Campbell's_Covered_Bridge_ECR_for_bidding.pdf

Campbell’s Covered Bridge

Existing Condition Report

Fall 2019

This report was prepared for:

Greenville County Department of Parks, Recreation and Tourism

Report prepared by:

Preservation South, LLC PO Box 1595

Greenville, SC 29621 preservationsouth@bellsouth.net

770-894-2981 mailto:preservationsouth@bellsouth.net

Report Background

Preservation South was engaged by the Greenville County Department of Parks Recreation and Tourism to undertake an assessment of the current condition of Campbell’s Covered Bridge. The assessment is meant to provide background and guidance for the county to fulfill their stewardship responsibilities for this important historic resource. This assessment was to be conducted to determine the condition of the bridge’s historic fabric and gain a better understanding of the bridge’s original construction and its alterations and renovations over time. The report was to provide recommendations on the correct treatment of historic materials in order to avoid incompatible repairs and future maintenance issues.

Survey Methodology

This Existing Conditions Report was created based upon historic research of the bridge’s use and alteration over time in order to prove a baseline for the assessment of the bridge. This information then guided onsite analysis of the bridge and its various elements. The background information and on-site evaluation allowed the identification of character-defining features that were authentic, and those that were not. The bridge’s historic elements were then methodically assessed for condition issues such as water damage, termite activity, inappropriate construction techniques, etc. and recommendations for treatment were provided based upon the Secretary of the Interior’s Standards for Rehabilitation. The standards for rehabilitation are the most commonly used of the four secretary’s standards and allows for flexibility in materials used in the repairs while maintaining the historic visual character of the building. Please refer to page 44 for a full list of the rehabilitation standards. The information gathered was then organized by category into the following report.

Survey Scope and Limitations

This report is focused on the Historic Campbell’s covered bridge and its immediate surroundings that directly affect the bridge and its components. The report provides a brief general description of the condition issues identified herein and provides recommendations based on the Secretary of the Interior’s Standards for Rehabilitation. This report does not utilize any invasive assessment techniques.

The consultant did not survey the building for asbestos, lead paint, mold, or other hazardous materials.

The findings are based on a preliminary investigation and should not be considered as binding. The as built plans included in this study were prepared from on-site measurements and observations but are not construction documents.

Site Background:

Campbell’s Covered Bridge is located in north east Greenville County just off Pleasant Hill Road. The bridge crosses Beaverdam Creek and is the only surviving covered bridge in South Carolina, a state that once had twenty covered bridges. The widely publicized date of construction is 1909, though oral history from Mr. Furman Sudduth states the building was constructed in 19111. Even at only 38 feet in length the bridge replaced a smaller wooden “banistered” bridge. This bridge was washed out in August of 1908 during a massive flood in the upstate where 20 inches of rain fell in just 22 hours.2 According to Mr. Suddeth his father operated a large sawmill close by and supplied the lumber for the bridge. The contractor, Mr. C. I. Willis won the contract with the low bid and apparently lost money on the project resulting in him taking two years to payoff the lumber order. Suddeth also accounts the bridge originally had a cedar shingle roof made of shingles brought from California3.

The bridge is named for Alexander Lafayette Campbell who operated a grist mill just down stream from the bridge. The mill utilized a stone dam upstream from the bridge to create a mill pond to provide water to run the mill. According to Suddeth’s accounts the water was carried from the dam through a wood sluice to the bridge abutment where it then traveled through the abutment in a homemade pipe created by metal barrels, once on the other side the water again traveled through a wood sluice to the mill’s water wheel. The Grist mill stood at least until the 1980’s, but the site of the mill is still evident below the bridge. (See page S1 in the appendix)

The bridge provided a more direct route for travelers in the area until Pleasant Hill Road was rerouted 500 feet south in 1951. In 1964 the Crescent Garden Club undertook the first “restoration” of the bridge. Details of this project are vague but oral history from John P. Ashmore, a former Greenville County Supervisor states that more than fifty percent of the bridge was replaced.4 The replacement of that amount of original material is significant and would be considered heavy handed by today’s standards. It was during this work that the building was likely first painted to make the new elements blend in with the originals.

By 1979 Campbell’s covered bridge was the sole surviving covered bridge in the state. That same year the bridge was featured in a low budget horror movie called “The Day of Judgement5.” In 1982 Greenville County dumped mounds of dirt in front of both entrances to the bridge in order to stop vehicular traffic across it at the recommendation of the state’s Department of Highways and Public Transportation. That same year county council considered various options to restore the bridge, options ranged from reopening it to vehicular traffic, to disassembling it and relocating it to a park near Piedmont.6 Public outcry against the relocation of the bridge resulted in County Council turning down the recommendation to relocate it that August. At that time associate county planner Stephen Tanner was to undertake a feasibility study for using the site as a park as part of his Master’s Thesis but no

1 The Last Covered Bridge, Echoes Volume 4, 1983 2 Henderson, Gary, Campbell’s Covered Bridge a Landmark, Spartanburg Herald Journal. December 12, 1993 3 The Last Covered Bridge, Echoes Volume 4, 1983 4 Belli, Steve Covered Bridge: a monument to the past, The Greenville News, June 30, 1993 5 Staff, Film to Include Greenville County Bridge, Greenville News, 1B May 5, 1981 6 Campbell, Dean Greenville County holds fate of last covered bridge, Discover Upcountry Carolina, Vol. 2 No.1, October 1982 record of that document has been located.7 In 1990 Cunningham Walters Construction in Greer completed another “restoration” of the bridge for Greenville County. During that restoration the bridge was lifted off its foundation and the wood sills replaced with pressure treated timbers. The 1964 tin roof was replaced at this time with galvanized steel which was meant to last longer than the tin8 No records of this work were located but it is possible to see elements of that bridge that were replaced during this work because they utilized modern finished lumber which is noticeably smoother than the rough cut lumber used in the original construction and in the 1964 work.

Image 1: Historic image of the bridge circa 1982

7 Burritt, Chris Neglect of Covered Bridge upsets nearby residents, The Greenville News, March 9, 1983, Pg. 3C 8 Belli, Steve Covered Bridge: a monument to the past, The Greenville News, June 30, 1993

Site:

Campbell’s Covered Bridge is built in a low stream bottom with steep hillsides on either side. The bridge is set across Beaverdam Creek in a section of shoals where the creek elevation drops a significant amount. These elevation changes cause the site to suffer from constant erosion of both the bridge abutments and the creek bank.

The drop in the stream’s elevation increases the speed of the water which was ideal for the grist mill that used to share the site but also scours the base of the bridge abutments.

On the north side of the bridge water coming down the hillside is collected primarily in a retention pond which then discharges on the upstream side of the bridge. The retention pond does not collect all the runoff and a significant amount runs onto the roadbed and eventually onto the bridge itself or off the sides. This run off has created substantial erosion of the edge of the roadbed especially on the downstream side of the northern approach. The water that reaches the bridge is trapped by a subtle hump in the roadbed that appears to be left over from large berms created by Greenville County to close the bridge to vehicular traffic in the 1980’s. This water has led to rot and deterioration of some the elements of the bridge’s Howe Truss system, especially on the northwest corner.

This side of the site also has at least two separate natural springs on the hill side downstream of the bridge. These springs keep the hill saturated which is problematic where the saturation undermines the bridge abutments. The large spring inside the faux well is drained through a section of corrugated drainpipe under the path and out onto the hill. This pipe is clogged and likely collapsed which is causing the water to back up and spill out onto the path and creating a mud pit out of the pedestrian walkway.

On the south side of the creek the former roadway meets the bridge at a much steeper slope. This brings more water in contact with the bridge and the significant cross slope of the roadway forces quite a bit of water off the road where it runs down the upstream side of the bridge. This run off has caused a large trench to be eroded along the upstream side of the south abutment. This erosion risks undermining the abutment over time.

The existing split rail fence is not in particularly good shape and is not historically accurate for the site.

Historic images of the site show a wooden guard rail running along the abutments made of large square wood posts set in the ground and rough-cut rails fastened to their face. This guardrail will not meet building code requirements, but the existing split rail fence does not meet code either.

Recommendations:

• The stormwater runoff on site needs to be addressed first to stop further damage to the bridge and any repairs made. The north approach to the bridge should be regraded to slope away from the bridge all the way to the hillside (Refer to page A2 of the appendix). On the south side of the bridge a low berm in the gravel should be installed across the roadway to direct run off northwest into the woods Refer to page A1 of the appendix).

• The two spring heads on site should be re-piped down to the creek bank to stop the saturation of the hillside. For the upper spring located inside the faux well the existing corrugated drainpipe should be removed and a new 6” French drain line should be installed and buried all the way down to two feet from the creek bank. The other spring near the abutment should also have a catch basin installed and a 6” French drain line installed and buried in the same manner as outlined above (Refer to page A2 of the appendix).

• The creek access trail to the southwest of the bridge should be rerouted away from the bridge.

A new trail has been forged through the laurel in a more direct route down to the shoals and site of the former dam. The stone steps from the old path should be relocated to the new path and additional large stepping stones added. The former pathway should be scarified and replanted with mountain laurel to prevent further erosion (Refer to page A1 of the appendix).

• The large trough eroded on the upstream side of the bridge should have the organic matter removed and then should be backfilled and compacted (Refer to page A1 of the appendix).

• The split rail fence should be removed, and the wood guardrail system should be recreated. The guardrail should be painted to match the bridge with the exception of the face of the end posts facing the flow of traffic, this should be painted white so it would have acted as a reflector for nighttime travelers originally (Refer to pages A1 and A2 of the appendix).

Image 2: existing split rail fence shifting due to erosion

Image 3: Upper spring head drain pipe clogged up

Image 4: Existing trail showing erosion near abutment

Image 5: Cut through trail further west to be reworked as main trail

Abutments:

The bridge rests on masonry abutments constructed on either side of the creek. The abutments are comprised of stacked local stone from the creek bed up to a height of approximately eight feet which run the width of the bridge and then extend back up the sides of the road approach. The rocks appear to have been dry stacked originally and there are statements in the early articles on the bridge that there are bedrock outcroppings behind them though there is no physical evidence to support that claim.

The rocks have been mortared together in the past using Portland cement which was applied in a poorly tooled fashion. Above the stacked stone an approximately four-foot-tall section of board formed concrete was added likely during a previous restoration effort. It is impossible to know without invasive exploration, but it appears that this concrete has no internal reinforcing. This hypothesis is supported by vertical cracks which have formed at the point where the retaining wall on the side of the roadway intersect the abutment. The cracks appear to be the result of erosion in the roadbed pushing the concrete portion of the retaining wall out on the unsecured end. Additional stone loss from the stacked stone portion of the wall on the downstream side of the bridge’s north abutment is possibly caused by visitors removing stones but is likely due to erosion.

Recommendations:

• The deterioration of the abutments should be repaired as a top priority. Two soil nails should be installed in each of the cracked poured concrete retaining walls to hold them in place. The goal of the nails is to stop the wall from moving further, the nails are not meant to pull the wall back into place (Refer to page A1 and A2 of the appendix).

• Two helical ties should be installed laterally across each crack in the poured concrete walls.

Grooves should be cut halfway into the wall slightly longer than the helical tie. The tie should be installed in the groove and then the groove grouted out flush with the surface of the wall (Refer to pages A1 and A2 of the appendix).

• The large missing stone on the downstream face of the north abutment should be reset in the wall using a type N mortar that matches the existing pointing mortar in color and texture (Refer to page A2 of the appendix).

• The stacked stone portion of the abutment should be pointed in a type N mortar where the pointing mortar is missing or cracked. This mortar should match the existing intact mortar in color and texture (Refer to pages A1 and A2 of the appendix).

• The stacked stone wall on the downstream side of the north abutment should be extended further north to the point where the abutment ends into the hillside (Refer to page A2 of the appendix).

Image 6: Northeast abutment showing erosion and deterioration

Image 7: Southeast abutment showing crack in concrete work

Image 8: Northwest abutment showing mortar loss

Image 9: Erosion along southwest abutment wall

Image 10: Significant erosion above the existing northeast abutment wall

Image 11: Stacked stone with no mortar to retain the wall.

Howe Truss System:

Covered Bridges were made using various support methods depending on their span and period of construction. The Campbell’s covered bridge utilizes the Howe Truss which was popularized in the late nineteenth century for supporting large loads over great distances. The truss combines diagonal members that are in compression as well as vertical members that are in tension. This combination of tension and compression made it ideal for carrying large loads, therefore the Howe Truss is often seen in railroad bridges and was used frequently in the first half of the twentieth century in metal truss road bridges.

The Howe Truss at Campbell’s Covered Bridge utilizes rough sawn dimensional lumber paired with iron rods (for tension (Refer to page A6 of the appendix for a schematic of the Campbell’s Howe Truss) The bottom and top plates of the trusses are comprised of 2x12 built up to form a beam. Deterioration was noted in one of the boards used in the bottom beam in the northeast portion of the bridge. This deterioration is likely due to water causing rot and attempts have been made to strengthen it by the addition of horizontally oriented boards above and below this portion of the beam. The two trusses run down either side of the bridge, they are then connected by horizontal beams which support the road deck. The threaded rods come through these beams and have threaded ends which connect rectangular metal plates and large square nuts holding the roadway up. One of the tie rods on the upstream side of the bridge is missing a nut. Additional diagonal bracing runs between these beams as well as connecting the top of the trusses to inhibit lateral movement. There are signs that some of these horizontal members have been bored into by carpenter bees. The carpenter bees create channels in the boards in order to lay their eggs, over time these channels can weaken the board.

Recommendations:

• The two horizontal boards added on the upstream Howe truss should be removed. The deteriorated board in the middle of the bottom beam should be repaired using Abatron “woodepox” per the manufacturer’s instructions provided the deterioration is not deeper than two inches in any one area. If the deterioration is more significant a new pressure treated member that matches the rest of the surrounding members in dimension and profile should be installed(Refer to page A3 of the appendix).

• A new iron nut should be made to match the existing nuts on the end of the tie rods, it should then be installed on the tie rod which is missing the nut. It should be tightened only to finger tight.

Image 12: Howe Truss system

Image 13: Deterioration of bottom truss underneath the horizontal board that has been added.

Image 14: Missing nut on the bottom of one of the tie rod

Sheathing:

The internal framing system is sheathed in vertical rough sawn lumber which was installed in a board and batten pattern. This means that the wide boards are installed vertically on nailing strips outside the truss system. There are gaps between the boards to allow for expansion of the siding, these gaps are then covered with smaller wooden strips called battens which create a solid wall. There are signs that the sheathing has been repaired in the past with the introduction of smoother boards. Currently there are two areas of battens that have come loose and need to be either reapplied or replaced. The sides of the bridge have three angled braces projecting from each side of the bridge. These braces were meant to keep the bridge from twisting as vehicles moved across it. Over time these braces have experienced significant deterioration and the sheathing is in need of replacement.

Recommendations:

• The existing sheathing is in good shape and should be retained. The loose battens should be reattached. Where sheathing boards or battens need to be replaced, they should be replaced with rough sawn wood that matches the original in dimension and profile. All new boards should be primed on all six sides prior to installation. Wire nails should be used for installation (Refer to pages A4 andA5 of the appendix).

• The existing angle braces on the sides of the bridge are significantly deteriorated. The sheathing should be removed and replaced as described above. If the timbers making up the brace are deteriorated as well they should be repaired using scarf joints to attach new material in place of the deteriorated portions (Refer to page A3 of the appendix).