SEWER-LINE CORROSION CONCERNS ENGINEERS AND TOWN OFFICIALS

                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: SATURDAY, January 16, 1993                   TAG: 9301160121
SECTION: CURRENT                    PAGE: NRV-2   EDITION: NEW RIVER VALLEY 
SOURCE: PAUL DELLINGER STAFF WRITER
DATELINE: PULASKI                                LENGTH: Medium
SEWER-LINE CORROSION CONCERNS ENGINEERS AND TOWN OFFICIALS
Pulaski town officials met with engineers Friday on a pilot study aimed at reducing corrosion in a sanitary sewer line to Peppers Ferry.
The corrosion is caused by hydrogen sulfide in the line. The problem was discovered in the fall of 1990, but has not been easy to solve.
"We've been fooling with this for about two years now," said Town Councilman Andrew Graham during Friday morning's meeting of council's Utilities Committee.
The committee met for about an hour in closed session on legal matters related to the problem. No action was taken when the committee returned to open session.
Engineers from Draper Aden Associates said the introduction into the line of bioxide, an oxidizing agent, looks like the answer.
It should control the amount of hydrogen sulfide, which combines with water in the line and produces sulfuric acid, causing the corrosion.
Hydrogen sulfide occurs in most sewer lines. It builds up more in this one because of the time it takes for the sewage to move through the line from Pulaski to Dublin, and because the line is not vented.
Fred Pribble of Draper Aden said the firm coordinated with regulatory agencies about four months ago to make sure there was no problem in using the bioxide.
"We're not going to be the first utilizing bioxide in this area now," he said. Roanoke is using it to curb odor problems associated with hydrogen sulfide, he said.
Pribble said the study on its use could have been started last month, but winter was a bad time for testing because of water flow is usually higher in winter, minimizing the sulfide problem. The study probably will start in April, he said.
He estimated it would take 30 to 60 days to get the system balanced.
Once the sulfide is controlled to a reasonable level, the line can be inspected and the problems pinpointed and fixed. It also can be vented, something Pribble said the town would not want to do while sulfide levels were still high because of the odors it would produce.
Facilities to add bioxide to the system probably will be installed at both its pump stations, he said. Mayor Gary Hancock asked if the system could continue working uninterrupted if the bioxide treatment proves effective.
The town will have that option but not much time to make the decision of whether to interrupt service or not, Pribble said. "I'd say by late May you should know."

by Bhavesh Jinadra by CNB