
2018 Indiana Design and Installation Manual
26
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4.2 Sloped Subsurface Bed Design Installation Steps
1. Ensure all components leading to the GSF system are installed properly. Outlet filters are required with the
GSF system. Connections of lines to tanks and distribution boxes must follow requirements of 410 IAC 6-8.3
or ISDH Rule 410 6-10.1.
2. Determine the number of GSF Modules required using Table 5.
3. Prepare the site. Do not install a system in saturated ground or wet soils that are smeared during excavation.
Keep machinery off infiltrative areas. Refer to IAC 6-8.3 or ISDH Rule 410 6-10.1, for all site preparation
requirements prior to site construction.
4. Plan all drainage requirements above (up-slope) of the system. Set soil grades to ensure that storm water
drainage and ground water is diverted away from the system once it is complete. All drainage requirements
shall be in accordance with 410 IAC 6-8.3 (59).
5. Excavate the bed basal area; scarify the receiving layer to maximize the interface between the native soil and
specified sand.
6. Minimize walking in the basal area prior to placement of the specified sand to avoid soil compaction.
7. Place a minimum of 6 inches of Specified Sand in the basal area and stabilize level. The first 6 inches of sand
immediately under and around the perimeter of the GSF system must be
INDIANA DEPARTMENT OF
TRANSPORTATION (INDOT) SPECIFICATION 23 SAND.
See Table 1 for more information on the sand and
sieve specifications.
8. Place GSF modules with
PAINTED STRIPE FACING UP.
Each row of modules is laid level in its length and
width, end to end, along their four-foot length on the Specified Sand layer. No mechanical connection is
required between modules.
9. A standard 4-inch perforated pipe, SDR 35 or equivalent is centered along the modules 4-foot length. Orifices
are set at the 4 & 8 o’clock position.
All distribution piping must meet the requirements of ISDH Rule 410 6-8.3
Section 67 or ISDH Rule 410 6-10.1 Section 75.
10. All 4-inch pipes are secured with manufacturers supplied wire clamps, one per module.
11. (Pressure Distribution Systems) Insert a Sch. 40 pressure pipe which meets 410 IAC 6-8.3 (67) or ISDH Rule
410 6-10.1 (75), into the standard 4-inch perforated pipe. The pressure pipe orifices are set at the 12 o’clock
position as shown in Figure 26. Each pressure lateral will have a drain hole at the distal end of the lateral at
the 6 o’clock position. Each pressure lateral shall have a clean out at the end of the row.
12. The distribution pipe shall be capped or vented.
13.
Cover fabric substitution is not allowed.
The installer should lay the Eljen provided geotextile cover fabric
lengthwise down the row, with the fabric fitted to the perforated pipe on top of the GSF modules. Fabric should
be neither too loose, nor too tight. The correct tension of the cover fabric is set by:
a. Spreading the cover fabric over the top of the module and down both sides of the module with the
cover fabric tented over the top of the perforated distribution pipe.
b. Place shovelfuls of Specified Sand directly over the pipe area allowing the cover fabric to form a
mostly vertical orientation along the sides of the pipe. Repeat this step moving down the pipe.
14. Place 6 inches of Specified Sand along both sides of the modules edge. A minimum of 6 inches of Specified
Sand is placed at the beginning and end of each module row. A minimum of 12 inches of Specified Sand is
placed in between module rows.
Содержание GSF A42
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