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17
4.0 Foundation for Chambers
4.1 FOUNDATION REQUIREMENTS
StormTech chamber systems and embedment stone may
be installed in various native soil types. The subgrade
bearing capacity and chamber cover height determine
the required depth of clean, crushed, angular stone for
the chamber foundation. The chamber foundation is
the clean, crushed, angular stone placed between the
subgrade soils and the feet of the chamber.
As cover height increases (top of chamber to top of
finished grade) the chambers foundation requirements
increase. Foundation strength is the product of the
subgrade soils bearing capacity and the depth of
clean, crushed, angular stone below the chamber foot.
Table 1
for the SC-160LP,
Table 2
for the SC-740 and SC-
310,
Table 3
for the SC-310-3, and
Table 4
for the DC-
780 specify the required minimum foundation depth for
varying cover heights and subgrade bearing capacities.
4.2 WEAKER SOILS
For sub-grade soils with allowable bearing capacity less
than 2000 pounds per square foot [(2.0 ksf) (96 kPa)],
a geotechnical engineer should evaluate the specific
conditions. These soils are often highly variable, may
contain organic materials and could be more sensitive to
moisture. A geotechnical engineer’s recommendations
may include increasing the stone foundation, improving
the bearing capacity of the sub-grade soils through
compaction, replacement, or other remedial measures
including the use of geogrids. The use of a thermoplastic
liner may also be considered for systems installed in
subgrade soils that are highly affected by moisture. The
project engineer is responsible for ensuring overall site
settlement is within acceptable limits. A geotechnical
engineer should always review installation of StormTech
chambers on organic soils.
4.3 CHAMBER SPACING OPTION
No spacing is required between the SC-160LP chambers.
StormTech requires a minimum of 6” (150 mm) clear
spacing between the feet of chambers rows for the
SC-310, SC-740 and DC-780 chambers. However,
increasing the spacing between chamber rows may
allow the application of StormTech chambers with either
less foundation stone or with weaker subgrade soils.
This may be a good option where a vertical restriction
on site prevents the use of a deeper foundation. Contact
StormTech’s Technical Service Department for more
information on this option. In all cases, StormTech
recommends consulting a geotechnical engineer for
subgrade soils with a bearing capacity less than 2.0 ksf
(96 kPa).
Cover Hgt.
ft. (m)
Minimum Bearing Resistance for Service Loads ksf (kPa)
4.4-3.8
(211 to 182)
3.7
(177)
3.6
(172)
3.5
(168)
3.4
(163)
3.3
(158)
3.2
(153)
3.1
(148)
3.0
(144)
2.9
(139)
2.8
(134)
2.7
(129)
2.6
(124)
2.5
(120)
2.4
(115)
2.3
(110)
2.2
(105)
2.1
(101)
2.0
(95)
1.0
(0.31)
3
(75)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
9
(230)
9
(230)
9
(230)
9
(230)
9
(230)
9
(230)
9
(230)
9
(230)
1.2
(0.46)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
1.5
(0.46)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
6
(150)
2.0
(0.61)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
6
(150)
6
(150)
6
(150)
2.5 to 9
(0.76 to 2.74)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
9.5
(2.89)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
6
(150)
10.0
(3.05)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
3
(75)
6
(150)
6
(150)
TABLE 1 - SC-160LP Bearing Capacity Table
(Assumes no spacing)
Minimum Required Foundation Depth in Inches (mm)
NOTE: The design engineer is solely responsible for assessing the bearing resistance (allowable bearing capacity) of the subgrade soils and determining
the depth of foundation stone. Subgrade bearing resistance should be assessed with consideration for the range of soil moisture conditions expected
under a stormwater system.
Содержание StormTech DC-780
Страница 2: ...An company TOOL 2 0 DESIGN ...
Страница 39: ......
