On 20 February 2016, Vladimir Putin held a working meeting with the Head of the Altai Republic, Alexander Berdnikov, during which the future of the artificial lake in the Altai Valley tourist zone was discussed. Last year, activists from the All-Russia People's Front told the President about the inefficient use of funds at this site and problems with filling the lake.
The article examines the design and construction problems of this hydraulic structure, the chronology of events and possible ways to resolve the issues.
Abstract.
The Altai Valley, later renamed the Valley of Altai, is a special economic zone for tourism and recreation in the Altai Republic, established under a resolution of the Russian Government dated 3 February 2007. The SEZ is managed by the Department of Special Economic Zones and Project Financing of the Russian Ministry of Economic Development, OJSC Special Economic Zones and its branch in the Altai Republic.
The Altai Valley is intended to develop health and wellness, skiing, environmental, water and adventure tourism. The resort's main feature was to be a heated artificial lake with a water surface area of 51 ha, since there are no warm bodies of water for swimming in the Altai Republic. The initial Altai Valley project was developed by the German company Roland Berger Strategy Consultants GmbH. The state expert review then approved a completely different project by the Novosibirsk company Water World. Further changes were subsequently made to the project, and Megapolis was engaged to construct the facility as the general contractor. Then, in 2012, due to a change in the management of the special economic zones and the failure to complete the assigned tasks on time, the general contractor was replaced by OJSC Sibmost.
RemstroyMost LLC, headed by Alexey Dvoynichnikov, carried out further work and completed construction on an accelerated schedule, then began filling the lake. On 15 January 2013, the water level reached the design elevation, but it soon became clear that the lake was experiencing serious leakage, with the level falling by approximately 6 centimetres per day.
To determine the cause of the water leakage, OJSC Special Economic Zones engaged the B. E. Vedeneev All-Russian Research Institute of Hydraulic Engineering. The institute conducted studies to identify the causes of leakage at the artificial lake construction site and provided recommendations for eliminating it. The study included a comprehensive analysis of the design documentation and documentation for the work actually completed, as well as work to identify the locations and causes of filtration in the seepage-control liner. The research report contains complete information on the condition of the seepage-control liner's structural elements in the sections of the artificial lake slope exposed during June–July 2013.
To examine the situation in greater detail, we invited one of the participants in the construction process—the ge membrane supplier and Commercial Director of TechPolymer Group, Sergey Putivsky, to act as an expert.
In your opinion, what is the main cause of the situation with the lake?
It should be noted that it is not possible to identify one specific cause of the lake's leakage. In our view, a number of serious errors were made both during the design and construction of the facility, resulting in such a poor outcome. These included a poor design solution, changes subsequently made to the project, such as changing the thickness and type of geomembrane, and poor-quality work, the consequences of which are shown in the report's photographs.
However, the primary cause of all the problems was the poor-quality design. It should be noted that the company Water World, which prepared the artificial lake project, including the seepage-control liner, had no previous experience designing hydraulic structures of this scale. Nor did the contractors directly involved in installation. As a result, a number of errors were made, such as failing to provide cushioning layers to protect the geomembrane from being pushed through during construction. Experience in designing similar structures is essential for properly implementing the design solution and carrying out subsequent work.
In our view, one of the main causes of the situation was the accelerated construction schedule, which led to violations of installation standards, the geomembrane being pushed through by machinery, poor subgrade preparation and careless backfilling of the material.
An entirely unacceptable error was the attempt to save costs by irrationally replacing the seepage-control liner materials and reducing their thickness.
Which materials were replaced and why?
The contractor Megapolis changed the type and thickness of the geomembrane specified in the project: the approved LDPE (ПЭВД) geomembrane with a thickness of 1.50 mm was replaced with an HDPE (ПЭНД) geomembrane with a thickness of 1.00 mm. When making the change, only tensile strength was considered out of the many relevant characteristics. This property is the same for these types of geomembrane, but other important factors were overlooked, such as construction-period risks, puncture and push-through.
At the meeting with V. V. Putin, the regional head mentioned using clay to repair the leak*. In your opinion, will this solve the problem?
This solution was studied during the project-development stage, and an economic and scientific justification was provided in favour of an artificial geomembrane seepage-control liner over a clay layer. It is unclear exactly how the lake bottom will be “filled” with clay; the project is not publicly available, and the results of these studies have not yet been presented.
- We have found a solution; there is a design solution. It is now being completed. We will no longer lay film, as this is very costly and has no prospects; instead, we will “fill” the lake bottom with clay. Such technologies exist, we have good, high-quality clay, and all tests have been carried out.
What recommendations are given in the report by the B. E. Vedeneev All-Russian Research Institute of Hydraulic Engineering?
The report considers two options for strengthening the seepage-control structure of the lake bottom: using bentonite mats or clay as the main seepage-control element. It should be noted that the report specifies the need for additional calculations to substantiate the solution. In our view, the use of bentonite mats involves a high risk of leakage, since the material is laid with overlaps and the installation technology does not provide for welding; accordingly, the liner is not watertight. Given the scale of the hydraulic structure, other design solutions should be sought.
What solutions to the problem do you see?
We see the solution to such problems in the use of multilayer seepage-control liner systems. In this specific case, given the limited material resources, a two-layer system could be used: the subgrade is prepared, a bentonite mat is laid on it, the next seepage-control layer is made of geomembrane, and the area is then backfilled with sand. This design protects the geomembrane from mechanical impact, including the movement of machinery. The bentonite mat serves as a backup waterproofing layer for the main seepage-control liner and can localise leaks if the film is nevertheless damaged.
