A Union Army inventory from Feb. 17, 1865, of the ordnance captured in Columbia lists, among other things: 
 
 — That confounded Union general whose name still draws hisses in South Carolina 150 years after he laid waste to the Capital City is causing yet another ruckus in Columbia. 
 
 On their way out of town, Union troops led by William T. Sherman dumped loads of captured Confederate ordnance – from cannonballs to ball cartridges, rammers, sabers, bayonet scabbards and knapsacks – into the Congaree River. 
 
 The artifacts have long been part of local lore, and the few pieces retrieved over the years indicated there might be more. 
 
 Now, through the science of sonar and metal detection, historians and researchers have better evidence of precisely where the munitions were dumped near the Gervais Street bridge in downtown Columbia. Excavators are planning how best to retrieve the artifacts. 
 
 “It’s really going to help us interpret what was a defining point for Columbia’s history, and, really, South Carolina’s history,” Joe Long, curator of the S.C. Confederate Relic Room and Military Museum, said of the impending finds. 
 
 The state of South Carolina will own whatever is pulled from the water. James Spirek, the state’s underwater archeologist, said the ordnance likely will be housed at the Relic Room, which is located in the same building as the State Museum, right at the Gervais Street bridge. 
 
 In 1865, Sherman’s troops kept what they wanted of confiscated rebel ordnance, then threw the rest into the river to keep it away from the Confederates. Better armed, Sherman then headed for North Carolina on his destructive march. 
 
 Getting the suspected weapons cache out of the water safely could be an issue. 
 
 No one’s certain what’s there or how dangerous it is. Explosives experts will be on hand to supervise. A high-end condominium complex, the State Museum and EdVenture children’s museum are nearby. 
 
 “Hopefully, none of it is going to blow up,” Long said of the weaponry, with a chuckle. 
 
 Complicating the process is the fact that the munitions lie beneath a 2-foot thick layer of tar that oozed from a long-closed gas-making plant located near what today is the Governor’s Mansion and lodged in that part of the river. 
 
 Consultants hired by the SCANA Corp. as part of the S.C.-based utility’s complex, $18.5 million clean up of the river found evidence of the artifacts. They would be removed along with the tar as the tar is hauled away over three years. SCANA announced in 2010 that the tar had been discovered and would be removed, but it did not say anything about the ordnance. 
 
 A draft of a September report to SCANA from Tidewater Atlantic Research and obtained by The State newspaper, states, “It has been confirmed that in 1865, during the Civil War, live munitions and other articles of war produced by the Confederacy were dumped into the Congaree River near the Gervais Street bridge by Union forces.” 
 
 Using sonar and magnetic metal detectors lowered from barges, researchers located 570 sites in the area of the river they tested and reported 218 as “exhibiting signature characteristics that could be associated with ordnance.” A total of 425 sites were reported as “potentially being ordnance.” 
 
 PART OF CITY’S LORE 
 
 Kayakers and river tour guides for years have talked about Union troops dumping ordnance. 
 
 “That’s what I told people when I was a river guide,” said Bill Stangler, now the Congaree’s Riverkeeper, who has been involved with permit negotiations for the dredging project. 
 
 Columbia was a manufacturing center for the Confederacy. It produced uniforms, weapons, powder and food for Robert E. Lee’s Army in Virginia. Several gunpowder plants lined the Columbia Canal and the river through what is now Guignard family property. 
 
 The city’s railroads and central location made it a hub for moving munitions, many made in Augusta, Long said. Columbia also was home to the Palmetto Armory, where some weaponry was made, he said. The armory is near what is now the Governor’s Mansion, on Arsenal Hill. The state arsenal, which doubled as a preparatory academy for Citadel students, housed Confederate munitions for shipping to rebel soldiers. 
 
 Accounts from J.F. Williams, author of a 1929 book on the burning of Columbia, show that for years after the war, Columbians would dive into the river to reclaim cannon balls and shells, according to the Tidewater report. 
 
 In the 1930s, political leaders in New Brookland – now known as West Columbia – organized a recovery project after two fishermen found ammunition. The organized dig through mud and silt turned up six 10-inch cannon balls, 1,010 rounds of rifle balls, 767 pointed rifle balls, some cast-iron cannon shells, time-fused bombs and an artillery ax, among other munitions, according to a 1930 article in The State newspaper. 
 
 “The 1930s recovery accounts for only a fraction of what may be present,” Tidewater consultants wrote. 
 
 Private salvage projects in the 1970s and ’80s turned up more material. 
 
 “Historic documentation clearly indicates that disposal of the ordnance was a significant event associated with the capture and burning of Columbia,” the consultants wrote. They said the tar cover, which stretches some 1,800 feet along the Columbia side of the river, includes artifacts that meet the criteria for a National Register of Historic Places site. 
 
 WHAT MIGHT BE THERE 
 
 A formal archeological study of the site has not been done, so precisely what will be uncovered during dredging remains a mystery. 
 
 But a Feb. 17, 1865, inventory of the ordnance and ordnance stores captured in Columbia lists 1.2 million ball cartridges, 100,000 percussion caps, 26,150 pounds of gun powder, 4,000 bayonet scabbards, 3,100 sabers, 1,100 knapsacks, 58 tents and 20 blacksmith vices, among much more equipment. 
 
 As Sherman’s army roared in from the west, three divisions and a Union cavalry unit camped Feb. 16, 1865, on the west bank of the Congaree directly across from the Capital City. 
 
 After a short battle at Congaree Creek near what is now Cayce, one of three corps of Sherman’s army spread out and began shelling Columbia, from among other places, the West Columbia shoreline. 
 
 Rebel troops burned the then-wooden Gervais Street bridge to slow Sherman’s advance, the Tidewater report states. 
 
 “Columbia citizens were trying to evacuate the city, and bales of cotton were dragged into the street to be carried off and burned to keep them from falling into enemy hands,” wrote the consultants, who studied the area’s history dating to the Paleoindian period between 10,000 to 12,500 years ago. 
 
 “Wade Hampton, hastily promoted to lieutenant general, was left to defend the city with General Joseph Wheeler’s cavalry,” the historical account continues. “Sensing the futility of the defense, Wheeler’s men began looting the city, ostensibly to prevent capture by the Union army. 
 
 “On the night of the 16th, Hampton announced that he planned to evacuate on the following morning, leaving behind the cotton which he was unable to transport. That evening, fueled by spirits dispensed without restriction, Union troops created more mischief through the city. When the cotton in the streets caught fire, they were unable or unwilling to contain the blazes. 
 
 “The result was the near complete destruction of Columbia,” the consultants’ report states. “Having the run of the countryside for several days, Union troops burned many homes and farms in the region.” 
 
 According to records from Union Gen. John E. Smith, it took 1,200 men and 50 wagons from 1 p.m. Feb. 18 to 6 p.m. the next day to destroy machinery, ordnance, ordnance stores and ammunition. 
 
 As the Capital City prepares to commemorate the anniversary of Sherman’s attack, current-day Columbians might soon see some of the weaponry that for decades has been shielded by black goo from a 20th century plant that produced “town gas” used for heating, cooking and lighting. 
 
 BELOW: An interactive map follows the path of Sherman’s troops through Columbia in February 1865. Mobile users, click here: ||||| — Imagine a temporary dam reaching deep into the Congaree River in the Vista, with walls that protrude some 14 feet above the water, as part of a three-year environmental cleanup that also is likely to uncover Civil War munitions. 
 
 SCANA Corp.’s $18.5 million project to remove about 40,000 tons of black tar discharges from a power plant that closed six decades ago should look something close to that. 
 
 Tar was discovered in the water near the Gervais Street bridge several years ago. SCANA in 2010 told the public it would have to come out. But only now is anyone beyond a select few finding out the scope of the project and the fact that studies have shown that buried beneath the tar are objects that are likely captured Confederate ordnance dumped by Union troops 150 years ago. 
 
 The stone cofferdam under consideration by state and federal environmental regulators calls for it be 171/2-feet tall, to have a 60-foot base and to snake as much as 3,990 feet around the edges of the dam, between the Gervais and Blossom street bridges. Behind the dam, about 15 acres of river bottom will be exposed in stages and scraped clean to the bedrock. 
 
 The project will be surrounded by 2,100 feet of fencing, 210 warning signs, security guards and include construction of a debris-processing shed, a paved truck-hauling road and a prefabricated bridge to protect a city sewer line. 
 
 From May to December each year, river water would be diverted to the West Columbia side while workers remove tar described as being solid to taffy-like and averaging 2-feet thick. 
 
 The cap over natural sediment is up to 150 feet wide and 1,800 feet in length. The target area extends plume-like from the Columbia side of the riverbank to nearly 200 feet into the scenic river that measures about 800 feet wide at that point. The tar emits a distinctive oil-like odor and health officials say it poses a risk to humans only by direct contact. 
 
 Those descriptions are taken from the utility company’s formal proposal to regulators who have yet to approve required permits because they have many questions about the project, first proposed in 2002. 
 
 SCANA’s director of environmental services, Tom Effinger, would not discuss details of the project, citing the ongoing permitting process. Neither he nor a SCANA spokeswoman would acknowledge the likelihood of military ordnance under the tar cap. 
 
 “We don’t have any direct knowledge of ordnance,” Effinger said. “We don’t know if it’s hubcaps or what is there.” 
 
 Yet Effinger did not dispute data from a survey it commissioned from a Columbia research company. A September 2014 draft report by Tidewater Atlantic Research obtained by The State newspaper, states that a list of “potential unexploded ordnance” locations were found. More than 400 samples were found as “potentially being ordnance.” That includes 67 that demonstrate “signature characteristics” of what could be ordnance. 
 
 Congaree Riverkeeper Bill Stangler said he’s been working with the utility on the project for about 21/2 years as an advocate for the river. “I don’t know how much we’re supposed to say about that,” Stangler said. 
 
 Effinger said SCANA’s message is one of reassurance. 
 
 “Whatever we do in the river, we’re going to do it right and we’re going to do it safe,” the utility executive said. “We’re going to make sure we do this thing the best way possible.” 
 
 Project being changed, shrunken 
 
 SCANA, its subsidiary, South Carolina Electric & Gas Co., and the regulators decided Wednesday that the utility will submit a revised proposal that would scale back the size of the coffer dam and possibly to use material other than stone, Jim Beasley, a spokesman for the state’s environmental regulatory agency, said last week. 
 
 The size could be reduced “perhaps greatly,” the Department of Health and Environmental Control spokesman said. 
 
 Beasley would not specify the proposed changes, other than to say, “The design is going through substantial revision. The overall effect of the revised design will be to reduce in scale the size of the coffer dam, and, possibly, to use different materials.” 
 
 DHEC and the U.S. Army Corps. of Engineers, the lead federal agency on the project, have raised a number of questions about it. 
 
 Brice McKoy, supervisor of the Corps’ Columbia office, said its list of concerns range from water topping the temporary dam when the river is flush to backwater effects and clean up procedures. 
 
 He declined to itemize the issues his agency has but said they amount to about 21/2 pages. That’s not an unusually large number of concerns for a cleanup of this magnitude, McKoy said. 
 
 “This is a very complex project,” he said. “Imagine damming up half the Congaree River. We want to make sure that this thing is done absolutely correctly. We’re talking public safety, so we don’t want to rush (SCANA). 
 
 “The corps does have concerns about the project and those concerns are currently being addressed by the applicant,” McKoy said. 
 
 SCANA officials would not discuss the talks, which have gone on throughout the permitting process. Public discussions will occur once permits are finalized, they said. 
 
 Effinger declined to detail the issues raised by regulators. But he said the dam’s height is one of the key matters in question. 
 
 None of the parties to the dredging project would say when permits might be approved. 
 
 The budget of $18.5 million – all paid by the utility – will not result in rate increases for SCE&G customers, Effinger said. SCANA has a fund set aside for environmental cleanups, among them the Congaree River project, which is one of the largest, he said. 
 
 Some 22,000 truckloads of debris will have to be removed from the site, according to a source long familiar with the project. 
 
 The truck access route to the project is to be moved from SCANA’s first proposal in the Vista southward, near the University of South Carolina baseball stadium, said Dixon Lee, an attorney who lives in City Club on Gervais Street, the closest residential site to the dig. Owners in the high-end complex of 38 condos overlooking the river opposed the original route, which would have taken trucks along Gervais, Huger, I-126 and I-20 to a Richland County landfill. 
 
 Lee said he and other City Club owners have held numerous meetings with SCANA officials for 18 months. 
 
 “Our chief concern was that it would create a traffic nightmare,” Lee said. “You can imagine six months for three years of huge trucks going in and out. We got a huge accommodation when they agreed to go the other way.” 
 
 Effinger would not talk about the new route. He said the state Department of Transportation and the city of Columbia must first finalize it. 
 
 Rebel munitions 
 
 On Feb. 17, 1865, Gen. William T. Sherman’s Union army stormed and burned Columbia after shelling it from afar as they headed north after taking Savannah. 
 
 An inventory of the rebel ordnance and ordnance stores captured that day lists: 
 
 • 1.2 million ball cartridges 
 
 • 100,000 percussion caps 
 
 • 6,000 unfinished arms 
 
 • 4,000 bayonet scabbards 
 
 • 3,100 sabers 
 
 Some of those weapons have long been believed to be at the bottom of the river. Through the years, fishermen and swimmers have found some munitions. And in the 1930s, a large cache was salvaged from the sandy bottom. 
 
 But how much history is buried under the tar and its condition remain mysteries. 
 
 James Spirek, the state’s underwater archeologist, said he’s not persuaded that lots of Civil War armaments will be found. “I’m sure there will be some interesting items. I don’t anticipate huge volumes.” 
 
 But historians and Civil War enthusiasts are excited about what treasures the dredging will unearth. 
 
 The pollution 
 
 Instructor Bill Thomas discovered the tar during a lesson in May 2010 while teaching inexperienced kayakers how to do “Eskimo rolls” so they could right themselves after tipping over. 
 
 “I waded into the water,” Thomas said. “First I noticed the smell. When I got out of the water there was a gooey, black gunk ... all over my feet. It smelled strongly of petroleum.” 
 
 He reported what he saw to DHEC, which began looking into the complaint. 
 
 Downstream water quality effects from the tar are negligible, according to documents reviewed by the newspaper in regulatory files. The Congaree is one of the city’s sources of drinking water as well as being popular for fishing, walking and recreation. 
 
 The coal tar came from a gas-making plant once located on Huger Street between Hampton and Williams streets. It was completed in 1906 and closed in 1954 before there were national pollution standards. 
 
 The plant produced flammable “town gas,” which was used for heating, cooking and lighting before the city had natural gas pipelines. A series of purchases of the company that owned the plant ended when SCE&G was listed as its owner by 1950, according to documents filed as part of the environmental permitting process. 
 
 Records SCANA has sent to regulators show more than a dozen different chemicals were found in river sediments at levels of concern. 
 
 Those include benzene, which can cause cancer, and related compounds. In some cases, the levels were higher than levels typically considered safe in soil. 
 
 Benzene was discovered in an alluvial fan and sand bar of the Congaree, as well as some other areas. They are at concentrations that exceed residential screening values, according to the Interstate Technology Regulatory Council. 
 
 Concentrations of pollutants above screening values often require further investigation. But there are no national criteria or standards for chemical concentrations in sediment – only guidelines, SCANA’s project manager of the cleanup, Bob Apple, wrote in a Jan. 15, 2013, report to DHEC. 
 
 A risk assessment of the project site found “the cumulative ... cancer risk was exceeded for the recreational user. Therefore, it may be concluded that the cumulative ... cancer risk would be exceeded for the Congaree River sediment containing (the tar),” Apple’s report to DHEC states. 
 
 Environmental challenges 
 
 Apple’s report also noted the project area contains a diverse ecology, including flora. 
 
 The short-nosed sturgeon is on the federal and state endangered species list while the Rafinesque big-eared bat is listed as endangered only by federal officials. The Gervais Street bridge is a roosting area for the bats. Several species of mussels and the Rocky Shoals spider lily also inhabit the area. That lily is a “species of concern” under federal standards. 
 
 Apple cited a 2007 short-nose sturgeon study done as part of relicensing a hydroelectric plant found no captures of the fish or its eggs. 
 
 Attorney and City Club resident Lee said he did Internet searches that showed that a short-nosed sturgeon has not been sighted in rivers immediately around Columbia since the 1920s. 
 
 Lee has dubbed the fish “the hypothetical short-nosed sturgeon.” 
 
 Yet the prospect of the fish being in area rivers has forced SCANA to drop plans to do year-round work on the project, Lee said, citing that he and his neighbors received their most recent update from Apple in December. 
 
 And the utility company has offered to shorten work on the project by a year, the attorney said. SCANA is proposing two stages of dredging instead of three to ease any impact on the sturgeon, Lee said. 
 
 Effinger would not discuss proposals that have not been formalized in a permit. 
 
 Apple told Stangler, the riverkeeper, in a July 31, 2014, letter that the shore, including the site of a processing facility for the debris before it is trucked away, will be disturbed minimally and will be repaired after the project ends. 
 
 City Club homeowner’s association president, Rebecca McMillan, said she supports the cleanup despite the inconveniences. 
 
 “Our (City Club) community – which this is not something that we coveted – feels we’ll be much better off for not having that tar in the river.” 
 
 Fellow resident Mary Langston sees a broader advantage. “In the long run, it’s going to be a benefit for all of Columbia.” 
 
 Staff writers Sammy Fretwell and Matt Walsh contributed. Reach LeBlanc at (803) 771-8664.
– In 1954, a gas-producing plant closed near the Congaree River in Columbia, SC. But its presence lingers, in the form of roughly 40,000 tons of "taffy-like" black tar that need to be removed from the river. The State reports on a most unusual side effect of damming the river to do so: the possible recovery of Confederate munitions seized and then dumped by Gen. William T. Sherman's Union army a century and a half ago. The State includes a list of what Union troops logged as having captured from their Confederate counterparts in taking the city on Feb. 17, 1865: 1.2 million ball cartridges, 100,000 percussion caps, 4,000 bayonet scabbards, 3,100 sabers, 1,100 knapsacks, and more. Whatever they didn't bring with them as they marched toward North Carolina they dumped in the Congaree to keep it out of Confederate hands. The energy company SCANA Corp. will facilitate the Congaree cleanup, which involves exposing about 15 acres of riverbed and removing a tar cap that's, on average, 2 feet thick—along with any Civil War artifacts, which a separate State article notes would belong to the state. While the company's director of environmental services says "we don't have any direct knowledge of ordnance," the State points out he also didn't deny the findings of a September draft report SCANA commissioned that involved the use of sonar and metal detectors. That report identified 218 sites as "exhibiting signature characteristics that could be associated with ordnance." Though items have been documented as being salvaged in the 1930s, 1970s, and 1980s, the state's underwater archaeologist isn't expecting a mass cache to surface this time around. "I'm sure there will be some interesting items. I don't anticipate huge volumes," he says. (An "underwater Pompeii" was recently discovered off Greece.)