special process techniques with project specified geosynthetics for sludge lagoon covers
The construction of a capping system on top of a sludge lagoon is a technically hard to please task. The weak sediments and their low shear strength afford higly sophisticated and plant optimized solu-tions. In the past the use of plant specified fabricated geosynthetics and a detailed planned construction work results in cost and time effective solutions. Based on two topical projects the main characteristics for choosing the reinforcement, the design and the work schedule will be presented.
This paper provides recommendations for design and construction of sludge lagoon covers. Boundary conditions are declared for the influence of the choice of material and installation pattern. Anchor-age of the reinforcement can be performed in- and/or outside the lagoon according to the place available and the danger of squeezing out of the sludge. Dif-ferent raw materials allow the use of geotextiles in nearly every chemical environment. Geocompounds or wovens have a reinforcing and seperating func-tion and are predestinated for sewing larger panels. Geogrids in combination with non-wovens or wov-ens can be used for all size of lagoons. Small lagoons or parts of larger but narrow la-goons should be covered by large panels shortening the installation period essentially. Large lagoons should be covered by single but longer geotextiles. A lot of projects worldwide show that each sludge lagoon is unique. Each project had its own specifics regarding geology, products and construc-tion. Furthermore the experience is that most of the building contractors are doing the job for the first time and even though they are guided as good as possible during design and construction, there al-ways is a process of learning by doing, changing and optimizing the original design.