
2018 Indiana Design and Installation Manual
34
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5.2 Elevated Sand Mound 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 mound dimensions using Table 7.
3. Prepare the site. Do not install a system on saturated ground or wet soils that are smeared during excavation.
Keep machinery off infiltrative areas. Refer to ISDH Rule 410 6-8.3 Section 86 or ISDH Rule 410 6-10.1 Section
94.
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) or 410 6-10.1 (63).
5. Scarify the basal layer to maximize the interface between the native soil and Specified Sand. Minimize walking
on the receiving layer prior to placement of the Specified Sand.
6. Place Specified Sand in two 6-inch lifts, stabilize after each lift. The stabilized height below the GSF module
must be level at 12 inches. The first 12 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. Refer to ISDH Rule 410 6-8.3 Section 87 or
ISDH Rule 410 6-10.1 Section 95.
7. Place GSF modules with
PAINTED STRIPE FACING UP
, level in its length and width, end to end, along their
four-foot length on the Specified Sand layer.
8. 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.
9. All 4-inch pipes are secured with manufacturers supplied wire clamps, one per module.
10. 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 trench.
11.
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.
12. Place a minimum of 12 inches of Specified Sand along both sides of the modules edge. A minimum of 12
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.
13. Complete backfill with cover soil material to a minimum of 12 – 19 inches measured from the top of the 4-inch
distribution pipe. Fill must be clean, porous and able to sustain vegetation. Do not use wheeled equipment
over the system during backfill operation. A light track machine may be used with extreme caution, avoiding
crushing or shifting of pipe assembly.
14. Divert surface runoff from the system. Finish grade to prevent surface ponding. Topsoil and seed system area
to protect from erosion. All drainage requirements shall be in accordance with 410 IAC 6-8.3 (59)