Repairing Mumbai's crumbling drainage system 14 Feb 2013
Shotcrete Technologies News Release
- In July of 2012 Shotcrete Technologies Inc (STI) was contacted by Michigan Engineers Ltd of India to provide technical expertise, training and robotic shotcrete systems to rehabilitate portions of the aging storm water system in Mumbai.
Shotcrete Technologies supplied robotic systems
- The Indian metropolis with its millions of inhabitants, has been experiencing numerous failures of its century-old plus storm water system. Badly collapsed areas have affected traffic during peak hours, and bursting sewer pipes have created further cave-ins with disastrous effects. The old brick-lined system is badly in need of preventative maintenance, repairs and reconstruction.
- The first phase of this massive project identified particular areas to be repaired - mainly storm water drains and sewer lines that require urgent preventative attention before they fail. The most common problem is leakage within the system causing erosion or the sewer lines choking up, culminating in a road collapse sinkhole.
- Other goals of the project are delinking sewer and storm water systems to reduce coastal pollution and environmental hazards that are created when flooding occurs under the current drainage system.
- Michigan Engineers Of Mumbai was awarded an initial contract to rehabilitate 16 different sizes and shapes of storm water tunnels near the central rail station in old Mumbai. The pipes range in diameter from 1.5m to 4.5m and are of various shapes including oval, horseshoe, round and box culverts, with lengths varying from 16m to 2,400m. Specifications called for a shotcrete lining from 50mm to 200mm thick with a total 20,000m3 of shotcrete to be applied.
- The variety of shapes and sizes and challenging site locations called for a versatile application method, that was cost-effective, simple to operate, mobile and relatively foolproof.
- To meet the needs of the client, Shotcrete Technologies provided three Shot-Tech Robotic Arms, one Model 350, and two Models 160, and one Robotic Shotlining system. These would provide the most flexibility and cover the necessary range of shapes, sizes and lengths. Transcrete concrete pumps were chosen for shotcrete delivery through 2in hoses. To complete the system, locally sourced carriers were used to mount the robotic arms.
- To keep costs as low as possible, STI sent technicians to the site from its headquarters in Colorado, USA, and advised Michigan management on what types of carriers would be suitable for each unit, and what types of locally fabricated parts could be used. As much material and equipment as possible was sourced locally.
- Once the shotcrete units were delivered STI technicians assisted Michigan engineers in mounting the units on the various types of carriers, and after crews were trained, shotcreting began in earnest.
- The 40MPa sand mix with 10% silica fume was designed to pump more than 100m to the nearest manhole, and re-pump another 60m to the nozzle. Concrete delivery was challenging. During the day, traffic on the streets, both pedestrian and vehicle, is so congested and concrete delivery is nearly impossible. To solve that issue, work is now only performed at night between 9pm and 7am. With the proper mix, the shotcrete is often pumped hundreds of meters at a time.
- As anticipated, the Shot-Tech robotic arms and system are proving their versatility and productivity in extremely challenging conditions.
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