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Recent content by lsp01

  1. lsp01

    ôQoutö greater than æQinö in ICPR

    Xghalibx, I don't understand your model, if the normal water level (NWL) in Pond 1 is 936.5 and the NWL in pond 2 is 935 ft, why would you expect the water to flow up gradient? Pond 2 would have to stage up 1.5 feet to induce flow back into Pond 1. Could it be just discharging to the outfall...
  2. lsp01

    high water table

    Johnhan76, I have to agree with Gjeppesen, sometimes it is less costly to just fill instead of excavaiting the road. You will probably run into dewatering issues considering the water table. If you are in Florida, dewatering also requires a permit from the local Water Management District and...
  3. lsp01

    drainage ditches in coastal areas

    Gumhead, When I was designing some stormwater improvements in an older neighborhood in south Florida we had a very similar situation. The problem was not really flooding into homes etc, just nuisance water in the yards and roads. In this instance the area had already installed roadway piping...
  4. lsp01

    ICPR manual

    Cimmeron, I've used ICPR for years and have found it to be a very stable and easy to use program. It is very intuitive regarding its layout. If you are familiar with stormwater modeling (eg BRN or Haested) you will have no problems. I think the problem that you are running into is that the...
  5. lsp01

    ôQoutö greater than æQinö in ICPR

    xghalibx, I believe that you've run into one of ICPR's limitations, the program does not model pipe runs very well, unless they act as equilizers. You will get more reasonable results if you remove the pipe system from the model and add the pipe system drainage area to the closest pond (Pond...
  6. lsp01

    ôQoutö greater than æQinö in ICPR

    xghalibx, The mass balance report indicates the model's stability. If you have large fluctuations in the mass balance, the model is unstable. Normally, there may be a small fluctuations in the first few iterations, but it should go to zero % error well before the end of the model run. If...
  7. lsp01

    "C" for wetlands

    I agree with cvg, In Florida I've come across two different schools of thought regarding wetlands. Use a high C of 0.9 or 1.0 but allow for some storage (hard to do with the rational method) or estimate a relative C and adjust the Time of concentration. Open water wetlands (standing water)...
  8. lsp01

    ôQoutö greater than æQinö in ICPR

    Hi, I have a couple of thoughts.... 1. Remember that Q in cfs is a rate not a volume, what is the slope in the pipe? 2. Is the model valid? Have you checked the mass balance? You maybe losing water from your system. 3. Check the peak stage information at the junction nodes, I know that...
  9. lsp01

    IDF constants

    As a stormwater engineer in Jacksonville for over 8 years, I can safely say that we don't use the FAA method. You need to contact the St. Johns River Water Management District (www.sjrwmd.com) and get a copy of the design manuals. Florida has many requirements that other states do not...
  10. lsp01

    Submerged Outfall

    In our local tidal areas, we have frequently had a problem with some inlets flooding due to unusually high tides or storm surge. (This can really be a problem if it's salt water and asphalt pavement!) We have found some success with the installation of tide flaps at the outfall or at a large...
  11. lsp01

    plastic pipe

    Just a note.... Don't forget about structures, inlets, catch basins and end sections that will act to secure the pipe. I work in an area with very shallow water tables (Florida) and there is seldom a problem if the structures are not too far apart. Just be careful during construction. Laura P...
  12. lsp01

    Draw down radius through clay barrier

    I am trying to find an accepted method of calculating the draw down radius associated with a stormwater pond having a controled discharge set below the accepted groundwater table. We are trying to reduce potential wetland impacts due to the lowering of the water table by introducing clay...
  13. lsp01

    IDF curves HELP

    Depending on where your are, most DOT or Flood Control Districts have established IDF curves for their respective areas. In Florida the FDOT publishes them in a drainage manual and also provides formulas to approximate the curves. I understand that Georgia and N. Carolina do the same Laura P, PE
  14. lsp01

    French Drain

    To PECPESC In the areas that I have practiced (California & Florida) the term "french drain" is usually used to describe a drainage system that has no discharge except through percolation. We have also described them as exfiltration trenches. The gravel is very useful in increasing...
  15. lsp01

    French Drain

    Yes there will be a problem! The purpose of a french drain is to hold runoff and allow it to percolate into the surrounding soil. When sizing a french drain you calculate the available storage using both the pipe and the voids in the gravel. If you eliminate the gravel, the system will not...
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