Water Beyond 2000 - Upground Reservoir Project
"The Columbus Upground Reservoir is the largest single geomembrane lined basin ever constructed on earth." - Daniel S. Rohe
The Columbus Upground Reservoir is the culmination of more than 10 years of work by the City of Columbus, Ohio - Department of Public Utilities. An upground reservoir is a man-made water basin separate, or off-stream, from its water source. When stream flows are adequate, water will be pumped from the Scioto River and diverted to the Columbus Upground Reservoir, to be stored for future use. When needed, water will be released back into the river to flow by gravity to the Columbus water treatment plant.
The first of three CUGR reservoirs is the 843 acre R-2 basin. When completely filled it can contain more than 9 billion gallons of water! The water will be pumped from the Scioto River by 4 vertical turbine pumps, each capable of pumping 40 million gallons of water per day through the 20,000 foot long, 72 inch diameter pipeline from the river pump station to the reservoir. The reservoir is being lined with 37 million square feet of 40 mil polypropylene geomembrane liner fabricated and installed by Environmental Protection, Inc. It is the world's largest geomembrane liner project ever constructed in a single operation. The $122 million dollar project is scheduled to be completed in October 2013.
EPI began fabrication of the 40 mil geomembrane panels in 2011. Fabrication continued throughout the winter of 2011-2012 in order to stockpile enough fabricated geomembrane liner panels ahead of the planned rapid installation schedule. Rolls of polypropylene from the geomembrane manufacturer are unwound, the edges overlapped, and are then thermally welded together to ultimately form 125 foot by 250 foot fabricated geomembrane panels. Each panel is 31,250 square feet and weighs approximately 6,250 lbs. Thermal welded factory seam samples representative of each panel are tested for every shift and a duplicate sample from each test is archived by the project QC Team. All completed factory fabricated seams are air lance tested according to ASTM D4545. The panels are then rolled on hollow cores and stored at EPI's facility or shipped directly to the site. Approximately 37 acres of liner were installed in the fall of 2011.
In the summer of 2012, liner panels are now being placed at an average rate of 12 panels per day. That is an average is 375,000 square feet per day in place, tested and covered with a 10 ounce geotextile. This requires a herculean effort by Beaver Excavating to prepare more than 8 acres of subgrade each day for liner installation. However, the very dry weather this spring and summer have been ideal for earthwork construction.
As the liner is installed, welding commences immediately, followed by air channel testing of the field seams, GPS surveying to locate the four corners of each panel, removing field seam samples for independent laboratory destructive testing, a GPS survey of the location of the removed sample, and covering the liner with nonwoven geotextile with heat welded overlap seams. EPI foreman Jerry Pryor coordinates four EPI crews who each day deploy the fabricated geomembrane, thermal weld the liner seams, air channel test seams and make any repairs, and finally, deploy and weld the geotextile. Beaver Excavating then immediately begins the process of covering the liner with eighteen inches of soil.
The EPI job site chart at the left indicates that liner installation is at 34% complete as of June 26, 2012.UPDATE: On July 20, 2012 Liner Boss Brad DeArment reported that 379 acres are in place since the fall of 2011 and the liner is now 43.5% complete.
From April 2012 to July 20, 2012, 342 acres of 40 mil polypropylene liner have been installed. With more than 3 months of good weather left, by the end of 2012 EPI will have fabricated and installed the largest amount of liner ever installed by one company on one project in a single construction season. All of this requires a monumental quality control effort by EPI and the project team.
For an idea of the scope of this geomembrane liner project, 342 acres so far in 2012:
Equals 14,897,520 square feet (1.379 million M2);
Equals >one half of a square mile (a square mile is 640 acres);
Equals 475 panels;
Equals 204,000 feet of field seam welded (that's 38+ miles);
Equals more than 425 hours of thermal welding;
Equals 38 miles of dual track air channel testing;
Equals 203 destructive seam samples removed and tested by an independent laboratory.
Initial destructive test results for the first several weeks of field installation this spring were very positive and reassuring. QC inspectors discussed the possibility of decreasing the destructive seam sample removal rate from 1 per 1,000 feet to 1 per 2,000 feet. A 50% reduction.
But EPI Project Manager Brad DeArment said, "No!" His reason, "We don't have any problems now with welding, and by continuing to test this often we'll insure we won't have any problems in the future".
Testing continues to be done at one per 1,000 feet of field seam. The result: 99.5% pass. Only one failure in 203 independent lab tests (and only 2 specimens out of 10 in that sample failed). A remarkable QC record from Environmental Protection, Inc.
After soil covering is complete, the lined area is surveyed by Geo-Logic Associates with an extremely sophisticated geoelectric leak location survey that can locate holes in the liner as small as a pencil. Coupled with a precise GPS survey system accurate to within inches, the system will map the entire bottom of the basin in order to find and eliminate any holes in the liner. This survey is done according to ASTM D7007. A DC voltage is applied to the soil covering the liner and the power source is grounded to the soil outside the geomembrane. With the liner acting as an insulator between the two, the survey system is capable of locating a hole in the membrane as small as 1/8 inch.
In June 2012, a Geo-Logic Associates team led by Abigail Beck completed a survey of 150 acres of liner (area 2 on the photo above) installed and welded by EPI. QC engineers had discussed the potential for leaks that might be found in this project, and theorized that 1.5 holes per acre could be a number they might anticipate when the survey was actually done. That rate would result in a potential of 225 holes for this large area.
But in fact, they located only 15 measurable holes shown in red on the survey photo [below]. Forensic analysis of the holes revealed 9 were caused by a stones forced through the liner from above, 4 by equipment damage, and 2 by cuts during installation. All damaged areas were excavated, repaired, covered and re-surveyed to be sure no other holes were missed.
EPI continues to provide Quality Control above and beyond expectations at this signature site. For more information about the Columbus Upground Reservoir, click here.
Updated Google Earth photo of the Project Today!
For more information call 800-OK-LINER today!