Hiding a 96 Inch Pipeline in Your Neighbor's Backyard

When DeKalb County Department of Watershed Management decided to replace a 50-year old raw water transmission main with a new pipeline, the obvious choice for routing of the main was in the same alignment as the existing pipeline. In this case, the existing cross-country alignment had advantages of simpler design, reduced construction cost and almost no traffic disruption. Many lessons learned later, the advantages of the cross-country alignment were tempered by much greater coordination with hundreds of stakeholders. This experience should offer caution for engineers who may jump at the obvious choice of cross-country easements. Three raw water transmission mains provide the entire water supply for over 750,000 residents in DeKalb County, serving a large portion of the Atlanta, Georgia area. The pipelines traverse a 13,000 foot easement from a raw water pumping station on the Chattahoochee River to the Scott Candler Water Treatment Plant (WTP). The existing pipelines were installed in 1942, 1960 and 1980. A new pipeline was required to alleviate the issues of pipe transient damage, reliability and capacity. The 1960 pipeline was the weakest of the three mains and subject to many ruptures over the years. It was decided to replace the old 48-inch main with a new 96-inch welded steel pipeline, which not only would be more secure but would increase the reliable capacity from 140 mgd to as much as 360 mgd. This will provide all future capacity to the County's water customers for the next 50 years. However, in the past 50 years, the character of the alignment has changed dramatically. What was once a rolling easement in open fields is now home to one of Georgia Power Company's major transmission lines, two large oil pipelines, a sewage treatment effluent pipeline, an apartment complex built over the old mains, and up to 80 individual homeowners who have fenced in backyards over the easement. The project required over four years of easement acquisition, coordination with major utilities, extensive agreements with Georgia Power Company, and two years of permitting from three counties and two new cities. Finally, in 2011, the pipeline was completed with limited construction delays and less than 2 percent change orders. This paper discusses issues that were addressed and lessons learned in construction along complex easements with active stakeholder involvement.