General question.

Discussion in 'Homeowner Assistance Forum' started by geotexZ71, May 21, 2005.

  1. geotexZ71

    geotexZ71 LawnSite Member
    Posts: 2

    Hello! I stumbled onto this website doing some research on residential irrigation systems for my own home and decided to look into this forum as I've done hundreds of wall designs and provided countless recommendations for subgrade preparation and construction for all sorts of paving and I am always curious what the contractors are doing. Yes, I'm a licensed engineer, and practice structural and geotechnical engineering in the States of NY, NJ, PA, DE, and MD. I also have about a half-dozen regular hardscaping contractors as regular clients.

    Anyway, in reading some of the questions and responses here, in particular those pertaining to retaining walls, I was left with an unsettled feeling due to the seeming lack of understanding and knowledge about building codes, design, and construction of walls... I am curious how often some of you consult with an engineer, whether a private engineer or one who works for the manufacturer of the segmental products you may be using? Also, how many of you rely solely on the local code officials for requirements versus verifying the building code yourself because height is only one discriminator in the need for design in most of the codes? How about inquiring about suitability of backfill - e.g., clean 1" minus material is not necessarily the best choice for backfill when the native soil is a fine sand and silt.

    I'm not here to bash, nor do I mean to intrude. I'm sincerely curious and wonder if we engineers should be marketing hardscapers more to promote better understanding for the need for good design and/or site-specific construction recommendations. True, for the professional engineer such work is small potatoes, but I know I like the work for my younger engineers to develop on and it makes a decent filler between the money work.
     
  2. Grass Masters

    Grass Masters LawnSite Member
    from NC
    Posts: 85

    On small jobs no BUT if I have a job that is over 4 foot tall (WALLS) I do consult and Enginner
     
  3. P. Baxter

    P. Baxter LawnSite Member
    Posts: 24

    We have not consulted an engineer for any of our projects, in most cases residential homeowners do not want to pay for the services. We have built some very large walls in our area, and when we do we always use the spec sheets from the manf. To this day we have not had any problems, we may also over build the wall because there are no engineer spec on the project.
    I think it would be good for more engineer's to let Landscape companies know there services in this field, as long as they are geotextile certified.
     
  4. geotexZ71

    geotexZ71 LawnSite Member
    Posts: 2

    Sounds like we engineer's, and segmental manufacturers, need to do a better job educating wall contractors. Unfortunately, the mechanisms of wall failures are often very slow but result in sudden failure - anyone see the news on the turn-of-the-century wall in NY that fell? I would urge wall contractors to seek out an engineer and establish a relationship if you commonly construct tall walls or deal with difficult soils or retain soils with obvious seepage regardless of what the homeowner wants. It is for the protection of you both. Our fees can be quite small compared to the potential liable.

    As for geotextile-certified, that's a little bogus as far as credentials go. Geotextiles are one facet of a much larger group of synthetic engineering materials collectively called geosynthetics. I personally was a graduate student to the father of geosynthetics, Dr. Bob Koerner, and have been working with them for over a decade. Most any geotechnical design engineer in practice today is familiar with them, and it's really our willingness to put our professional seal, our license, on our design recommendations that should be your gauge... I have designed 5-foot segmental walls to 45-foot mechanically stabilized earth embankments for highways to 125-foot wrap walls, which are geogrid reinforced - the big brother to geotextiles, retaining 300+ feet of landfilled waste.

    As much as building walls are an art, they are also a science.
     
  5. P. Baxter

    P. Baxter LawnSite Member
    Posts: 24

    GeotexZ71 we are located in the Rochester, NY area, do you do any work up this way????? If you do I would be intrested in consulting with you if we do get any larger walls in the future. Although there is a huge company in the area that has built large walls 1 that was designed by an engineeer blew out befor they even finished the job HMMMMMMMMMM, could be bad contracting.
     
  6. fall46

    fall46 LawnSite Member
    Posts: 141

    Per your post u seem to be extremely versed into the science behind the construction of retaining walls. That being said Iam not a contractor but rather a homeowner who has constructed some paver patios and a couple of small retaining walls... One aspect though has left me somewhat confused. That is how deep (wide) does one backfill with clean minus behind the wall relative to its actual height... I have heard minm 12'' wide by 12'' tall and other times within 6'' of the top of the wall. My neighbor and I are constructing a wall that is roughly 30 '' in height. I have also heard various opinions on wrapping geotextile fabric around the stone.......some say that it will eventually fill with silt dirt etc effectively becoming a barrier thus exerting hydrostatic pressure others seem to say just the clean fill will safice
    ......The soil is somewhat clay in nature and the grade of my property slopes toward the wall.

    Any insight into these issues would be most appreciated
     
  7. P. Baxter

    P. Baxter LawnSite Member
    Posts: 24

    who r u asking????
     
  8. fall46

    fall46 LawnSite Member
    Posts: 141

    Geo ,,,,,but I welcome anyone's response or insight P Baxter
     

Share This Page