HomeMy WebLinkAboutProposed Sewage System - GDC• LLOYD AND ASSOCIATES
ENGINEERS AND SIJF'VEYORS
REPORTS
DESIGNS
SUPERVISION
APPRAISALS
CONSULTATIONS
June 24, 1980
SFVi7AGF COLLECTION SYSTFM
ROBERT F. LLOYD
REGISTEREU C'VIL ENGINEER 353E
REG-STEREU LAND CURVEYOR 94.
6 3 5 2 O T H S T R E E T
VERO BEACH, FLORIDA
3296
SEBASTIAN HIGHLANDS - iTNIT SIXTEEN
The following report is the result of review of the Sebastian
Highlands, a portion of Unit 16, Phase One, Sewage Collection System
Plans as submitted to the City of Sebastian by General Development
Corporation as reviewed by Lloyd and Associates, Consulting Engi-
neers for the City of Sebastian, Florida.
The sewage collection system as proposed by General Develop-
ment is comprised of 8" P. V. C., SDR -35, Class 160, sanitary mains
at varying distances between manholes flowing by gravity to a wetwell/
lift station and pumped via a 10" P. V. C. force main. 1400 L. F. ± to
the proposed sewage treatment plant.
Although the minimum slope for 8" V. C. P. has traditionally
been established at . 476 or 4/10ths of a foot per hundred feet, P. V. C.
pipe has a reduced friction coefficient (. 11% vs. . 13%) and thereby
transmits greater quantities at reduced grades. It becomes extremely
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important to ensure that strict controls are adhered to with reduced
gradients to preclude increased maintenance costs for cleaning.
The selection of Flygt Pumps for the wetwell will reduce main-
tenance cost. "Flygt" has long been recognized as one of the leading
manufacturers of submersible pumps. The gravity system and appur-
tenances including the transmission system is good, except as follows:
1. Top elevations of manholes do not appear to conform
to paving and drainage plans. Following are random
manhold elevations:
Manhole
Number
Top of M. H.
Elevation
on G. D. C.
Sewer Plans
Top of M. H. Elevation
as scaled from
G. D. C. Paving
and Drainage Plan
7
23.20
23.69
12
24.50
24.67
15
23.00
23.27
17
25.70
25.95
29
23.70
23.10
2. An electronically detectable plastic tape should be buried
a minimum of 12" below ground surface of all sanitary
laterals.
3. Submit pipe manufacturers laying instructions to City
Engineer for approval prior to starting work.
4. Backfill for trenches on gravity and force main systems
to be compacted to 100010 density to a height l' above
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pipe and to 95'1'� density in 12" lifts to finished grade
for all r'w backfill outside pavement.
5. Backfill for trenches on gravity and force main systems
to be compacted to 100% density in 12" lifts for backfill
in pavement.. Density tests, as required by the City
Fngineer, shall be taken at the owners expense, except
that retests on failures will be charged to the Contractor.
6. All pipe to be laid in a dry trench. A wellpoint system
or other approved dewatering method shall be utilized
to maintain dry conditions.
7. Due to the depth of gravity system. 10. 631, and the wetwell
depth of 20. 87 feet, sheeting and shoring is the responsi-
bilitv of the Contractor.
8. Thrust blocking schedule for force main should be sub-
mitted for review.
9. Concrete encasement detail should be submitted for review.
10. Although a general concrete encasement notation is listed
on the cover sheet, specific locations are not indicated on
construction plans.
11. Rear lot line sewers are not recommended. Utility
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easements are not shown on plans. A fifteen foot easement
is the minimum practical width for rear lot maintenance.
12. Backfilling around manholes and other structures should
be accomplished in same manner as for connected pipe.
Fxtreme care should be used in backfilling wellpoint
holes to prevent settlement. The holes should be plugged
with a dry sand cement mixture (ratio 9 parts sand to 1
part concrete) to be placed immediately after pulling
well points.
13. Concrete for manholes should have a bearing strength of
3500 psi in 28 days and should receive a protective
coating on the interior and exterior surfaces with two
(2) coats of Hoppers Co. Bituniastic 300-M, PROCO FW -1
water base epoxy, as manufactured by Protective Coatings,
Tampa, Florida. or approved equal.
14. Manholes occurring in asphalt pavement should be
reset to grade after wearing course has been applied.
and a 40" x 40" x 8" concrete collar poured to wearing
course grade.
15. Mortar for jointing and plastering brick manholes should
consist of one part Portland cement and two parts of fine
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sand. Onlv the exterior surface of brick manholes should
be plastered with 3.%4 of an inch of cement mortar.
16. Precast concrete manholes should be constructed of
concrete attaining a minimum compressive strength
of 3500 psi in 28 days, using Type II acid resisting cement.
Construction shall conform to ASTM C478-70.
17. Infiltration and exfiltration leakage tests are required
of all sections of the system. including laterals. The
maximum allowable leakage as determined by 24 hour
infiltration,/exfiltration testing should be 50 gallons/day/inch
of diameter/mile. The test should be conducted to City
Engineer's requirements.
18. As noted on plans, shop drawings covering wetwell should
be submitted for approval to the City Engineer prior to
construction.
19. C. I. P. at wetwell and valve box should be of a working
pressure of 150 psi and conform with the requirements of
AWWA Standard C106 or C108 for cast iron.
20. Cast Iron Pipe and fittings for sewage transmission shall
be of enamel lined (not cement lined).
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":'
21. Fittings shall conform with the requirements of AWWA
Standard C110 for cast iron fittings. Flanged pipe and
fittings shall have barrels conforming with the require-
ments of AWWA C110, with integral cast or screwed on
companion flanges faced and drilled in accordance with
ANSI, 1121 .15-1975.
22. All hardware, bolts, anchors and accessories in the
wetwell and valve vault should be stainless steel.
23. Valve manufacturers shop drawings shall be submitted
to the City Engineer for approval.
24. Electrical components and installation should comply
with the rules of the National Electric Code. All
material should be new.
25. Ground rods should be copper clad steel not less than
3/4 inch in diameter 10 foot long. The maximum re-
sistance of each driven ground should not exceed 5 ohms.
26. All conduit should be P. V. C., minimum of 2" diameter
to each pump. Conduit should be sealed with zinc chromate
duct seal below the panel.
27. Prior to final approval of the station by the City and at
such times as the Engineer may direct, the Contractor/
Owner should conduct an operating test for approval. The
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equipment should be demonstrated to operate in
accordance with the applicable requirements in the
presence of the City Engineer or his authorized repre-
sentative. General Development Corporation should
furnish all instruments and personnel required for the
tests and the necessary electric power and water.
28. The Engineer or his designated representative should
perform ongoing inspection during the construction of
this system to ensure compliance with sound engineering
practices. Work should be stopped on any individual portion
or the entire project if, in the opinion of the City Engineer
the construction materials/methodologies are not consistent
with the best interests of the City of Sebastian or the future
residents of the proposed subdivision.
29. The Contractor/Owner shall maintain the site of the work
in a neat and workmanlike condition. The Contractor/Owner
shall remove all excess materials and all debris resulting
from all operations, and upon completion, leave the site of
the work in essentially the same condition as he found it. All
necessary steps should be taken to prevent objectionable blowing
or drifting of dust, sand or other debris.
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