The DTA gasification complex wastewater treatment facility includes pre-treatment section, biological treatment section, and tertiary treatment section. Each discipline had unique challenges while executing engineering of this project. The complex process with multiple treatment technologies under one roof, compressed plot area accommodating huge civil units and equipment, challenges in civil footings due to compressed layout, huge structures, variety of piping work and the quantum of electrical and instrumentation work. This profile describes the complexity of project engineering executed with the support of technology tools and experience.
The system consists of Pre-treatment section (Cyanide Removal, Iron Removal, Fluoride Removal, Heavy Metal Removal, Chemical Sludge treatment), Biological Section (Two stage aeration system, Biological Sludge treatment), Tertiary treatment Section (Ultra filtration and Reverse Osmosis). WES has handled civil portion of this project which includes 650 tonnage of structural steel, 2400 tonnes of Re-inforcement Steel,Re-inforced Cement Concrete of 24200m³. One of the most critical challenges faced while designing civil structures was the design of pipe bridge footing where space was a constraint. The huge civil tank for clarified water storage (84.5×12.75), with its raft coming in the way of column footing of bridge was a challenge with respect to foundation of bridge. Conventionally such foundation footings are done with combined footing, as this consumes a lot of concrete. With our expertise we designed it for combined strip footing which consumes concrete much less as compared to combined footing. Overall considering steel and concrete together the average saving is around 20%. This design is a composite methodology viz. combination of combined footing and stripped beam leading to combined strip footing.
The third one was the critical design of structural bridge for pipes and cable trays. You can see the snap of a structural bridge as below. The design involved 21 load cases for which the structural analysis was to be carried out. Main loads comprised dead load, Pipe frictional load, Wind and Seismic load in various directions, test load etc. The structure is about 15 m in height. The analysis was done using STAAD-PRO software.
Fourth case was for RO shed, here we used prefabricated plated sections of structural members over the conventional structural members. Here the saving in kg/m2 was approximately 50% against the conventional structures. The plated sections are having variable cross sections with respect to its length. This helps in maintaining the cross section comparative to the load reducing the total weight.
The entire piping model is done in PDS software. Stress analysis of high pressure piping in duplex and non-metallic GRE piping is done using Caesar to take care of adequate supporting and stress proof pipe routing. There were around 1250 plus isometrics with materials like GRE, CS, GI, SS, Duplex, CPVC, etc. Total piping is around 27km in length. Pipe sizes range from 15NB to 600NB and the total inch dia. of 52000 and inch meter of 60000. Although there was a space constraint, special care was taken from ease of operation and maintenance point of view.
Valves sizes ranging from 50mm to 450mm with wide range of material of construction like UPVC, PP, Carbon steel with both lined and unlined types, SS 316L, Brass and Duplex stainless steel. The quantity of valves is around 3000 nos. with pressure class upto 800 pounds.
DTA electrical works involved around 330 km of power and control cabling. With 286 motors for different duties ranging from 0.37kw to 132KW out of which 48 nos. are with variable frequency drive. The complexity of cable routing can be seen in above snap containing a 9 meter high cable rack containing 22 no. of power and control cables trays.
There are about 550 number of instruments with various types of analyzers (Ph, ORP, Dissolved oxygen, Cyanide, Flouride, Nitrate, etc). These were special analyzers and were used rarely. Special care was taken while doing the selection of these analyzers. This also demonstrated our capability to do something new with additional efforts right first time.
Instrumentation: In tools (an Intergraph software for instrumentation and control) was used for this project. IN tools is integrated software for control and instrumentation. All engineering data sheets are to be made through In Tools. The software is such that any change in any of the data sheet will automatically update the respective documents for eg. any change in instrument details once updated will get automatically updated in Instrument index, I/O list.