There are several user inputs the program will use to compute the pipe system layout. These are found on the SYSTEM tab: (figure 5.)
Units of Measure:
Choose between Imperial (US Customary) or Metric
User may choose between one of the pre-loaded layouts and designate the outlet location if applicable. Although the program is limited in its layout configurations, one option for the output file is a DXF file which will allow the user to manipulate the layout of the system in AutoCAD®.
With this drop down box the user may choose to have headers at both ends of the system or only at one end.
Under this drop down the user will find "Plain End – Soil Tight" and "Gasketed – Water Tight". The first option will give you plain end fittings and ADS N-12® ST-IB pipe with ASTM F477 gaskets. The fittings will be joined to the pipe using split band couplers. The second option will give you bell end fittings and gaskets as was as ADS N-12® WT-IB pipe. All joints in this option meet the requirements of ASTM D3212.
Design Storage Volume:
Enter the required storage volume needed to be contained within the
Total Possible Length:
Enter the length of the available footprint. The program will maximize this input variable so as to minimize the system width, reduce the number of fittings and therefore produce a least cost system layout.
Total Possible Width:
Enter the width of the available footprint from your project site.
X Axis Slope:
If desired enter the slope of the pipe runs.
Typical values are 0 – 0.005 ft/ft
Y Axis Slope:
If desired enter the slope of the manifold header.
Typical values are 0 – 0.005 ft/ft
Include Header(s) in Storage Volume:
There is considerable less storage volume in the manifold header than in the rest of the pipe system; so much less some designers neglect its contribution while others included it. The program allows the user to include or exclude the storage contribution from the manifold header in the total storage volume.
If one is designing a perforated retention of detention system then click this box to perforate the laterals. The program will not allow the user to select perforated laterals and water tight pipe.
The BACKFILL tab contains an illustration of a typical pipe cross-section with important nomenclature the user needs to be aware of. Also on this tab the user can input elevation and fill height information. (figure 6.)
Average Cover Height:
Input the average cover height over the system. Maximum cover height for all systems is 8 feet. In traffic application the minimum cover height for 12" – 36" pipe is 12", for 42" – 60" pipe the minimum fill height is 24". In traffic applications cover is measured from the crown of pipe to the bottom of flexible pavement or to the top of rigid pavement. Minimum cover height in non-traffic applications is 12".
Input the elevation of the outlet of the detention system. The system defaults to 0 feet
Finished Grade Elevation:
Input the approximate average finished grade elevation. An error message will appear if the no available pipe size will fit within the constraints.
If the user has chosen to design with perforated pipe, they may adjust the stone porosity. Typical values range between 30 and 40%, however the final value here should be chosen based on input from a competent geotechnical resource. When designing a perforated system, the storage in the system includes the storage from the pipe as well as storage in the stone.
The program calculates the stone storage to include the pipe bedding up to the crown of the pipe.
Additional Stone Layer:
When designing with perforated pipe, if so desired, one can increase the storage capacity of the system by increasing the bedding thickness, this is done by adjusting the ASV (additional stone volume). The width and length of the ASV is the system footprint and so the stone volume is determined by the thickness chosen in this field. The additional storage volume is then determined by multiplying the additional stone volume by the stone porosity.