion to Locks 64 2/3 and 66 and provides 10 feet of lift. The coursed rubble walls of the chamber are constructed from white and grey sandstone from Twigg Hollow. Similar to the other locks in the Tunnel Hollow, the gate recesses were replaced with concrete in 1910 and the original stone is piled on the river side of the towpath. The wooden facing has completely degraded leaving only the iron support bars, and the walls of the chamber have cracked and bulged on the downstream inland side of the lock. The upstream river side wing wall has cracked away from the lock and is collapsing into the prism.

A wooden walkway has been constructed across the downstream end of the lock. The downstream river side wing wall of the lock interfaces with a 4 foot-high, 100 foot-long retaining wall, also constructed with white and grey sandstone, which supports the towpath. There is also a depression between the lock and the towpath where a snubbing post was once located. A masonry flanking wall extends from the upstream towpath wingwall, across the towpath to the base of the Tunnel Hollow slope.

A combination wasteweir and spillway is located at mile marker 154.1 near the downstream end of the Tunnel Hollow. A spillway is an area of the canal where the towpath has been lowered and hardened, providing an escape for floodwaters while preventing erosion. A wasteweir is a structure that controls the water level of the canal. In this wasteweir, water was kept in the canal with wooden boards fitted into masonry, and later, concrete slots. The boards could be removed or added as needed to alter the water level. The structure is 100 feet long, 16 feet wide, and was constructed in 1850 and consists of a wasteweir flanked by two spillways. The spillways and wasteweir feed into the same chamber which is lined in stone and concrete and built into a shale outcropping. At some time in the past, the spillways were filled in by towpath material, leaving only the flumes exposed. The wasteweir was constructed in this location to enable it to quickly drain floodwaters from the Sandy Flat Hollow drainage, to the west, in lieu of a culvert. The original construction was in coursed gray and red sandstone from the Twigg Hollow Quarry. The 3-gate, board insert, stone and concrete wasteweir was built into the center of the spillway in 1913.

Lock 62 is a composite lift lock at mile marker 154. The lock was constructed at the same time and in a similar manner to the locks in the Tunnel Hollow and provides 10 feet of lift. The lock chamber was constructed of gray and red sandstone from the Twigg Hollow quarry and was once face with wood. The wood has rotted away, leaving only the iron pins which once held the wood in place. The gate recesses were faced with concrete in 1910 and the facing below the lower recess is concrete. A wooden footbridge has been constructed over the upstream end of the lock. The downstream river side wing wall of the lock interfaces with a 4 foot-high, 100 foot-long retaining wall, also constructed with grey sandstone, which supports the towpath.

The concrete foundation attributed to the Lock 62 lockhouse is located at mile marker 154 on the river side of the towpath, across from Lock 62. The lock houses were built by the C&O Canal Company to house lock tenders who were responsible for operating their lock. The structure is 26 feet long and 16 feet wide, has 8-inch thick walls, and its long axis is aligned parallel to the towpath. On the towpath side of the structure there are four concrete posts which once supported a porch. At one time, this foundation supported a frame structure, but any remains have been removed.

Culvert 210 is located at mile marker 153.4 and was constructed in 1849 to allow the passage of Gross Creek. Culverts were constructed to allow minor streams and drainages to flow beneath the canal prism.

The barrel is made of brick with a 12 foot span and a 6 foot rise and has a 1 foot high parapet. The wing walls and parapet are constructed from red and grey sandstone; the berm side parapet is faced with concrete and intact, but the riverside parapet has collapsed, and bricks are eroding out of the vault. The poor condition of the riverside parapet was first noted in 1971.

Tunnel Hill Road is an unimproved road following its historic footprint over Tunnel Hill (Figure 8). The portion of the road within the project area stretches 3,000 feet from Malcolm Road to the intersection of Tunnel Hill Road and Tunnel Hill Trail. From this point, Tunnel Hill Trail would be used to access the Paw Paw Tunnel Hollow. The Trail stretches 4,300 feet long from the intersection with the towpath and its width varies between 7 and 14 feet. Both the road and the trail have existed since at least 1836 when construction began on the nearby tunnel, but it has been graded and improved many times and it is unclear whether it retains historic integrity. Portions of the road are in poor condition due to erosion and the portion nearest the Hollow, which consists of two narrow and steep switchbacks, has been undercut.

There is some evidence that, at one time, a dry laid stone retaining wall supported the downhill side of the road, which is now being undercut. Neither the Tunnel Hill Road nor the Tunnel Hill Trail are listed in the NRHP.

A dry laid stone wall was noted at a point approximately 2,700 feet downhill from the NPS gate at the intersection of Tunnel Hill Road and Tunnel Hill Trail. The 18 foot long wall is 4.5 feet from the edge of the road and was built as a retaining wall for the road. The road is 8.5 feet wide in this location and the land slopes steeply up north of the road and steeply down south of the road.

Two collapsed spring houses are located approximately 4,240 feet downhill from the NPS gated road entrance, between the last switchback on Tunnel Hill Road and the towpath. They are dry laid constructions of spoil from the tunnel excavation, and they are built into a large pile of spoils. They are approximately 15 feet apart and there is water flowing through each springhouse.

Historic structures within the APE would be unaffected. Regular maintenance would be performed on the boardwalk, but it would continue to decay as it is at the end of its structural life. The boardwalk would continue to be a safety hazard and would be vulnerable to future rockfalls and landslides. The boardwalk would continue to undergo regular maintenance and repair/rehabilitation of the boardwalk would be addressed in the CHOH 5 year plan and addressed in a future project.

Impacts of Action Alternative (NPS Preferred)

Under this Alternative, actions would be taken to avoid, minimize, and reduce impacts to historic structures within the APE. Heavy equipment would be transported into the project area by way of the Paw

Paw Tunnel which may damage the structure with vibrations, impacts, or exhaust fumes. Large equipment would be transported into the project area, where it would remain until the project ends, at which point it would be removed again through the Tunnel. Vibration monitoring equipment would be installed to ensure equipment transport does not cause adverse effects to the Tunnel. The boardwalk would be replaced with in-kind materials and within the same footprint of the current boardwalk. The canal prism would be restored as rock debris is removed.

Option 1:

Smaller heavy equipment, including dump trucks, would drive through the Tunnel to reach the project site, but would exit the Tunnel Hollow via the towpath heading downstream when loaded with removed rock material. There are many historic structures along the route from the rock stabilization area to the proposed spoil area. This route has been used before during similar options in the 1970s and 1990s with no known impacts to the historic structures. However, the potential exists for structures adjacent to the towpath, including stone retaining walls, to be affected by vibrations from passing trucks.