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Utility Layout - Road and infrastructure Project

  • 1.  Utility Layout - Road and infrastructure Project

    Posted 10-30-2017 12:45 PM
    Hello all!

    I currently  involved in a Roads and infrastructure Project.

    The Proposed layout has 16 trenches with 12 utilities at various depths ranging from 1.5  to 9 meters. 

    The terrain is black cotton soil which needs to be disposed off. The depths range from 1.2 to 2.6 meters.

    Question: what should be the method of execution?

    1) Should I remove the black cotton soil, complete the utilities, backfill and move upwards to formation and finish levels?


    2) Should I remove the black cotton soil, backfill using recommended material, excavate for the utilities, and proceed to formation and finish levels on utilities completion?

    Would appreciate inputs from fellow engineers...

    Kalyan Emandi
    Sr.Project Engineer


  • 2.  RE: Utility Layout - Road and infrastructure Project

    Posted 10-31-2017 05:03 PM
    ​Since the 'black cotton soil needs to be dispose of' (I' assuming you mean excavated and removed). I would excavate and remove the 'black cotton soil' first as that would lower your overall depth of excavation for your utilities. Install the utilities, backfilling and compacting the trenches as required. Then construct your subbase and/or base  and road surface.

    John Levitt P.E., M.ASCE
    Grapevine TX

  • 3.  RE: Utility Layout - Road and infrastructure Project

    Posted 10-31-2017 05:04 PM
    These comments assume we are talking about a road project and not a building structure project:
    Removing that volume of highly expansive "cotton soil" will add significantly to the cost of the project.  Moreover, suitable replacement soil is often difficult to obtain and incur significant hauling costs.  There are chemical treatments for montmorrillinite soils (cotton soils) that significantly reduce the permeability of the soil, sometimes by an order of magnitude, and increase the bearing capacity of the soil.   The one I am familiar with uses sulfuric acid, limonene oils and soap.  Aluminum silicate is soluble at both high and low pH.  The process acts in cotton soils to form Calcium sulfate (gypsum), aluminum sulfite (flocculant) and acts as a sulfonated oil compound which reduces the permeability of the soil.  These treatments (depths of 8 inches) typically have an in-place cost of about 50% of lime treatment as remixing is not required.  Strength increases over time as the pH of the subgrade moves toward neutral due to the natural pH of the soil and compaction water.   It is important not to introduce water below treated soil via poorly jointed storm drains.  Utility bedding material often acts as a conduit for moisture.  If the cotton soil is treated rather than removed, the road would typically be brought to finish grade prior to utility excavation.

    James Anderson P.E., M.ASCE
    Project Engineer
    North Richland Hills TX

  • 4.  RE: Utility Layout - Road and infrastructure Project

    Posted 10-31-2017 05:07 PM
    ​wow, I would love to see what a black cotton soil sample....

    Josue Montes G.E., P.E., M.ASCE
    Smith Emery
    Fresno CA

  • 5.  RE: Utility Layout - Road and infrastructure Project

    Posted 10-31-2017 05:08 PM
    Your second option is preferred.  As you remove the "black cotton soil", remember to go beyond the edge of road to laterally support the utilities that are near the edge, and to provide lateral support to the road itself.  By bringing the roadway up to the subgrade, you can place and compact the replacement soil using larger equipment.  When the utilities are excavated for, the installation will go faster using the subgrade as your guide, and having solid soil to compact against.  This trench compaction is critical in preventing your new roadway from having a wavy cross section only a few years down the road as poorly compacted trenches settle.  Remember to place the deepest utilities first and work your way upward so you do not undermine the shallower pipes.  Do not place the shallow pipes in the area of influence of the deeper pipes if you can avoid it.  One final note, if there are to be utility connections to adjacent properties, keep in mind that the boundary between the "black cotton soil" that remains outside the roadway, and the replacement soil will add stress points to the lateral connections.  You will need to account for this in your design.

    Mario Ricozzi P.E., F.ASCE
    Manager of Design
    Greater New Haven Water Pollution Control Authority
    New Haven CT

  • 6.  RE: Utility Layout - Road and infrastructure Project

    Posted 10-31-2017 05:08 PM
    ​Greetings from California,

    I would be interested to see "plans".  For example, I'd like to better understand the configuration of these deep trenches (those at 9m especially).

    What is going in these trenches?  Can these utilities withstand any settlement/expansion?

    I'd especially be interested to learn the scale of the project...

     I'd also like to understand the available work-room, terrain to see how this problem could be attacked--and how we could judicially waste this black cotton say using a scraper-haul, in a manner that won't create a mess for others.

    Do you have "good"  Geotechnical info which allowed you to determine the depths of the black cotton?

    Next--what kind of equipment do you have available?   As we get into those 2.6 meter depths, I envision we're likely going to need some decent heavy equipment if we building a lot of road.

    How will the roadway surfaces be paved?  What is the terrain?  What does do the drainage systems look like?

    All-in-all I'd suggest we look at the project as a whole--the black cotton is one nasty component; hopefully the worst.

    Scott Onishuk P.E., M.ASCE
    Santa Barbara CA

  • 7.  RE: Utility Layout - Road and infrastructure Project

    Posted 10-31-2017 05:09 PM
    This seems like a coordination question because of the large number of trenches, the depth of the utilities and the fairly large quantity of off- haul.  If you are on the contractor's team, (and therefore responsible for means and methods) close coordination with your field staff will be essential. The coordination would include, at least, access, slope (if any,) haul roads, material staging and placement, and equipment movement. 

    Either sequence shown in your question might be right for one part or the whole part of the project.  The answer lies in the coordination of a team of performers. 

    Your question is a question about your team building skills, because size of the project is going to require the coordination of a three-ring circus.  The way to get it built is creating buy-in from a team.  Engage a team, listen to them, require them to listen to each other and buy-in to a plan.  Read about pull-planning in Lean Construction Institute materials.  Great question.  Best to you.  
    John Donley 

    John Donley A.M.ASCE
    Donley Construction Consultants
    Los Angeles CA

  • 8.  RE: Utility Layout - Road and infrastructure Project

    Posted 11-01-2017 10:41 AM
    I recommend you read ASCE publication 60.  This will prepare you for deep pipe construction.  If you have flexible pipe the deep pipes will be impacted by which sequence you use. In a standard trench the pipe will deflect as loaded and as the trench settles. As the soil within the trench drops an arching effect and backfill dragging on the sidewall of the trench will prevent part of the load from transferring to the pipe.  Embankment conditions will place more load on a flexible pipe.  For this reason you need to place the fill first and then excavate.  However, if you  can take additional load on the pipes based on depth or increased wall thickness their is an advantage of having no trench penetration of your paving as pipes settle. You are less likely to have cracks in your paving as you will have a thick monolithic soil that is uniform under the paving.

    In addition it may make retrenching for future main replacement more stable as you will not have close parallel full depth excavations.  This is assuming you have very controIled  fill. 

     I would not count on this for shorring design for subsequent repair.  You should consider in all designs future maintenance.  Deep pipes will require more right of way for shorring safety.  Consider placing dry utilities in a common duct structure.  

  • 9.  RE: Utility Layout - Road and infrastructure Project

    Posted 11-06-2017 02:13 PM
    Dear All,

    Apologies for not replying earlier.  A huge thank you for the suggestions and inputs. Really appreciate the suggestions.

    I have been working on the Black cotton Soil for the last few days. 

    1.  Barbara Salvini : Thank you for the inputs. How do I get ASCE publication 60. Do you have a link? I am working on it. Will get back to you for more insights.
    2. John Donley: Absolutely spot on Sir! Thank you . I am currently reading about Pull Planning. My take so far on it is to use both the strategies with two teams. The best outcome shall be followed . This is quite a challenge to convince as this will test my team building and communication skills. Will be back for more suggestions from you.
    3. Scott OnishukWe have 16 Trenches with 12 Utilities. The width of the entire cross section varying from 24 to 40 meters. Dual carriage and single carriage. Most of the utilities are placed under the road . 6 Wet utilities ( Storm water, potable, treated etc) and 6 Dry utilities ( Electrical, signalling, street lighting, etc). I am working on the disposal of the waste , ideally coming up with a good strategy on it- but for the moment- I am still working on it. Equipment  Excavators, Loaders , Trucks , back hoes . Geotech report is good, 3 different labs used. Max depth is 3 and   minimum is 2 meters.
    4. Mario Ricozzi : Thank you. Very valuable suggestions . I will definitely come back for more suggestions from you.  
    5. James Anderson: Thank you. I am working on chemical treatments but I am on a sticky wicket, need some time to convince the Client.
    6. John Levitt: That's the regular sequence we are planning. But I had my doubts with the Black cotton soil. Will update on the procedure in due course of time. Thank you.

    Kalyan Emandi
    Sr.Project Engineer

  • 10.  RE: Utility Layout - Road and infrastructure Project

    Posted 11-07-2017 10:55 AM
    Kalyan:  I believe this has been replaced by this journal which can be found on the ASCE web site under publications/journals. You might want to contact someone in publications to be sure.  
    Barbara A.B. Salvini, P.E. 
    Barbara A.B. Salvini Engineering

  • 11.  RE: Utility Layout - Road and infrastructure Project

    Posted 11-06-2017 02:13 PM
    Dear All,

    Please accept my apologies for the delay in replying. I am absolutely overwhelmed with the variety of responses and comments I received.

    I was reading the replies , but wanted to reply in a reasonable manner rather than just reply for the sake of it. 

    Replying in 

    Barbara Salvini:
    Thank you. Very good point I haven't thought on those lines. I was looking for ASCE Publication 60. Unable to find it. Is there a key word I have to type to find it.  

    John Donley: Absolutely. I am exactly at that juncture . I have started reading on Pull Planning, Thank you for the head's up. I really appreciate your input.
    Currently I am mentoring a team of engineers with Quantities , Planning and  Estimation.
    Ideally I'd like to learn as much as possible plus mentor the new engineers in the best possible way in this exciting Project without affecting the Project Progress i.e. Schedule & Cost.

    Scott Onishuk:
     Hello Scott,
    We have 16 trenches for 12 utilities. 
    6 wet utilities

    Storm Water
    Foul Sewer
    Industrial Waste water
    Industrial Treated water
    Potable water 
    Industrial effluent

    6 Dry Utilities:
    Fiber optic
    intelligent transport 
    Traffic signal
    Street lighting

    Mario Ricozzi:  Thank you for your inputs. i am keenly looking into your comment. will certainly come back with more.

    James Anderson :  I am reading on chemical treatments. Please share any particular system which you have used earlier. it will certainly give us a head's up. Thank you

    John Levitt: 

    I had similar thoughts. needed to have an open discussion to get to best possible solution. Than you for your input.

    Kalyan Emandi
    Sr.Project Engineer

  • 12.  RE: Utility Layout - Road and infrastructure Project

    Posted 11-07-2017 12:41 PM
    ​The Chemical treatment that I am familiar with is a patented process called Roadbond EN1.  It has a 30 year record in the Dallas/Fort Worth TX area where we have extensive smectite (montmorillinite) clays.  It was extensively tested at the Texas Transportation Institute in 1996  and outperformed both lime and several other chemical treatments.  Technical information is available on the Roadbond EN1 web site.  It has been used in numerous countries.  It can be used with both cement and fly ash or by itself.  The higher the Plasticity Index, the better the product works.

    James Anderson, MASCE
    Anderson Consulting
    North Richland Hills, TX

  • 13.  RE: Utility Layout - Road and infrastructure Project

    Posted 11-08-2017 10:07 AM
    Hello Kalyan,
    To me the problem seems easy to solve, or I may be unaware of the real situation you are facing!
    Its necessary to dispose off the black cotton soil first, then before refilling it's logical to complete your utilities laying out and then fill up to desired level with recommended materials.
    I hope it helps!

    Peter Singh M.ASCE
    Managing Director
    Kingdom Designers

  • 14.  RE: Utility Layout - Road and infrastructure Project

    Posted 11-09-2017 02:36 PM

    My expertise is buried pipeline.  If you can do trench, it is better than the other one.  The pipe in trench would carry less load than the one under embankment.  Two totally different design methods for two conditions.  I will suggest you fill and then excavate trench. Contact me for more help.


  • 15.  RE: Utility Layout - Road and infrastructure Project

    Posted 11-09-2017 02:37 PM
    Earth Science Products, Corp. has a soil stabilization product, Condor SS, that is based on Ion Exchange Technology. Condor SS treats a broad range of silt and clay soils. Ion exchange is an electro-chemical reaction that breaks the soil-water bonds that cause engineering design problems resulting from expansion/contraction cycles and poor sub-grade strength for roadways and buildings. Condor SS can be injected to treat the "zone of influence" not just a surface application. Condor SS provides a cost effective and environmentally safe soil stabilization solution when working with moisture sensitive soils. Visit earthscienceproducts.com for more information.

    Jeffrey Jensen Aff.M.ASCE
    Earth Science Products Corp
    Wilsonville OR