a)
Water Supply Interconnections
There shall be no physical connections between a public or
private potable water supply system and a sewer, or appurtenance thereto, which
would permit the passage of any sewage or polluted water into the potable
supply.
b) Location
Relative to Water Works Structures
1) Location
and Soil Condition
A) The engineering plan
documents shall show the location of all existing water works structures
(basins, wells, other treatment units, etc.) that are within 200 feet of the
proposed sewer.
B) Soil conditions
in the vicinity of the water works structures shall be investigated and
depicted on the plans.
2) Minimum Distances
The following minimum distances apply to clay and loan soils
and, as a minimum, shall be doubled for sand. In areas where creviced limestone
or gravel may be encountered, the Agency shall be contacted for a determination
as to what minimum separation distances and special construction will be
required.
A) Non-watertight sewers and
sewer appurtenances such as manholes and wetwells shall not be located closer
than 50 feet from water works structures.
B) Sewers located closer than 50 feet to
water works structures shall be constructed with water main quality pipe and
joints that comply with 35 Ill. Adm. Code
653.119.
All such pipe shall be pressure tested in accordance with "AWWA Standard for
Installation of Ductile-Iron Water Mains and their Appurtenances," ANSI/AWWA
C600-93 (1994), (no later editions or amendments) for a working pressure equal
to or greater than the maximum possible surcharge head to assure watertightness
prior to backfilling. No sewer shall be located closer than 10 feet from water
works structures.
c) Relation to Water Mains
1) Horizontal and Vertical Separation
A) Whenever possible, a sewer must be at
least ten feet horizontally from any existing or proposed water main.
B) Should local conditions exist which would
prevent a lateral separation of ten feet, a sewer may be closer than ten feet
to a water main provided that the water main invert is at least eighteen inches
above the crown of the sewer, and is either in a separate trench or in the same
trench on an undisturbed earth shelf located to one side of the
sewer.
C) If it is impossible to
obtain proper horizontal and vertical separation as described above, both the
water main and sewer must be constructed with water main quality pipe and
joints that comply with 35 Ill. Adm. Code
653.119
and shall be pressure tested in accordance with "AWWA Standard for Installation
of Ductile-Iron Water Mains and their Appurtenances," ANSI/AWWA C600-93 (1994)
(no later editions or amendments) for a working pressure equal to or greater
than the maximum possible surcharge head to assure watertightness before
backfilling.
2)
Water-Sewer Line Crossings
A) Whenever
possible, sewers crossing water mains shall be laid with the sewer below the
water main with the crown of the sewer a minimum of 18 inches below the invert
of the water main. The vertical separation shall be maintained on each side of
the crossing until the perpendicular distance from the water main to the sewer
is at least 10 feet. The crossing shall be arranged so that the sewer joints
will be equidistant and as far as possible from the water main joints. Adequate
support shall be provided for the water mains to prevent damage due to settling
of the sewer trench. Refer to Appendix H, Drawing No. 1.
B) Where a sewer crosses under a water main
and it is not possible to provide an 18-inch vertical separation, the following
special construction methods shall be specified (refer to Appendix H, Drawing
No. 2):
i) The sewer shall either be
constructed with water main pipe and joints that comply with 35 Ill. Adm. Code
653.119
and shall be pressure tested in accordance with "AWWA Standard for Installation
of Ductile-Iron Water Mains and their Appurtenances," ANSI/AWWA C600-93 (1994)
(no later editions or amendments) for a working pressure equal to or greater
than the maximum possible surcharge head or shall be encased in a carrier pipe
with the ends sealed, that, along with the joints, complies with 35 Ill. Adm.
Code
653.119.
ii) The water main
quality sewer or carrier pipe shall extend on each side of the crossing to a
point where the perpendicular distance from the water main to the sewer is at
least 10 feet.
iii) For the
required length of the water main quality sewer or carrier pipe, omit the
select granular cradle and granular backfill to one foot over the crown of the
sewer and use selected excavated material (Class IV) and compact to 95% of
Standard Proctor maximum density.
iv) Point loads between the sewer or sewer
casing and the water main are prohibited.
v) Adequate support shall be provided for the
water main to prevent damage due to settling of the sewer trench.
C) Where it is not possible for a
proposed sewer to cross under an existing water main, the specifications shall
require the construction methods set out in subsection (c)(2)(B) above and
shall require that any select granular backfill above the crown of the water
main be removed within the width of the proposed sewer trench and be replaced
with select excavated material (Class IV) compacted to 95% of Standard Proctor
maximum density. Where a proposed sewer must cross over a proposed water main,
an 18-inch vertical separation shall be maintained. Refer to Appendix H,
Drawing No. 3.
3) Sewer
Manhole Separation From Water Main
No water pipe shall pass through or come into contact with
any part of a sewer manhole.