EPA-bOO/2-75-072
December 1975
Environmental Protection Technology Series
ECONOMICAL RESIDENTIAL PRESSURE
SEWER SYSTEM WITH NO EFFLUENT
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development,
U.S. Environmental Protection Agency, have been grouped into
five series. These five broad categories were established to
facilitate further development and application of environmental
technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in
related fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to
develop and demonstrate instrumentation, equipment and methodology
to repair or prevent environmental degradation from point and non-
point sources of pollution. This work provides the new or improved
technology required for the control and treatment of pollution
sources to meet environmental quality standards.
This document is available to the public through the National
Technical Information Service, Springfield, Virginia 22161.
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EPA-600/2-75-072
December 1975
ECONOMICAL RESIDENTIAL PRESSURE SEWER SYSTEM
WITH NO EFFLUENT
by
Gerald F. Hendricks
Stephen M. Rees
SIECO, Inc.
Columbus, Indiana 47201
Grant No. S801041
Project Officer
James F. Kreissl
Wastewater Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Municipal Environmental
Research Laboratory, U.S. Environmental Protection Agency, and
approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of trade names
or commercial products constitute endorsement or recommendation
for use.
11
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FOREWORD
Man and his environment must be protected from the adverse effects of
pesticides, radiation, noise, and other forms of pollution, and the unwise
management of solid waste. Efforts to protect the environment require a
focus that recognizes the interplay between the components of our physical
environment—air, water, and land. The Municipal Environmental Research
Laboratory contributes to this multidisciplinary focus through programs
engaged in
• studies on the effects of environmental contaminants on the
biosphere, and
• a search for ways to prevent contamination and to recycle
valuable resources.
The technology described in this report represents one of the first
attempts to provide improved wastewater management for rural populations
in an economical manner while incorporating concepts of recycling valuable
nutrients to the land with concomitant elimination of additional pollutant
loads on surface water resources.
Louis W. Lefke
Acting Director
Municipal Environmental
Research Laboratory
111
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ABSTRACT
An economical pressure sewer system with no polluting effluent was
designed, constructed, and monitored for effectiveness. The elimination of
groundwater infiltration and restrictive elevation tolerances associated with
a conventional gravity sewer system enabled this type of sewer system to be
installed and to function economically. The treatment process, aerobic and
anaerobic lagoon storage with subsequent irrigation of the effluent, yielded
no more than normal volume of runoff.
Operational problems with the pressure system resulted from inefficient
home grinder-pump units. These problems were greatly reduced when commercial-
ly manufactured home units became available. The treatment process functioned
as anticipated. Because of the new sewer system, summer homes become year
around residences and new home construction exceeded expectations. As a
result, the initial irrigation area proved inadequate for handling the actual
flows and additional irrigation area was made available at a later date.
This report was submitted in fulfillment of Grant No. 801041 under the
sponsorship of the Environmental Protection Agency. Work was completed as
of December 1972.
IV
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CONTENTS
Abstract
List of Figures
List of Tables
Acknowledgements
Sections
I
II
III
IV
V
VI
VII
VIII
IX
X
XI
XII
XIII
XIV
XV
Conclusions
Recommendations
Introduction
Home Unit Production Problems
Home Unit Installation Problems
Grinder-Pump Unit Evaluations
Pressure Collection System
Vacuum Collection System
Storage and Treatment Lagoon
Lagoon Effluent Irrigation Data
Laboratory Analyses
Costs and Discussion
References
Publications
Glossary
Page
iv
vi
vii
viii
1
3
4
7
11
16
29
33
37
52
54
58
62
63
64
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FIGURES
No.
1 Grandview Lake Sewage Research and
Demonstration Project System Layout 5
2 Locally Manufactured Grinder-Pump Unit 8
3 Curb Valve and Riser Installation 14
4 Environment One-Unit 20
5 Hydr-o-matic Unit 22
6 Tulsa Unit 25
7 Overflow Absorption System Details 27
8 Automatic and Manual Air Release Valves 31
9 Vacuum Unit 35
10 Vacuum Pumping Station
70
11 Plan Layout of Treatment Plant °
12 Lagoon Levee Failure 46
13 Lagoon Levee Failure Cross Sections 47
14 Lagoon Levee Failure Cross Sections 47
15 Lagoon Levee Failure Cross Sections 48
16 Lagoon Levee Failure Cross Section 48
17 Lagoon Site Test Boring Logs 50
18 Revised Treatment Plant Layout 51
VI
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TABLES
No. Page
1 Summary of Maintenance Frequency 28
2 1972 Monthly Flow Data Summary 40
3 Daily Flow Data for July and August 1972 41
4 Daily Flow Data for September 1972 42
5 Daily Flow Data for October 1972 43
6 Daily Flow Data for November and December 1972 44
7 Analytical Summary 55
8 Analytical Data 57
9 Pressure Sewer Cost Breakdown 59
10 Approximate Home Unit Cost Comparison 60
VII
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ACKNOWLEDGEMENTS
The following individuals assisted in the completion of this project.
SIECO, Inc. - Consulting Engineers
Gerald F. Hendricks, Project Manager
Stephen M. Rees, Assistant Project Manager
Richard L. Sanson, Design Engineer
John F. McCaulay, Staff Engineer
Tony Hendricks, Laboratory Manager
Hershel B. Sedoris, Jr., Technical Aid
Charles Hollenback, Draftsman
David Sharp, Field Maintenance
Larry Smith, Field Maintenance
Lynn Higgins, Secretary
Farmers Home Administration (USDA)
Ralph Shelburn
Cecil Rose
James Jackson
Indiana State Department of Health
William Uhl
Steve Kim
Environmental Protection Agency
Charles Swanson
Jim Kreissl
Grandview Lot Owners' Association
John Wertz
George Noblitt
Robert Lindsay
William Luzius
Frank Hoffman
William Kendall
Mike Bova
Tom Gerken
John Sohn
Charles Shepard
Jack Riester
William Hooker viii
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SECTION I
CONCLUSIONS
1. It is possible to provide a sewage treatment facility meeting a zero-
discharge standard for small communities.
2. Domestic sewage nitrogen and phosphate can largely be converted to
vegetation at a reasonable cost for small communities.
3. Ground raw sewage and septic tank effluent can be treated by a combined
anaerobic and aerobic lagoon without objectionable odors.
4. Ground raw sewage caused some additional operation and maintenance
problems due to the nature of the solids.
5. Groundwater infiltration into sewer lines is eliminated with the use
of the pressure system.
6. A pressure sewage system can be cheaper to install than a conventional
gravity system in areas of rough topography.
7. Operational expenses of a pressure sewage system are higher than those
associated with a gravity system.
8. The home owner should be educated in the proper operation and mainte-
nance of his home unit.
9. No male-threaded PVC pipe fittings should be used on any home unit
installations.
10. Any check valves used in the home units should have a gate that, when
closed, is at an oblique angle from the perpendicular alignment of
the centerline of the flow in the pipe in order to use the gravitational
advantage. A free turning valve gate that reseats itself after each
operation proved to be more reliable and required less maintenance than
one with a fixed gate.
11. Mechanical seals should be used in all possible applications of infield
fabrication operations to prevent leakage due to high groundwater
conditions during all or part of the year.
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12. A fused electrical disconnect should be located next to any external
controls of the home unit for use by the serviceman. Any contractor
installing such a system for existing residences should have a flat
rate for each utility service damaged during installation.
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SECTION II
RECOMMENDATIONS
1. Future pressure sewer installations should strongly consider pumping
only septic tank effluent.
2. A program should be instituted to determine long-term maintenance
information on the effects of the ground paper products on pressure
sewer lines and treatment facilities. It is only through such infor-
mation that a proper cost comparison between grinder-pump installa-
tions and septic tank effluent pumping installations can be made.
3 The efficiency and dependability of any pressure switches installed
to prevent excessive pressures must be established before their
use is specified.
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SECTION III
INTRODUCTION
Grandview Lake, located about 10 miles southwest of Columbus, Indiana, is a
manmade lake with approximately 400 acres of water surface, and is shown in
Figure 1. (See glossary for metric conversions from English units used
throughout this text).
The lake is located in a rural section of Bartholomew County that is not pro-
ductive farm land. The soil in the area is predominately clay and, therefore,
provides poor drainage for crops. Scattered areas with exposed rock surfaces
further reduce the agricultural value of the land. These characteristics
that tend to keep land prices low also attract land developers. Such was the
case at Grandview Lake, and a recreational and residential development was
started.
As the Grandview Lake area developed during the last twenty years, the pollu-
tion problems inherently associated with a growing population began to become
evident to the residents. These problems were aggravated by the lake develop-
er's economic problems.
As the number of residences at Grandview Lake had grown, so had the size of
the lake. Financial difficulties had hampered the completion of the lake's
dam by the original developer. In fact, some lot owners had built septic
systems on the land between their dwellings and what they anticipated as
being the final lake shoreline. However, in 1960, additional funds were
invested in the development and the dam was completed. When the water began
to rise behind the completed dam, it began to cover some of the septic tank
absorption fields installed by the early residents. Some of these installa-
tions were abandoned for new facilities on higher ground. Some continued to
be used due to the ignorance of lot owners who had acquired property and
were anaware of where their septic system was located. Still others were used
out of indifference.
By 1967, residents of the lakeside community were becoming increasingly aware
of the results of septic tank effluent failing to be absorbed into the soil.
Not only were some septic systems emptying directly into the lake but the
flows from many of the newer septic tanks were causing odorous wet spots in
the lawns and eventually flowing into the lake. Algae growth was increasing
rapidly in the fertilized lake water, small coves around the lake had a
septic odor, beaches were becoming fouled, and some areas of the lake had soap
suds lining the shore. Also, a rural water system had been installed
(November 1969 thru May 1970) around the lake, and this was helping to attract
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LOCATION MAP
PVC PIPE (G1ZE AS SHOWN)
LAOOON CELLS
FIGURE 1. GRANDVIEW LAKE SEWAGE RESEARCH AND
DEMONSTRATION PROJECT SYSTEM LAYOUT
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more prospective homeowners and their sewage disposal problems.
The sewage problem could not be ignored if the lake was to continue to be a
desirable center of the community life.
Individuals had attempted to solve their own sewage problems by installing
various sewage disposal systems, but it was evident that a community system
was needed. Investigation into the feasibility of installing a conventional
gravity sewer system and treatment plant proved to be prohibitively expen-
sive ($10,000 per existing house), and this approach was abandoned.
The possibility of solving the sewage problem around the lake by installing
a pressure sewage system was first formally proposed by SIECO, Inc. in July
of 1968.
Although sewage force mains had been utilized by communities for many years,
the concept of individual pumping units located at each residence was defi-
nitely an experimental proposition. A prior attempt in Kentucky had proven
to be a failure . However, investigation into the Kentucky project failed
to reveal the true complexity of the proposed type of system. The engineer
anticipated that, by properly educating the population that would be using
the system, many of the problems on the Kentucky project could be avoided.
Also, the possibility of Federal research funds helped make the project
economically feasible.
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SECTION IV
HOME UNIT PRODUCTION PROBLEMS
Normal conditions expected when bidding a construction job did not material-
ize when the Grandview Lake project was advertised for bids. Most contractors
originally refused to bid on the project because it was something "new and
different." Those who did bid were unreasonably high. Eventually, a reason-
able bid for installing the system and treatment plant was received and
accepted by the owner. However, the heart of the pressure system, the indi-
vidual home units, was rejected by all bidders as "too complicated."
The engineer's original concept of the home unit to be used on the project
was a completely-fabricated three compartment steel tank, light enough to
be easily lifted into place by a backhoe. In an effort to keep installation
costs down, it was anticipated that the home unit fabricator would deliver
several units at a time to the job site. The contractor could then install
the units at his own pace without paying for a special piece of equipment for
lifting the unit into place.
However, when the fabrication of the home units was rejected by the bidder,
an alternate solution was sought to using a fabricated steel tank. The use of
a molded plastic or a fiber-reinforced plastic (FRP) tank was eliminated due
to the excessive mold or set-up cost associated with any initial production
using those materials. A local concrete vault manufacturer did express an
interest in casting the units out of concrete.
Being the only bidder willing to produce the unit housing at a reasonable
cost ($125.00/unit), the vault manufacturer was awarded the contract. He also
was awarded the assembly operation, subsequently awarded to a sub-contractor,
so that a totally "packaged" unit, as shown in Figure 2, would be delivered
to the site.
Production problems during casting forced the vault manufacturer to increase
the wall thickness of the unit. This added to the weight of the casting, but
did enable the casting mold to be removed without cracking the casting. It
also provided adequate room within interior partitions in the mold for the
concrete to be poured without having voids in the finished casting. The cast-
ing operation still required considerably more labor than originally anticipa-
ted by the manufacturer due to the required use of vibrators to help move the
concrete into the interior partitions.
Several months were spent eliminating problems with the mold. When actual
production began, the manufacturer could only produce five units per week.
It took five months to produce the 58 units for the project.
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f 14 1516 1011
12
13 5
/ ^1
9
oo
1. PRE-CAST CONCRETE UNIT U'x4'7"x4')
2. LID
3. SUMP
4. STORAGE COMPARTMENT FOR SOLIDS
5. STORAGE COMPARTMENT FOR LIQUIDS
6. DRY WELL
7. GRINDER
8. PUMP
9. CONTROLS PANEL
10. PROBE WIRES CONDUIT
I 1. CONTROLLER
12. CONTACTOR
13. DISCONNECT
14. GRAVITY INFLUENT LINE (FROM HOUSE)
15. DROP &ATE
16. ACCESS OPENING
17 ELECTRICAL SERVICE (FROM HOUSE)
18. CHECK VALVE
19. PUMP DISCHARGE LINE (TO MAIN)
20. PUMP SUCTION LINE
21. GATE VALVE
22. MANUAL CIRCUIT
23. AUTOMATIC CIRCUIT
24. GRINDER DISCHARGE
25 GRINDER INLET
FIGURE 2. LOCALLY MANUFACTURED GRIND-PUMP UNIT
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While the casting manufacturer was having his problems, the contractor doing
the assembly work was also experiencing problems. Problems resulted primarily
from attaching equipment, especially the garbage grinder, to the concrete
casting. The unit developed leaks between the wet well and the dry well.
These problems were eliminated by having threaded anchor plates cast into
the concrete. A quick-setting hydraulic cement was used to secure all pipes
where they passed through the walls of the casting.
A considerable amount of time was lost due to logistic problems in obtaining
parts. Plastic pipe had been specified by the engineer because of its low
cost, corrosion-resistance and ease of installation. The contractor found
that local material supply houses did not carry the specified thickness of
plastic pipe and had problems getting both the pipe and the required fittings.
After each unit was completed, the fabricator tested it under the engineer's
supervision. In these tests a problem was discovered during the grinding
cycle of the operation. The garbage grinder was using twice the amperage
indicated by the manufacturer. Correspondence with the manufacturer failed
to produce a satisfactory explanation. By closely monitoring the water level
above the grinder's cutting blades and the amperage being used, it was
discovered that a liquid head over 8.25 inches above the cutting blades
resulted in the excessive amperage. The unit was actually pumping the liquid
in addition to grinding.
The normal operation of a garbage grinder consists of water and garbage being
poured into the grinding chamber without building up a significant head.
This accounted for the manufacturer being unaware of the situation. When
conditions are such in a household garbage grinder installation, the duration
of excessive power drain is usually short enough that the thermal overload
on the grinder is not activated. Any such overloading that results in the
thermal overload stopping the grinder would probably be blamed on "something
stuck in the grinder."
The problem, overloading due to the height of the liquid level above the
grinder, was solved by adjusting the liquid level controls in the unit so that
the head did not exceed 8.25 inches above the cutter blades. However, this
meant the storage capacity in the unit was reduced, thus requiring more
operating cycles during the usage period.
In the event of a pump malfunction, it was possible for the electrical liquid-
level control conduit to become submerged. It was therefore necessary to seal
the wires inside of the conduit. Waterproof putty, aquarium sealer, and a
petroleum base mastic cement proved ineffective in stopping the water. Even-
tually, a quick-setting hydraulic cement was used to solve the problem.
Piping within the units was done with Class SDR 21 PVC pipe. An immediate
discovery was that no male-threaded PVC fittings could be used regardless of
the wall thickness (Class 120 is the minimum acceptable by the engineer in
other instances). Metal nipples screwed into threaded female PVC fittings
with a solvent-weld female connection to the piping was the only type of
threaded connection that did not break under stress during the operation of
the pumps.
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In one instance, a section of pipe connected to the discharge of a positive-
displacement pump withstood an estimated pressure of 105 psi and the con-
comitant increase in temperature due to a closed gate valve. Although the
pipe expanded to almost twice its original diameter, neither the fitting,
pipe, nor weld broke. The pump failed, however.
Schedule 40 PVC pipe was used in the units after it was discovered that
maintenance personnel and curious home owners used the pipes to stand on when
climbing in and out of the unit.
10
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SECTION V
HOME UNIT INSTALLATION PROBLEMS
Increasing the thickness of the walls and partitions strengthened the unit,
enabled mounting brackets to be cast in the wall, and made the unit too heavy
to be picked up with a backhoe. The contractor installing the units then
arranged for the vault manufacturer to set the units into place with his boom
truck. This tended to limit the flexibility of the home owner, engineer, and
contractor in selecting the unit location. Alternate solutions considered
included using a large boom crane to lift the units over the houses from the
county road; flying the units into the lots with a large helicopter from
Louisville, Kentucky; using a barge equipped with a crane and placing the
units from the lake; and using a crawler-type front end loader. The first
three alternates were eliminated due to the weight of the unit, cost, and
increased contractor liabilit} The last was eliminated by the county commis-
sioners refusing to let any crawler equipped equipment onto the shoulder or
surface of the county road.
Faced with having to reduce the weight of the unit, the contractor decided to
set the top on the unit in the field. Mortar, concrete, hydraulic cement,
tar, and epoxy cement were all used and proved unsatisfactory for field
installations. The problem was solved by using RAM-NEC, a bituminous gasket
material (manufactured by K. T. Snyder Company, Houston, Texas). In fact,
a unit could be shifted by lifting rings in the top once the top was sealed
with the RAM-NEC. A problem arose because of this virtue—if the interior
partitions of the unit were not covered completely at their connecting point
with the top, then voids would be left between the wet and dry sides of the
unit. The top could not be removed so the crack had to be cleaned and then
sealed with epoxy cement. This greatly increased the labor cost of installing
the unit.
It is recommended that any field work involved creating a waterproof seal be
eliminated if at all possible. If not, then a mechanical seal is recommended.
The home grinder-pump units were installed and connected to the piping between
the house and the septic tank of the existing houses around the lake. Many
of the houses and their septic systems had been constructed prior to the
additional extra fill placed over the septic tank. This meant that many of
the grinder-pump units had to be installed from 5 to 9 feet below the existing
ground surface.
The access into the compartments in the unit was then through a concrete pipe
placed over the openings. The concrete pipe proved to be just as difficult
11
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to seal as was the unit itself. RAM-NEC proved to be the only product that
was reasonably reliable in assuring a watertight seal.
Due to the limited flexibility in the adjustment to grade of the height of the
riser pipe over the compartment openings, the unit fabricator cast some 6-inch
tall pipe extensions for use in height adjustments of 6 to 18 inches. These
proved to be a good idea in the office, but a failure in the field. The rings
were 4 inches thick to prevent breakage during the field installation. When
installed, these rings were never sealed completely. While not having any
openings directly into the unit's compartments, a space was left between the
sealant and the outer edge of the riser ring. Water would collect in this
void and, upon freezing and thawing, break the seal between the rings. The
only prevention was to apply a sand-mix coating around the outside of the
joint. This proved to be expensive in both labor and time lost in completing
the installation.
The problems involved with leakage, broken service lines, vandalism, and
exposure to liability can be directly related to the amount of time that elap-
ses between the digging of the hole for the home unit and the backfilling of
such. Units left overnight without being backfilled proved, time after time,
to cost the contractor lost time and money the next day. Eventually, the
contractor refused to start installing a unit unless he could finish it
(excluding the electrical installation) on the same day.
The electrical connection of the unit was contracted independently by each
home owner. This was done due to the uncertainty of predicting the cost of
such installations. The location of the electrical controls was left to the
discretion of the home owner, and, therefore, no uniform location resulted.
Locations chosen ranged from outside the house under the roof overhang to
inside a linen closet in the master bedroom. The best location, from the
service man's standpoint, proved to be the garage. Two notable exceptions to
this were when the location chosen in the garage was above the family's food
freezer and when the home owner had a habit of locking the family's canine
member in the garage without warning the service man.
In summary, the location should be such that access to the controls is avail-
able without entering the home and without having to climb over articles stored
in front of the controls. NOTE: A fused electrical disconnect should be
located next to the controls for use by the service man.
It was originally anticipated by the engineer that the majority of the existing
utilities at each home could be located, to some degree, by the home owner.
This would have enabled the contractor to avoid cutting most of those services
by locating the pressure sewer service line elsewhere. Nothing could have been
further from the truth. With very few exceptions, the home owner's information
proved to be of no value to the contractor.
One home owner, absolutely positive of the location of all of his utilities,
located the path for the trencher to follow. Consequently, the contractor
followed that route and cut the water line, the telephone line, the electrical
line to the man's boat house, the electrical line to a light by his driveway,
and his gas line three times. This was the record for services cut. The
12
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average number of services cut per house was 1.3.
It is suggested that any contractor installing such a system be given a flat
amount for each service repair required when the service line is installed
according to the home owner's instructions.
A curb cock valve (See Figure 3) was installed in all of the service lines
between the system main and the home unit. PVC valves produced by Water and
Gas Products of Tulsa, Oklahoma, were used in these installations. These
valves developed leaks around a metal ring used to hold the gate in the body
of the valve. When informed of this problem, the manufacturer modified his
valve and solved the problem.
An extension of 4-inch pipe was placed over each valve to enable a valve key
to be used to open and close the valve without having to dig it up. The
extension was then capped to prevent the dirt and water from collecting over
the valve. Two types of caps were used:
1. A solvent-weld one-piece cap pressed over the end of the
pipe without solvent
2. A threaded plastic sewer clean out
The second solution proved to be the best because the cap remained functional,
even when people stepped on it. The first type would become wedged on the
pipe under similar circumstances and was difficult to remove.
Several service lines were broken when cars ran over the extension above the
curb cock valve. A solution to this problem would be a collapsible valve
extension, as shown in Figure 3.
Several types of service line material were used on the project. The following
is a summary of the various materials used and an evalution of each:
Type
PVC-SDR 21
(20-ft. lengths)
PVC-SDR 13.5
(20-ft lengths)
PVC-SDR 21
(20-ft lengths)
Polypropylene
(roll)
Polybutylene
(roll)
Nominal
Size(inch)
1.5
Flexibility
Limited
Limited
Limited
Good
Good
Type of
Fittings
Solvent Weld
Coupling
Solvent Weld
Coupling
Solvent Weld
Coupling
Cold-Flared
w/brass
Cold-Flared
w/brass
13
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PVC THREADED SEWER CLEAN-OUT
SOLVENT WELD
•—4" PVC PIPE CLASS SDR2I I.D. 4.072"
/'PVC PIPE CLASS SDR 26 O.D. 4.000'
TO HOME UNIT
CURB VALVE
I "SERVICE LINE
J
BRICKS / STONES/CONCRETE PAD
TAPPING SADDLE
•W/ CURB VALVE FOR
PRESSURE TAP
FIGURE 3. CURB VALVE AND RISER INSTALLATION
14
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PVC-SDR 21 - This was the easiest pipe to obtain because it is a
standard stock item of most local plumbing supply firms. There were
several instances where service lines of this material broke due
to settling of the home unit. We would not encourage its use.
PVC-SDR 13.5 - This is not a standard item stocked by
most local plumbing supply firms. However, the 0.097-inch
wall thickness compared to the SDR-21 pipe (0.063-inch) is
worth the difference in price (approximately 5^/foot).
There were no breaks or leaks in any service lines due to
unit settling, stone bruises, etc., when this pipe was installed.
This was the best service line material used in the opinion of
the service men.
PVC-SDR 21 (1.5 inch) - Satisfactory performance.
Polypropylene - This pipe with cold-flared brass fittings was
relatively easy to work with, but care had to be taken not to
bend the pipe excessively. The pipe would not break, as would
the PVC pipe, but it would develop a kink which would restrict
flow and eventually rupture under pressure. Although it costs
more than the PVC, no time is wasted waiting for a solvent to
set up. This is a good service line material if the installation
is proper.
Polybutylene - Same conclusions as for polypropylene
15
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SECTION VI
GRINDER-PUMP UNIT EVALUATIONS
The Original Unit
The locally fabricated home grinder-pump unit did not prove to be effective
in grinding and pumping the domestic waste for the following reasons:
1. Leakage between the wetwell and drywell
2. Electrical control failures
3. The placement of the grinder
4. When the pressure in the main line exceeded the
maximum head of the centrifugal pumps then the
pumps overheated causing leaks in the plastic
piping in the units
The largest single factor in the failure of the locally manufactured grinder-
pump unit was due to leakage problems. Both external and internal leakage
into the drywell caused repeated electrical failures. Although various
methods were used to solve the leakage problem, the pre-cast concrete container
was both too heavy and too difficult to make water tight to be considered
in future installations.
Electrical control failures were the second most frequent cause of unit
malfunctions. Several problems with the electrical equipment resulted from the
electrical panel being located in the unit. The panel was located there to
enable servicing of the electrical equipment with maximum efficiency by
allowing easy observation of equipment performance relative to electrical
adjustments. However, in any installation of electrical equipment in a dry-
well below grade, provisions for humidity control should be considered regard-
less of size. Funds available did not permit this on the Grandview project
and therefore the electrical panel had to be removed from the drywell. This
resulted in additional service time during maintenance.
It had been assumed that a relatively dry compartment would be available
within which to mount the panel. Watertight enclosures for the electrical
equipment were utilized, but condensation within the equipment enclosures
caused contactor malfunctions. A small light bulb was installed in the
contactor housing, and this alleviated the moisture problem in the contactor.
It was anticipated that all of the equipment within the unit would be provided
with fused protection. While being sound in theory, the idea proved to be un-
workable in the field application. A single fused disconnect proved to be the
best arrangement for providing electrical overload protection.
16
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The electrical contactor was sized based upon the manufacturer's recommenda-
tion relative to the anticipated amperage used during the operation of the
pump and grinder. As discussed previously, the garbage grinder used twice
the amperage expected by the manufacturer when the liquid head exceeded
8.25 inches above the cutting blades. This caused the total amperage to
exceed the rated capacity of the contactor. This in turn, caused the con-
tactor to fail. Additionally, the frequency of grinder and pump operation
was increased when the storage above the grinder was reduced. The sturdier
construction of the next larger size contactor proved to be well worth the
additional cost. This was an instance when deliberate over-design by the
engineer would have been beneficial in the operation and durability of the
product.
Several of the contactors that failed structurally were returned to the
supplier and forwarded to the manufacturer. It was interesting to note that
the following year's model of contactor had been strengthened at the points
of failure observed by the maintenance crew.
Electrical probes and float switches were used in the unit and both proved
to be relatively trouble-free. The effectiveness of the probes was somewhat
less than that of the float switches. This could be attributed to the solids
accumulating on the probe surface. While solids accumulated on the float
switches, it was not a problem. The probes initially were submerged and after
the unit had been emptied were not in contact with any liquid. This enabled
the solids to dry and form a crust which was relatively resistant to elec-
trical conductivity. The float switch used to shut off some units remained
in contact with the liquid so that the solids did not dry and accumulation
was minimal. It is suggested that a pressure switch or float switch is
superior to a probe control for use in a home unit.
In summary, the electrical design of any home grinder-pump unit should be as
simple as possible and capable of operating under the worst possible conditions.
Design sizing should include at least a 50% safety factor in estimating anti-
cipated amperage loads.
The locally produced grinder-pump unit was designed to store the raw waste
from the home until 120 gallons (later reduced to 80 gallons due to problems
associated with maintaining a liquid head above the grinder) had been collected.
At that time, the grinder and pump started simultaneously.
The problem with this system was that every solid object that was put in the
home drainage fixtures had to eventually pass through the grinder. Regardless
of the degree of customer education in the proper use of the grinder-pump unit,
objects got into the unit that could not be ground. This caused the grinder
to jam and either blow a fuse or activate the thermal overload protection
protector. This meant that the home unit would then overflow into the standby
leaching bed until the unit was repaired.
It is not realistic to provide for grinding the total solids accumulation from
the home; therefore, some provision for removing heavy objects prior to the
grinding step should be provided. It is interesting to note that the Environ-
ment/One, Hydr-o-matic, and the Tulsa units all use the suction lift of their
17
-------
pumps to pass the sewage through their grinders, i.e., the grinder is suspen-
ded above the bottom of the sump. This enables a heavy object such as a nail
to remain on the bottom of the sump and avoid entering the grinder. This is
a definite asset for all three units.
Leaks developed in the piping of several of the locally manufactured units
rather consistently. It was discovered that this was caused indirectly by
the pressure in the main line of the collection system. When the pressure
exceeded 35 psi, the non-flushing centrifugal pumps (shutoff head of 35 psi)
would continue to run without pumping any liquid. When this condition per-
sisted for a significant period of time, a considerable amount of heat was
generated and caused the plastic pipe to be weakened where it was connected
to the pump. The point of leakage was always in the threaded connection which
joined the metal and plastic pipes. This problem was eliminated by the
maintenance of a low pressure in the main line.
While the overall performance of the locally manufactured grinder-pump units
was unsatisfactory, it is interesting to note that one unit worked successfully
for 10 months prior to replacement with no malfunction. However, the physical
dimensions of the unit (4 ft. x 4 ft. x 4.5 ft.), its weight and the grinder
location were not suitable for general application.
Flushing Units
The original system was designed with two flushing units on each main line.
Each of these units consisted of a 1,000-gallon storage tank connected to a
pumping unit that was activated every 24 hours by a timer. The two units'
timers on each line were synchronized to allow simultaneous pumping. A mini-
mum flushing velocity of 3.01 feet per second was anticipated in the 3-inch
main lines.
The pump used was a Flint and Walling (Model 101) two-stage centrifugal pump
which operated very well. While the pump was started by a timer, it was turned
off by a float valve. Some difficulties in adjustment were experienced with
the timers utilized on the unit. Power interruptions caused difficulties
with the timers by altering the operating period of the units. A backup system
of power for the timer, such as a wound spring, would have been beneficial.
This feature was used when a replacement timer was required.
The flushing units were the most successful of the locally manufactured units.
These units were designed with higher available heads than other units which
permitted their operation during periods of restricted flow, due to air locks
in the main line. However, they pumped when the normal system flow was lowest
and subsequently the line pressure was low.
The problems discussed earlier which plagued the locally manufactured units
were also found to a lesser degree on these units. Water leakage into the
unit was reduced because RAM-NEK sealant was used, and piping leaks were re-
duced because Schedule 80 PVC pipe was used.
Actual flushing flows did not meet the Engineer's expectations. The anticipa-
ted daily flows from the homes having flushing units were not as great as
18
-------
expected. One resident having a flushing unit did not occupy his home during
much of the winter, despite a past history of occupancy during this season.
A better solution would have been for the flow from several homes to have
been collected in a common storage tank for flushing liquid.
A total system of units utilizing the large storage capability and the time-
controlled pump offers countless possibilities of regulating flow rates within
a system. An extension to the original system was installed, and the Engineer
recommended such units be installed at each house connected to the extended
line. Their flow was to be stored and pumped at night when other flows were
reduced.
The Environment/One Unit
The Environment/One Unit was marketed in a way that was very attractive to
the lot owners' at Grandview Lake. The manufacturer offered to furnish and
install the residential pumping units. Later, a service agreement was
offered by the manufacturer through its contractor-representative. This
idea of a total package program available to the owner, where no operating
utility maintenance program existed, was superior to contracting each unit
individually. The convenience of dealing with one supplier-installer-service-
man far outweighed any potential cost savings to be realized through separate
contract negotiation by each o.mer. An Environment/One Unit, as installed,
is shown in Figure 4.
The E-l Unit, Model 210, is a 1 horsepower motor-driven progressing-cavity
pump with a cutting blade attached to the suction end of the pump's rotor.
The progressive cavity pump is manufactured by the Moyno Pump Division of the
Robbins and Myers Company, located in Springfield, Ohio. Similar pumps were
used in the 20 locally manufactured units and proved to be very reliable.
The Moyno pump is designed so that the metal pump rotor turns within a rubber
stator creating a progressive compression action. Although there is some
safety factor available due to slippage between the rotor and the stator
during periods of restricted pump discharge, for all practical purposes, the
pump should be considered a positive displacement type.
If during the operation of progressing cavity pumps an abrasive particle can
become imbedded in the stator and score the rotor, this may eventually lead
to failure of the stator itself. The E-l Unit was equipped with a modified
stator designed to reduce failures due to abrasive scoring. However, by
increasing the durability of the stator, the amount of slippage between the
stator and the standard size rotor is reduced. This intensifies the positive
displacement characteristic of the pump and results in the need for a thermal
overload switch as an integral part of the unit.
In several instances where the pump discharge was restricted completely, the
rotor failed. The point of failure appeared to be within the area of contact
between the rotor and the stator. Abrasive particles scored the surface
of the rotor in every instance observed. The abrasive action of the foreign
19
-------
HEIGHT VARIES
AS NEEDED
PRESSURE SENSING TUBE
24" DIAMETER
CONCRETE PIPE W/LID
liT^f-^
smsSir GROUND LEVEL
BREATHER
aOVERFLOW
INDICATOR
(IN HOUSE)
GATE VALVE
UNION
WATERPROOF SEALANT
4" OVERFLOW
(OPTIONAL)
NDTOR
1 1/4" DISCHARGE LINE
CHECK VALVE
PUMP - PROGRESSIVE
CAVITY TYPE
FIBERGLASS TANK
GRINDER
FIGURE 4. ENVIRONMENT/ ONE UNIT (Courtesy
of Environment/ One)
20
-------
particle was evidently intensified by expansion of the stator due to increa5;
temperature.
The unit uses a thermal overload on the pump motor to limit the exposure to
high operating temperatures. However, experience did not indicate that the
thermal overload reacted quickly enough in all instances to prevent damage
to the stator. There were several instances where unit failure was attributed
to prolonged continual pump operation resulting in the main bearing seizing
and locking up the pump. In these instances, the overload switch failed to
operate in time to prevent damage to the unit.
During the project, an anti-siphon feature was added to the unit by the
manufacturer. This eliminated the maintenance required due to air-locking
that was experienced on the original Environment/One Units.
The unit housing is light weight fiberglas tank with a steel plate on top.
One person could easily install one of these tanks on the construction site.
However, the grinder-pump itself weighs 140 pounds. The units were normally
installed 30 to 36 inches below grade, and this, coupled with the pump weight,
necessitated more than one person to install or remove the pump for maintenance
purposes. An alternative would have been to provide a single maintenance man
with a mechanical lifting device to remove the unit.
The unit is designed for installation in the basement of the house served.
Customer preference, lack of suitable space in existing homes, and access
needed for maintenance purposes resulted in outdoor installation of most of the
units. Access to the unit below grade was made by placing a pre-cast concrete
tile over the unit and sealing it to the unit with a petroleum base sealer.
Mechanical equipment was needed to lift the concerte tile into place and the
sealant was applied carefully to prevent water leaks into the unit.
Each unit is equipped with a warning light that may be located in the house.
This light indicates unit malfunction and is provided as a convenience for
the home owner.
The unit electrical controls were located near or in the home electrical panel.
The Hydr-o-Matic Unit
The Hydr-o-matic units utilized at Grandview Lake were used under two situa-
tions - grinding and pumping raw sewage, and pumping septic tank effluent.
The grinder-pump units were less successful than those pumping only septic
tank effluent, but both types of installation required maintenance. The
unit was very rugged, but had operational problems. Figure 5 is a schematic
diagram of the major elements of a Hydro-o-matic grinder-pump installation.
The basic grinder-pump unit was a 1.5 horsepower submersible centrifugal pump
with grinder blades preceding the pump. The tank housing was made of steel
and the unit piping was galvanized. The grinder-pump discharge piping was
connected to the plastic service line by a hydraulically sealed discharge
flange. Backflow from the system main during pump removal was prevented by
a gate valve, located within the tank, whose valve stem was extended to
21
-------
CONTROL
BOX
TROUBLE LIGHT
RESET
TO POWER CORD
TO CONTROL CORD
POWER SOURCE
RUN LIGHT
/ (WHITE)
-HAND-OFF-
AUTO SWITCH
TO JUNCTION
WATERPROOF
CABLE
SPLICE
SEAL-TITE PROTECTORS WITH
QUICK-DISCONNECT PLUG AND
RECEPTACLE
LIFTING CHAIN
1/4" THICK STEEL TANK
3/4" GALVANIZED
GUIDE RAILS
GATE VALVE
DISCHARGE PIPE
HYDRAULICALLY SEALED
DISCHARGE FLANGE
BALL CHECK VALVE
4" OVERFLOW (OPTIONAL)
SEALED MERCURY FLOAT SWITCH
GRINDER-PUMP
FIGURE 5. HYDR-0-MATIC UNIT (Courtesy of
Hydr-0-Matic)
22
-------
within inches of the top of the unit housing. The positioning of the grinder-
pump in the unit was controlled by guide rails on opposite sides. A sealed
mercury float switch was used to control the grinder-pump operation. Back-
flow into the unit from the system main was prevented between normal operating
cycles by a ball check valve between the grinder-pump and the hydraulically
sealed discharge flange.
After the gate valve was closed, the grinder-pump was removed by pulling on a
chain attached to it. Although the guide rails aided in removing and install-
ing the grinder-pump, removal by a single maintenance man was still difficult
due to the weight of the grinder-pump and attached piping (approximately 85
pounds).
The location of the unit's check valve created the biggest problem with the
unit. During periods of excessive main line pressure, the hydraulically
sealed discharge flange leaked badly. This caused the unit to operate continu-
ously. If the check valve had been located between the discharge flange and
the gate valve, this could have been prevented. Several instances of check
valve failure and leakage due to fouling with solids and stringy matter also
occurred. The ball check valve was not as satisfactory as the swing check
type.
One pump had a problem with air locking. This caused continual operation with
no liquid movement and subsequent overheating and pump failure. The pumps
were not equipped with an anti-siphon device. This was prevented in the
problem unit by drilling a 0.125-inch hole in the discharge pipe between the
pump and the ball check valve.
The pump control, a sealed mercury float switch, proved to require a lot of
maintenance. The construction of the float was faulty in that it leaked.
The manufacturer has since corrected this problem. Since the float was
installed to operate between the grinder-pump and the tank wall, one unit,
installed in smaller (20-inch) diameter tanks, malfunctioned due to a build-up
of grease and solids on the tank wall. This crust built up until it prevented
operation of the float switch. The manufacturer's representative suggested
that the home owner hose down the inside of this unit periodically to prevent
such a build-up.
Installation of the unit was restricted because there was no provision for
extending the height of the unit housing beyond that specified prior to
fabrication. This was a major problem to the contractor installing the unit.
Care should be taken in specifying the tank dimensions and type to allow for
depth variations upon installation.
The unit controls,, excluding the mercury float switch, were housed outside
the unit, usually in the customer's house. A red trouble light came on
during periods of pump malfunction and a white one during normal operation.
A reset button was provided for use when the unit had stopped due to a
temporary condition such as overheating of the pump motor. When the reset
button would not start the pump, the maintenance people were notified.
23
-------
The Tulsa Unit
The Tulsa unit was a lightweight submersible grinder-pump housed in an FRP
tank with an adjustable access riser. Plastic products were used whenever
possible in the unit.
The grinder-pump consisted of a 1 horsepower motor, housed in a stainless
steel outer casing, with a grinder-pump attached. An installed Tulsa unit
is shown in Figure 6.
The motor proved to be dependable but slightly undersized. The grinder-pump
was not dependable. The grinder blades were held in place on the shaft by a
metal key. The pump's vibrations during operation caused the key to fall out
and the shaft to spin without turning the blades. Subsequently, the manu-
facturer welded the blades to the shaft, but this made replacement very
difficult.
The stainless steel outer casing acted as the unit's on-off switch. An ad-
justment for regulating the duration of operation of the pump was located in
the handle on top of the motor. Vibrations during operation loosened the ad-
justment screw. This caused the grinder pump to run continuously or not at
all.
The unit's centrifugal pump was rated at 12 gallons per minute at 35 psi.
Actual experience indicated that performance was considerably below the
rating.
The Tulsa unit provided the largest total storage capacity of all the com-
mercial units (71 gallons). A concrete anti-flotation collar was also re-
quired for this unit, as shown in Figure 6.
PVC piping was used in the unit. A PVC "quick-connector" compression-type
fitting was used to connect the discharge piping from the grinder-pump to the
service line. A PVC corporation valve was used to prevent backflow from the
system main line into the unit when the compression fitting was removed. A
bronze check valve was used.
Initial problems were experienced with the discharge piping due to the lo-
cation of the check valve. Originally, the check valve was located in the
vertical discharge line close to the grinder-pump. This created two problems.
First, the grinder-pump had to be removed to service the check valve.
Second, the ground solids, particularly paper, collected on top of the valve
gate, preventing it from seating properly. While the first problem was an
inconvenience to the maintenance men, the second meant that backflow from the
system forced the unit to cycle continually.
The check valve problems were nearly eliminated when the check valve was
moved to a short horizontal section of piping (See Figure 6) accessible to
the maintenance man without removing the grinder-pump.
24
-------
GROUND
LEVEL "
LOCK
CHECK
VALVE
48"
1"
PVC
CORPORATION
COCK
PVC
DISCHARGE
LINE
30"
I
CHAIN FOR
LIFTING
GRINDER-PUMP
J /
MACERATING
BLADES
ADDITIONAL RISER
EXTENSION AS NEEDED
POWER SOURCE -
SYSTEM MONITOR &
CIRCUIT BREAKER
LOCATED IN THE HOME
DISCONNECT
PVC COMPRESSION
COUPLING
CONCRETE
ANTI-FLOTATION
COLLAR
FIBERGLASS TANK
OVER-FLOW
ELECTRICAL CORD
PUMP HANDLE AND
CONTROL ADJUSTMENT
SCREW
SUBMERSIBLE MOTOR
W/STAINLESS STEEL
OUTER HOUSING
SUBMERSIBLE PUMP
FIGURE 6. TULSA UNIT
25
-------
The Tulsa unit did incorporate some very good features. The grinder-pump was
light enough for one person to remove easily. The fiberglas tank was easy to
install. The access riser was easily adjustable to different heights during
construction. Also, when the grinder-pump operated, it did not incur a build-
up of grease and solids around the sides of the tank as did the other units.
The unit was also equipped with a remote warning light and reset button.
Additional research and development is needed to bring the unit's reliability
into an accepted range for an operating utility. Subsequent correspondence
with the manufacturer indicates that such research is being initiated in a
project at Wichita Falls, Texas. Results of this work are scheduled to be-
come available in the near future.
Miscellaneous
An overflow adsorption system was recommended by the Engineer (See Figure
7) for all of the home units. However, considerable infiltration into these
systems with overflowing into home units caused increased unit operation and
increased flow at the treatment plant.
A summary of maintenance frequency by cause and type of unit is shown in
Table 1.
26
-------
13'»B MO'
NJ
ERVICE LINE
SEPTIC TANK
ROAD
FORCE MAIN
-ABSORPTION BED
Typical Profile of a New Residence Installation
PRE-CAST CONCRETE PIPE
OVERFLOW LEVEL
-EARTH FILL
POLYETHYLENE
F:LM
PERFORATED
PVC PIPE
SEPTIC
HOME PUMPING UNIT-O'™
x 'Absorption Pit Detail X-Section
JDR - (7° SLOPE UP)
PEA GRAVEL
ABSORPTION
BED
Plan View
NOTE: SEPTIC TANKS ARE NOT INSTALLED WITH HOME UNITS THAT GRIND
AND PUMP RAW SEWAGE
FIGURE 7. OVERFLOW ABSORPTION SYSTEM DETAILS
DESIGN CONSIDERATIONS
1 . THE ABSORPTION PIT SHOULD
BE AT LEAST 31 x 4'
2. PEA GRAVEL SHOULD BE USED
IN THE ABSORPTION BED
3. THE ABSORPTION BED SHOULD
HAVE A MINIMUM VOLUME OF
500 CUBIC FEET
4. THE LOWER ELEVATION OF
THE ABSORPTION BED MUST
BE ABOVE THE LAKE OR
OTHER PONDED WATER
5. THE ABSORPTION BED CAN
NOT BE LOCATED WITHIN
OF ANY WELL
6. STANDARD RECOMMENDATIONS
OF THE STATE BOARD OF
HEALTH ON SEEPAGE PITS
MUST BE OBSERVED
-------
Table 1. SUMMARY OF MAINTENANCE FREQUENCY
(2-year period)
Locally
Manufactured
Cause Unit
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Pump Failure
Grinder Failure
Piping Failure (within tank)
Electrical Failure
(excluding controls)
Control Failure
Piping Failure (outside tank)
Infiltration/inflow of water
Collection System Malfunction
Improper Installation
Miscellaneous
Totals
Maximum Number of Units
52
25
41
66
23
11
56
7
9
81
371
27
E-l
Unita
4
0
4
3
0
2
1
1
2
0
17
15
Hydr-o
-matic
Unita
8
1
7
2
10
8
0
2
2
12
52
28
Tulsa
Unit
2
2
1
0
2
0
0
4
0
5
16
2
Maintenance of the E-l units was done primarily by the manufacturer's repre-
sentative. The hydr-o-matic units were serviced by the manufacturer's field
personnel as malfunctions were reported to the factory. Therefore, the
figures listed above were based on the field notes taken by the engineer's
maintenance crew and may not include all of the service calls by others.
28
-------
SECTION VII
PRESSURE COLLECTION SYSTEM
The sewage collection system at Grandview Lake consisted of 28,312 feet of
3- and 3.5-inch PVC pipe installed 36 to 42 inches below the ground surface.
One main line on each side of the lake was installed to serve approximately
one half of the total inhabited shoreline. The two lines both discharged
into a 5-inch line which terminated at the treatment plant.
Pressure from the individual home units was sufficient to pump liquid and
ground solids to the treatment plant without the use of mainline pumping
stations. There were several problems associated with the collection system,
but the practicality of the design concept of such a collection system was
demonstrated sufficiently to encourage similar future projects.
It was the original contention of the engineer that main line check valves
were not needed because the system would be under continual pressure and such
valves would be an added installation and maintenance expense to the utility.
For economy of installation additional gate valves were not installed at
regular intervals on each line.
While the use of main line check valves should be minimized, their use
at intersections of large mains (10-inches in diameter or larger) and at
specific points of potential hydraulic problems should be considered during
design. Gate valves should be provided on lateral main lines and at inter-
vals sufficient to isolate twenty to thirty individual customers for any
maintenance required.
Service line connections to the main line while the system was in operation
necessitated several maintenance calls. There were leaks due to improper use
of the tapping tool. However, once having experienced the results of an
improper service tap, the installer took care in future installations so that
no leaks occurred.
Additional leaks or breaks in the main line occurred three times due to heavy
equipment damage, several times due to earthslides, once due to improper
installation, and once due to theft of a twelve foot section of pipe at the
end of one of the main lines.
During the above mentioned line breaks, the maintenance personnel checked
the broken main line for residual solids accumulation. During the initial
startup period, solids accumulated sufficiently to prevent flow in one of the
two main lines. However, as the flow increased due to additional service
connections and flushing units were installed, the problem was solved.
29
-------
This confirmed the engineer's contention that some provision for flushing the
main lines is vital especially in the early stages of such a system. On four
occasions a gasoline-powered pump was utilized to flush the main lines with
lake water.
While solids accumulation presented some problems, air locking of the main
lines was the major difficulty. The original system utilized automatic and
manual air-release valves (See Figure 8). Eventually, additional manual
valves were installed with the recommendation that they be converted to auto-
matic ones when funds were available. It should be noted that during normal
operation the venting of the accumulated air and sewage gas produced a minor
odor problem.
Maintenance of the automatic air release valves was not easy because a
pressurized water source was not available at each valve for backflushing.
Several instances of valves failing to open due to solids accumulation on the
mechanical linkage arm occurred. Generally, the air release valves were a
minor maintenance problem.
One section of the main line was plagued with breaks due to the soil shifting.
Breakage due to this earth movement was later prevented by installing a
looped section of flexible pipe instead of PVC. Interestingly enough, this
loop seemed to solve the problem.
The pipe used on the main line was specified by the engineer to be a brown
color. This was done to enable a person installing a service connection to
identify it. This was especially important since the area was served by a
rural water system installed before the sewer system that also used PVC
pipe. Since the water pipe was a white color, the engineer felt that the
brown pipe would be easy to distinguish.
The possibility of requiring such pipe to be color coded and labeled "Sewer
Line" might be worth considering on future projects. Although this could
hamper material procurement by the contractor, it should prevent accidental
cross connection between sewer and water lines.
All PVC piping was specified to conform to U. S. Department of Commerce
Standard CS 256-63 for PVC 1220 SDR 26 with 160 psi working pressure at
2000 psi tensile strength and a minimum wall thickness of 0.097 inches.
Couplings and fittings of the deep-socket type were required. Backfilling
of pipe with a temperature of more than 65°F was prohibited. Testing at
150 percent of normal operating pressure (but not less than 100 psi) for at
least 30 minutes was required before completion of backfilling. After this
test and backfill completion, the pipe was required to remain full of water
under pressure. At the end of that time a leakage test was performed. The
150-psi leakage test required not more than 100 gallons per day per inch
of diameter for 12-foot pipe lengths or 75 gallons per day per inch of
diameter for 16-foot lengths of leakage.
30
-------
AIR RELEASE
PORT
MECHANICAL
LINKAGE
FLOAT
AUTOMATIC TYPE
38 1/2"-
35 1/2"-
34 1/4"
C.I. COVER
GATE VALVE
CONCRETE PIPE
FLUSHING HOSE
GATE VALVE
i;APCO" 400 VALVE
BRICK
GATE VALVE
CRUSHED STONE
MANUAL TYPE
24"-
12"
FORCE MAIN
CURB COCK/TAPPING SADDLE
5
FIGURE 8. MANUAL AND AUTOMATIC AIR RELEASE VALVES
-------
Installation of the pressure sewer system was accomplished with two types of
trenchers, a backhoe and a small bulldozer with a small crew of manual
laborers. When installing home units, similar needs existed with the
addition of a front-end loader and, when concrete units were involved, a
boom-truck.
32
-------
SECTION VIII
VACUUM COLLECTION SYSTEM
Vacuum collection, another approach to the sewage collection problem, was
attempted on a much smaller scale than the pressurized system. In this
system, a central pumping unit maintained a vacuum in the main line and
connected service lines. As the home unit filled with sewage, a valve
connecting the unit to the vacuum line opened and the sewage was drawn into
the line by the pressure differential in the line versus the atmospheric
pressure. The sewage was then to be drawn into the central station and pumped
under pressure into the pressurized main line of the rest of the system.
The primary advantage of a vacuum collection system was that smaller quanti-
ties of toilet flushing water would be required than with a conventional flush
toilet. The engineer wanted to see if an adaptation of the vacuum collection
system could offer a possible alternate solution to individual grinder-pump
units by utilizing one central vacuum pump to serve several houses.
Studies by others had indicated success in moving liquids by creating
"pockets" in the transmission lines for the liquid being moved to accumulate
into "plugs." As liquid was drawn from one pocket point to the next, the
tendency of the plug is to dissipate and the pressure to equalize. The
increased installation cost of installing pockets in the collection lines was
rejected. Instead, the collection lines were designed to remain filled with
liquid at all times.
Operation of the vacuum system was not successful. The units failed to
empty properly. Investigation into the reasons for the failure did not reveal
a specific problem. Possible causes investigated included piping leaks,
valve failure, incomplete priming of collection lines prior to start-up and
line obstructions, but no satisfactory reason was discovered.
Additional problems of water leakage into the central vacuum unit caused
repeated maintenance, and eventually the home units were replaced by pressure
pumping units and the vacuum station was abandoned. Insufficient funds pro-
hibited further investment in this area.
Specific problems or observations peculiar to the vacuum system were:
33
-------
1. Initial starting of the vacuum system requires careful priming
of the collection lines.
2. Installation of a vacuum system would require greater care
than a corresponding pressure system.
3. Leaks in the piping are difficult to locate compared to a
pressure leak.
The vacuum central station and the vacuum home units are shown in Figures
9 and 10.
34
-------
INFLUENT LINE
(FROM HOUSE)
GRINDER COMPARTMENT
GRINDER
OPENING
(SEALED)
DISCHARGE TO
CENTRAL VACUUM
STATION
LID
6" RISER
(AS NEEDED)
GATE VALVE
PRECAST
CONCRETE
CONTAINER
SHEAR GATE
(REMOVED)
OVERFLOW
DRY COMPARTMENT
SOLENOID VALVE
WATERPROOF
SEALANT
STORAGE
COMPARTMENT
LOW WATER
CUT-OFF
SWITCH
SUCTION PIPE
FIGURE 9. VACUUM UNIT
35
-------
DISCHARGE TO FORCE MAIN
CHECK VALVE
NOTE: ELECTRICAL
PANEL MOUNTED
ON POWER POLE
CHECK VALVE
5' PRE-CAST CONCRETE
CONTAINER - BASE,
WALLS, AND TOP
ASSEMBLED IN FIELD
1/4" AIR RELEASE
PIPE W/FLOAT
CONTROL
WATERPROOF
TWO CHAMBER
'PRIMER TANK
PLUG COCK
•FLOW SWITCH
.CENTRIFUGAL
PUMP
WATERPROOF
SEALANT
FIGURE 10. VACUUM PUMPING STATION
36
-------
SECTION IX
STORAGE AND TREATMENT LAGOON
Facilities for measuring, treating and disposing of the sewage flow from the
homes connected to the Grandview Lake Sewage System consisted of a parshall
flume with a punched-tape level recorder, a storage and pumping unit, a two-
celled lagoon, and an effluent irrigation system, and are shown in Figure 11.
Modular approach to the plant construction was utilized by the engineer in an
attempt to minimize construction costs. Operation of the plant was to consist
of measuring the influent flow, storage of the sewage, irrigation of the
lagoon effluent, and discharge of runoff from the irrigation area of not more
than an amount equal to the natural runoff from rainfall during the irri-
gation period.
The degree of success of the treatment facilities was encouraging but fail-
ures in the physical facilities constructed created interruptions and curtail-
ment of the effective study of the treatment process.
The parshall flume with a punched-tape level recorder was the first piece of
equipment through which the flow passed in the treatment facilities. The
parshall flume liner was fabricated by a local metal fabrication company and
precast into a concrete rectangular channel and provided with a plywood cover.
This greatly reduced the cost anticipated on such a structure, and several
contractors indicated an interest in using such an installation on other
projects. Field installation was limited to setting the unit in place,
connecting the required piping, constructing the level recorder pit, and
installing the recorder. There were two problems that affected the successful
operation of the level recorder. There was rapid accumulation of ground up
paper particles on the liner and the flume did not drain properly to prevent
the buildup of liquid in the flume. The daily flow data were collected during
a period when daily cleaning of the liner was performed by the SIECO mainte-
nance men to solve drainage problems. A source of flushing water would have
made maintenance of the unit easier. Any attempt to measure ground sewage
flows must take into account this paper accumulation problem.
After passing through the parshall flume, the sewage was stored in a
1,000-galIon storage tank connected to a pumping unit. The pumping utilized
a low head high-capacity Flint and Walling centrifugal pump controlled by
probes in the storage tank. A sampling valve was provided so that a com-
posite sampler could draw a sample representative of the total flow entering
the plant in a 24-hour period. Paper particles fouled the control probes
and sampling valve repeatedly and groundwater infiltration could not be
completely eliminated.
37
-------
O-J
00
VALVE
NO. 1
PUMPING
UNIT NO. 1
MAIN LINE FROM SYSTEM
PARSHALL FLUME
(HEAD RECORDER)
SURGE TANK
BYPASS NO. 2
RETURN LINE
^•»
"VALVE
LVALVE NO.4
'PUMPING UNIT NO. 2
'VALVE NO.2
'VALVE NO.3
RUNOFF COLLECTION TANK
DISCHARGE TO STREAM
PUMPING UN IT NO. 4
/RETURN NO.2
0/ALVE NO.7
^
VALVE NO.6
IRRIGATED
HAY FIELD
PUMPING
UNIT NO. 3
RUNOFF
COLLECTION
TANK
FIGURE 11. PLAN LAYOUT OF TREATMENT PLANT
-------
A gravity overflow line was provided so that the storage tank and pumping
unit could be bypassed. It was designed to be used only when the flow
entering the plant exceeded the capacity of the pumping unit. This unit
failed to work on three occasions. The first time there was an air lock in
the pipe which was remedied by providing an air relief pipe that discharged
back into the channel behind the recording device on the parshall flume. The
second time a piece of heavy equipment had driven over the line and caused a
break. The third time a dead rabbit was found in the opening to the line.
It was never determined how the rabbit got into the system.
The pumping unit No. 1 and the bypass line were connected to a common line
that discharged into the bottom of the primary cell of the lagoon. This
pipe operated well for about 10 months but then became clogged with an
unknown object or solids. Attempts to free the pipe failed, and a new pipe
was installed.
The lagoon was a two-celled storage facility. The primary cell, the cell
receiving the system flow, was designed as a facultative pond, combining
anaerobic and aerobic biological activity. The raw sewage flow was to be
introduced into the lower (anaerobic) level of the lagoon. Short-circuiting
of the lagoon was minimized by use of a tee on the influent line. The upper
(aerobic) level of the primary cell was to be utilized for irrigation into
the hay crop and for sealing off any odor from the anaerobic section. The
second cell was to be used for irrigation storage and polishing.
Flows anticipated at the plant were computed as follows:
22 year-around homes @ 50,000/yr = 1,100,000 gallons
36 weekend homes @ 50,000/yr x 1/3 = 600,000 gallons
Estimated annual flow = 1,700,000 gallons or 5.2 acre feet
Actual flow figures collected in 1972, shown in Tables 2 through 6, indicated
a flow of about 60,000 gallons per home per year.
The primary cell was designed for a total volume of 1,070,000 gallons.
Surface aerators were recommended at a future date as needed to maintain the
upper zone of the primary cell in an aerobic condition. The secondary cell
was designed for a storage capacity of 995,000 gallons. The two cells
therefore had a total capacity of more than 2 million gallons. Space was
reserved at the site for another 1-acre lagoon for future needs.
Initial filling of the primary lagoon was anticipated to take approximately
one year under ideal conditions. However, due to the construction schedule
of the facility, waste was discharged into the lagoon in November 1970. Since
initial flow was limited, due to slow installation of the home units, the
anaerobic section and a portion of the aerobic section of the primary cell of
the lagoon was filled with 102,000 gallons of lake water pumped into the
system. This was done to prevent damage to the lagoon piping during freezing
and thawing of the lagoon surface.
39
-------
TABLE 2
1972 MONTHLY FLOW DATA SUMMARY
Month
July
August
September
October
November
Total
Flow
CD
540,330
429,629
501,840
451,732
501,150
Average
Flow
(GPM)
12.1
9.6
11.6
10.1
11.6
Average
Flushing
Peak Flow
(GPM)
20.9
25.0
19.3
20.8
30.7
Highest
Normal
Peak Flow
(GPM)
108.0
100.0
73.0
96.0
258.0
Number
of Active
Home Units
92
92
92
92
93
Average
(GPD)
189.5
150.2
182.0
158.1
179.6
Flow per Unit
(GPM)
.132
.105
.126
.109
.125
NOTE: DURING NOVEMBER 1972, ON SIX OCCASIONS THE NORMAL PEAK FLOW EXCEEDED 100 GPM. DAILY
INVESTIGATION BY FIELD PERSONNEL CONFIRMED PROPER OPERATION OF THE RECORDING EQUIPMENT
AND NO BUILDUP IN THE PARSHALL FLUME DUE TO LINE OBSTRUCTIONS. FOR SUCH A FLOW THE
PRESSURE IN THE MAIN LINE WOULD EXCEED THE SHUT OFF HEAD OF THE CENTRIFUGAL PUMPS USED
ON THE PROJECT. THIS WAS ATTRIBUTED TO THE SIMULTANEOUS OPERATION OF THE POSITIVE
DISPLACEMENT E-l AND MOYNO TYPE PUMPS.
(1) Adjusted for any days when recorder was not in operation.
-------
TABLE 3
DAILY FLOW DATA
FOR JULY AND AUGUST, 1972
Date
7-15
7-16
7-17
7-18
7-19
7-20
7-21
7-22
7-23
7-24
8-05
8-06
8-07
8-08
8-09
8-10
8-11
8-12
8-13
8-14
8-15
8-16
8-17
8-18
8-19
8-20
8-21
8-22
8-23
8-24
8-25
8-26
8-27
8-28
8-29
8-30
8-31
Total
Flow
(GPP)
15,000
12,400
23,200
15,700
18,400
14,400
14,400
23,200
18,800
18,800
13,100
14,100
12,500
12,500
12,400
11,200
11,500
16,600
13,700
12,700
13,700
14,000
20,200
12,400
14,800
13,100
14,800
15,800
13,000
13,500
14,800
15,000
18,800
13,800
12,000
12,400
11,800
Average
Flow
(GPM)
10.4
8.6
16.1
10.9
12.8
10.0
10.0
16.1
13.0
13.0
9.1
9.8
8.7
8.7
8.6
7.8
8.0
11.5
9.5
8.8
9.5
9.7
14.0
8.6
10.3
9.1
10.3
11.0
9.0
9.4
10.3
10.4
10.3
9.6
8.3
8.6
8.2
Flushing
Peak Flow
(GPM)
17.0
24.0
29.0
33.0
23.0
17.0
15.0
17.0
13.0
21.0
17.0
24.0
23.0
24.0
17.0
21.0
29.0
26.0
21.0
19.0
45.0
31.0
31.0
40.0
37.0
38.0
17.0
36.0
24.0
17.0
23.0
13.0
21.0
21.0
21.0
17.0
21.0
Normal
Peak Flow
(GPM)
50.0
85.0
39.0
70.0
39.0
85.0
50.0
108.0
68.0
77.0
35.0
39.0
61.0
39.0
28.0
31.0
31.0
54.0
35.0
42.0
31.0
77.0
35.0
68.0
77.0
35.0
42.0
100.0
42.0
39.0
50.0
68.0
68.0
50.0
39.0
35.0
50.0
41
-------
TABLE 4
DAILY FLOW DATA
FOR SEPTEMBER, 1972
Date
9-01
9-02
9-03
9-04
9-05
9-06
9-07
9-08
9-09
9-10
9-11
9-15
9-16
9-17
9-18
9-19
9-20
9-21
9-22
9-23
9-24
9-25
9-26
9-27
9-28
9-29
9-30
Total
Flow
(GPP)
12,400
15,400
16,400
18,400
13,700
12,200
13,100
13,100
15,400
16,400
23,200
13,100
13,000
16,000
14,800
11,800
13,100
17,700
25,500
24,400
20,200
21,300
20,200
18,600
20,000
16,600
15,700
Average
Flow
(GPM)
8.6
10.7
11.4
12.8
9.5
8.5
9.1
9.1
10.7
11.4
16.1
9.1
9.0
11.1
10.3
8.4
9.4
12.3
17.7
16.9
14.0
14.8
14.0
12.9
13.9
11.5
10.9
Flushing
Peak Flow
fGPMl
15.0
21.0
17.0
24.0
31.0
17.0
21.0
19.0
24.0
17.0
17.0
15.0
13.0
24.0
13.0
7.0
13.0
15.0
19.0
26.0
29.0
19.0
19.0
17.0
40.0
13.0
15.0
Normal
Peak Flow
fGPMl
26.0
31.0
26.0
37.0
29.0
26.0
55.0
37.0
37.0
43.0
37.0
31.0
26.0
31.0
26.0
24.0
31.0
37.0
55.0
73.0
43.0
49.0
66.0
55.0
37.0
43.0
40.0
42
-------
TABLE 5
DAILY FLOW DATA
FOR OCTOBER, 1972
Date
10-01
10-02
10-03
10-04
10-05
10-15
10-16
10-17
10-18
10-19
10-20
10-21
10-22
10-23
10-24
10-25
10-26
10-27
10-28
10-29
10-30
10-31
Total
Flow
CGPDI
18,400
18,600
18,400
17,900
16,400
12,700
15,400
13,200
12,500
12,400
12,400
12,100
11,800
15,000
13,500
13,500
14,400
14,000
12,800
13,800
16,000
15,000
Average
Flow
CGPM)
^\JJ. !•*/
12.8
12.9
12.8
12.4
11.4
80
. o
10.7
90
. £
o 7
o • /
8.6
8f.
• o
8 A
. T-
8 2
O • in
10.4
Q 4
«J • "
9.4
10.0
Q 7
y . /
Q Q
g!&
11.1
10.4
Flushing
Peak Flow
fGPM)
39.0
35.0
35.0
24.0
18.0
30.0
25.0
25.0
25.0
35.0
20.0
20.0
32.0
25.0
23.0
16.0
20.0
17.0
20.0
27.0
20.0
30.0
Normal
Peak Flow
(GPM)
68.0
77.0
54.0
68.0
61.0
41.0
41.0
44.0
38.4
41.0
44.0
44.0
35.0
50.9
50.9
30.0
35.0
58.0
35.0
41.0
93.3
96.0
43
-------
TABLE 6
DAILY FLOW DATA
FOR NOVEMBER AND DECEMBER, 1972
Date
11-01
11-02
11-03
11-04
11-15
11-16
11-17
11-18
11-19
11-20
11-21
11-22
11-23
11-24
11-25
11-26
11-27
11-28
11-29
11-30
Total
Flow
(GPP)
14,300
17,100
13,700
12,400
12,200
15,000
15,400
30,000
27,900
17,300
14,700
16,000
15,100
18,400
19,900
16,100
15,400
16,400
10,100
16,700
Average
Flow
(GPM)
Flushing
Peak Flow
(GPM)
9.9
11.9
9.5
8.6
8.5
10.4
10.7
20.8
19.4
12.0
10.2
11.1
10.5
12.8
13.8
11.2
10.7
11.4
7.0
11.6
29.0
31.0
44.0
23.0
21.0
26.0
34.0
26.0
76.0
29.0
29.0
29.0
19.0
26.0
34.0
31.0
26.0
31.0
26.0
24.0
Normal
Peak Flow
(GPM)
101.0
80.0
47.0
41.0
55.0
59.0
84.0
108.0
257.0
134.0
49.0
52.0
43.0
49.0
73.0
62.0
62.0
37.0
76.0
52.0
12-01
12-02
12-03
19,300
16,800
15,700
13.4
11.7
10.9
26.0
29.0
40.0
59.0
88.0
55.0
44
-------
During the winter the lagoons froze over and some of the neighborhood
children went riding mini bikes on the ice. Fencing the facility site was
not sufficient to prevent access. The Lot Owners decided that there should
be an additional fence erected around the lagoons as soon as possible.
By June 30, 1971 there were twenty-three homes discharging into the lagoon.
This flow coupled with surface run-off had caused sufficient accumulation of
liquid to enable irrigation to be applied to the hay crop the week of
July 18, 1971.
Operating procedures for the lagoon-irrigation facilities were designed for
maximum flexibility. Descriptions of these procedures which follow are
keyed to Figure 11. Under normal conditions the influent wastewater, after
passing through the parshall flume, went first to the surge tank (valve #1
open). When the surge tank reached a set level, pumping unit #1 pumped the
surge tank contents to lagoon 1. During power outages or peak flows which
exceeded the 4-inch line capacity, the influent automatically bypassed to
the lagoon via bypass #1. Lagoon 2 was designed for use during periods of
high flow and during the winter for prolonged storage. The system also had
the capability for recirculation from lagoon 2 to lagoon 1 by closing valves
#2, 3, and 4, opening valve #5, and operating pumping unit #2. In addition,
lagoon 1 could be mixed by closing valves #2 and 4, opening valves #3 and 5,
and operating pumping unit #2.
Irrigation of the hay field could be accomplished from either lagoon 1 or
lagoon 2. Lagoon 1 effluent could be used (minimum depth was maintained) by
closing valves #2 and 5, opening valves #3 and 4, and operating pumping unit
#2. Lagoon 2 effluent could be used by closing valve #5, opening valve #4,
and operating pumping unit #2.
The non-irrigated hay field runoff was collected, sampled and metered to the
stream via pumping unit #4. The volume of runoff discharged was then used as
the "target" volume to be sampled and metered to the stream from the irrigated
hay field runoff-collection tank via pumping unit #3 with valve #6 open and
valve #7 closed. Any excess over the target volume in the irrigated field
runoff collection tank was recycled to the sprinkler irrigation system by
using pumping unit #3 with valve #6 closed and valve #7 opened.
Surface runoff continued to be a problem due to soil erosion into the drain-
age ditches around the lagoon. Maintenance of the ditches became critical
and required additional grading by the contractor.
On January 9, 1972 a fault in the levee (See Figures 12, 13, 14, 15, and
16) around the secondary lagoon broke and approximately 750,000 gallons of
irrigation liquid ran out through the break and eventually into the stream.
This was reported promptly to the State Board of Health and the receiving
stream was tested for contamination. A 5-day BOD test of the irrigation
liquid just prior to the break was 6.5 mg/1. The 5-day BOD's taken at
selected points in the stream ranged from a high of 4.2 mg/1 at the point of
discharge into the stream to 1.3 mg/1 1 mile downstream. A slight odor was
evident 1 mile downstream but not evident 1.8 miles downstream.
45
-------
700
SLOPE 2.5:1
695
DRAINAGE DITCH
FIGURE 12. LAGOON LEVEE FAILURE
SOIL BORING LOCATION
AREA OF LEVEE FAILURE
1+1 STATION OF X-SECTION
•^•^MMB
-675—ORIGINAL GRADE ELEVATION
-------
700:
FIGURE 13. LAGOON LEVEE FAILURE X-SECTIONS AT STATIONS
0+00 AND 0+10
FIGURE 14. LAGOON LEVEE FAILURE X-SECTIONS AT STATIONS
0+20 AND 0+45
47
-------
33JL
^iiLf Trisfe
•1*150:-. :
.. i.,,,..: .
-M-rt~
120-T>^Mfi1- -1^0--^
_l..;.4-i.:_!..:.,. pwh,-,!...'... .
_.7WiuMnl
. . ._. . ,. TJ
0; -•?<)• • 40 - - 60^-' r-Sto
FIGURE 15. LAGOON LEVEE FAILURE X-SECTIONS AT STATIONS
1+00 AND 1-1-50
FIGURE 16. LAGOON LEVEE FAILURE X-SECTION AT STATION 1+65
48
-------
Investigation into the cause of the slide revealed:
1. Irrigation of the plant effluent had been curtailed due to poor weather
conditions and soil conditions.
2. The lagoons were full to the point of utilizing about one-third of
the freeboard available.
3. Recent rains had kept the levee around the lagoon saturated.
4. The layer of shale noted in the original core borings was removed
by the contractor in Cell I and clay compacted in its place. In
the area of the levee, the contractor cut through the shale layer,
removed the shale, and cut and constructed the levee key below that
layer.
Soil conservation officials and the engineers observed that apparently a
second layer of shale (soapstone) existed beneath the two lagoons that was
not revealed in core boring No. 8 (See Figure 17) taken prior to construction.
This material became saturated and very slick. The weight of the levee and
the impounded liquid caused the entire section of the levee to slip down
the soapstone layer. A solution to the problem proposed that a series of
drains be installed in the soapstone layer and in the toe of the levee.
This was deemed too costly and a larger lagoon was built at a different
location on the plant site.
The new lagoon was designed to provide storage of four months of flow from
one hundred houses plus rainfall. The lagoon had a surface area of 1.78
acres and had a total depth of ten feet of which 2.4 feet was freeboard.
Additional irrigation area was also recommended at that time (See Figure 18).
Maintenance of the treatment plant proved to be much higher than anticipated
in the original design estimate. The fact that the treatment process was
simple did not enable limited maintenance of the equipment. A higher initial
installation cost with an automated irrigation system might have resulted in
lower overall costs.
49
-------
i
A\\\\
HOLE
NO.7
°'!
I
HOLE
NO.8
710
705
700
695
690
685
SILT
SILTY-CLAY
CLAY
SHALE
FIGURE 17. LAGOON SITE BORING LOGS
50
-------
GRANDVIEW LAKE
SYSTEM
MAIN LINE
ABANDONED
NON-IRRIGATET
FIELD
AIR RELEAS
VALVE
pvc PARSHALL FLUME
2 1/2" SUCTION FROM ^
PRIMARY LAGOON
ABANDONED
SURGE TANK t
ABANDONED
IRRIGATION
FIELD
EXISTING
PUMPINC
UNIT
NEW SECONDAR
STORAGE LAGOON
PROPOSED
IRRIGATION
FIELD
FIGURE 18. REVISED TREATMENT PLANT LAYOUT
-------
SECTION X
LAGOON EFFLUENT IRRIGATION DATA
As originally proposed, the liquid from the lagoons was to be irrigated onto
a hay crop at regular intervals throughout the summer months. A 1-acre irri-
gation field and similar-sized control field were to be utilized to determine
the amount and strength of runoff from irrigated and non-irrigated land. No
discharge from the irrigated field was planned other than an amount equal to
that from the non-irrigated field. The volume of the discharge was equalized
by re-irrigation of any runoff from the irrigated field. A partial failure
of the irrigation field crop due to flooding prohibited total operation as
originally proposed. Additional irrigation areas were utilized as needed,
but conclusions as to the effectiveness of such application in relation to
ground slope, type of vegetation, frequency of application were drawn.
Individual applications to the 1-acre field over a 24-hour period ranged
from 15,400 gallons to 52,100 gallons or a depth of 0.57 to 1.92 inches.
The normal operating level was about 24,000 gallons or 0.88 inch. The
period of recovery between applications varied with temperature, humidity
and wind velocity.
Total crop irrigation during 1971 was as follows:
Month Gallons
July 15,200
August 31,600
September 7,500
October 14,260
November 2,700
Total 71,260 gallons
Prior to the failure of the lagoon levee an auxiliary irrigation system was
laid out in the woods near the treatment plant. In 1971, 74,800 gallons were
pumped onto the vegetation without any runoff to the stream. Therefore, the
total volume of lagoon effluent discharged to the land in 1971 was 146,060
gallons.
The irrigation system was then moved in December, 1971 to another location
where vegetation was thicker than at the previous location. Further damage
to the lagoon levee was prevented by irrigating to this area in addition to
the irrigated hay field in 1972. Irrigation figures for 1972 are as follows:
52
-------
M°nth Gallons
August 400,625
September 676,332
October 52,150
Total 1,109,107
As noted earlier, when the new lagoon was designed it was recommended that
a larger area (5.5 acres) be used for irrigation to effectively consume the
liquid volume entering the plant.
The lezbedeza hay crop intially used was killed off by excess water, but a
fescue mixture used the second year was hardier. It was found by the
operators that the initial application to vegetation areas far exceeded the
average load applicable without runoff to the stream. Multiple applications
created washed areas on slopes greater than 4 to 1 and pooling in depressions
prevented any new growth. The best area for irrigation was one which had
dense grasses and trees less than 15-feet tall.
Ideally, the frequency and intensity of application would have been no
greater than 25,000 gallons every third day at the Grandview plant due to
soil conditions. By anticipating a rotation of irrigation areas to allow
such a schedule, the engineer could minimize runoff. Of course, naturally-
wooded areas might utilize a greater or lesser volume of liquid per acre
due to type of vegetation, ground slope, soil type, etc. It was the
engineer's experience that the capability for irrigating several times the
average daily irrigation volume was necessary for disposal due to weather
factors. One acre could be used to dispose of 1,920,000 gallons [24,000 x
1/3 (30 days) x 8 months] of liquid under ideal conditions. However, a
design factor of 1,303,315 gallons per acre or 48-inches of liquid per year
was used in sizing the new irrigation area.
53
-------
SECTION XI
LABORATORY ANALYSES
During the research period of the Grandview Lake Sewage Project, specific
laboratory tests were performed to answer the following:
1. What was the strength of the waste at the home pumping
units?
2. What was the strength of the waste entering the plant?
3. How effective was the lagoon treatment?
4. How effective was the irrigation step in reducing the
strength of the lagoon effluent?
5. How did the runoff from the irrigated field compare to
the runoff from the non-irrigated field?
The procedures followed for testing the sewage samples conformed to
Simplified Laboratory Procedures for Wastewater Examination, published by the
Water Pollution Control Federation (WPCF Pub. No. 18).
Specific tests conducted on the samples collected were:
1. Biochemical Oxygen Demand CB.O.D.)
2. Suspended Solids
3. Orthophosphates
4. Ammonia-Nitrogen
5. Nitrite-Nitrogen
6. Nitrate-Nitrogen
7. Chemical Oxygen Demand (C.O.D.)
Evaluation of the various samples resulted in the following conclusions:
The strength of the sewage found in the home units varied widely with unit
type. The septic tank effluent systems had the lowest concentrations of BOD,
COD and suspended solids, but also had the most pronounced odor. A higher
strength waste was collected at the various home units than was seen entering
the plant. This higher strength was to be expected since no sedimentation
(septic tank) was provided prior to the pumping units.
After the levee failure, lack of aeration or recirculation and the reduced
storage capacity caused the upper portion of the primary cell to turn septic
toward the end of the research period. Excellent treatment was obtained by
the overall treatment sequence, as evidenced by the field runoff comparisons,
shown in Table 7.
Although the data are limited a number of consistencies are evident. First,
the plant influent, being a mixture of grinder-pump and septic tank effluent
54
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Location
ONSITE
Grinder-Pumps
Septic Tank Effluent
PLANT INFLUENT
LAGOON 1 EFFLUENT
FIELD RUNOFF
Irrigated
Non-Irrigated
TABLE 7
ANALYTICAL SUMMARY
Number of
Samples
Composite
or Grab
Average Concentration, mg/1
BOD COD SS P04 N(l)
3
1
5
3
3
3
G
G
4C;1G
G
G
G
360
110
216
128
9
11
560
190
413
275
49
59
470
95
170
140
8
48
31
22
40
32
6
NIL
41
44
39
22
15
6
(1) Nitrogen data represent sum of NH3, N02 and NO^ results, expressed as N.
55
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pump flows, generally has measured pollutant concentrations intermediate
between the two sources. Secondly, the lagoon effluent does demonstrate some
treatment efficiency when compared to the influent, including some nutrient
reduction. Finally, the runoff from the irrigated hay field was of somewhat
better quality than the non-irrigated field with respect to BOD, COD and
suspended solids. An increase in nutrients appears to exist, but when
compared to the plant influent, a significant reduction in nutrients appears
to take place during the treatment sequence.
A complete list of analytical results is given in Table 8.
Even the limited scope of the testing on this project confirmed that irriga-
tion of treatment plant effluent was an effective method of disposing of
domestic sewage.
56
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TABLE 8
ANALYTICAL DATA
(1972)
Location (T
(#)
1
2
3
4
5
6
Sample
) Date
10/17
10/17
11/1
11/1
9/5
9/14
11/30
12/7
12/11
9/5
10/17
11/1
7/23
10/17
11/1
7/23
10/17
11/1
Type
(CorG)
G
G
G
G
G
C
C
C
C
G
G
G
G
G
G
G
G
G
Parameter Measured (Concentrations in mg/1)
BOD5
690
180
210
110
305
185
310
100
180
170
95
120
3
9
16
4
19
10
COD
707
460
508
191
533
457
462
230
382
337
207
282
58
33
56
62
61
44
SS
1080
145
175
95
268
136
264
80
102
116
140
165
11
6
6
7
60
78
m4
23
32
37
22
28
59
48
32
34
27
28
42
NIL
2.5
16
NIL
NIL
NIL
N03-N
7
7
5
4
1.5
9
0.2
4
0.3
1
2
5
-
1.8
18
-
1.8
4
N02-N
NIL
NIL
NIL
NIL
NIL
1.0
NIL
NIL
NIL
NIL
NIL
NIL
_
NIL
NIL
_
NIL
NIL
NH--1*
70
17
18
40
16
47
45
34
39
19
20
19
0.7
0.6
8.0
0.8
0.2
5.0
Location: 1 - Grinder Pumps
2 - Septic Tank Effluent Pumps
3 - Plant Influent
4 - Lagoon 1 Effluent
5 - Irrigated Field Runoff
6 - Non-Irrigated Field Runoff
57
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SECTION XII
COSTS AND DISCUSSION
One of the anticipated results of the Grandview Lake Research and
Demonstration Project was to provide inexpensive sewers to rural areas. It
appears that a price of about $600 to $1,500 for each individual grinder-pump
can be anticipated. The engineer originally felt that a unit could be pro-
duced for less than $500. Since present financing limitations per customer
in sparsely populated areas are such that only about one-third of the borrowed
monies can realistically be applied to a grinder-pump unit, i.e., two-thirds
would be applied to system piping and treatment facilities, this early esti-
mate would have enabled greater application of the pressure sewer approach.
There is the possibility that free market conditions may force the price of
the grinder-pump units down. This would make future projects more feasible.
It was found that a great amount of engineering time, especially in the field,
and close construction inspection was needed during installation and start-up
of the system and home units. It is anticipated that as contractors become
better acquainted with pressure sewer systems that this would be minimized.
The impact of the sewer system being available to the lot owners was best seen
in two indicators; the ratio of permanent residences to part-time residences
and the purchase price of lots before and after the pressure sewer install-
ation. When the system operation was begun in November 1970, there were 22
houses that were occupied on a full-time basis and 36 on a part-time basis.
By June 13, 1972, the number of part-time occupancies was negligible and 100
permanently-occupied homes were anticipated in the area served by the initial
system. During the same period of time the value of the lots had increased as
much as 45 percent. The reluctance of potential buyers to locate where sewer
facilities were not available was overcome by the pressure sewer system.
The construction cost summary for the pressure main is presented in Table 9.
In addition, the treatment facility, including the lift station capital cost
was $32,142. Therefore, the total capital cost per home would be the sum
of the pressure main and treatment facility, divided by the number of homes
served, added to the cost of the onsite facility of each homeowner. The
approximate costs of the various units employed in the study are given in
Table 10. Since the number of operating units varied throughout the study
and since a number of original units were replaced during the course of the
project, an exact average cost is not easily computed. For example, if the
original 58 homes were chosen, the average cost of the main and treatment
facilities per home was $1,166, plus the onsite cost. If the ultimate pro-
jection of 100 homes were chosen, the average cost drops to $676, plus the
onsite facilities.
58
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TABLE 9
PRESSURE SEWER COST BREAKDOWN
Item
5-inch PVC (SDR 26)
3.5-inch PVC (SDR 26)
3-inch PVC (SDR 26)
2-inch PVC (SDR 26)
Blacktop Road Repair
Manual Air Release Valves
Automatic Air Release Valves
Mainline Gate Valves § Boxes
Quantity
Unit
Cost
Total
635 ft
11,475 ft
14,155 ft
1,230 ft
40 ft
6
4
2
$2.00/ft
1.10
1.10
0.90
3.00
125.00 ea.
200.00
100.00
$ 1,270
12,622
15,571
1,107
120
750
800
200
Total Cost* $32,440
*Bid cost, not including $1,000 vacuum collection station.
Actual cost, including vacuum station, was $33,044.
Final cost including additional items such as an extension of the main,
line relocation, county blacktopping and rock excavation was $35,491.
59
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TABLE 10
APPROXIMATE HOME UNIT COST COMPARISON
Type of Unit
Septic Tank Effluent Pump
and Tank (3)
Hydromatic GP
Environment One GP
Tulsa GP
Moyno GP
Flushing Unit with
1000 gallon Tank
Delivered
Cost(l)
670
920
950
600
600
750
Cif requiret
ft. of 1-inc
Installation
Cost
200
200
200
200
200
450
.).«.. 11 »c
:h PVC service
Service Line §
Connection Cost (2)
160
160
160
160
160
200 (4)
:illary items for comple
line, curb cock, and al
Total Cost
1030
1280
1310
960
960
1400
te system,
1 other
(2) serviceline
(3) When new installation, approximately $400 must be added for septic tank
(4) Larger (1.5-inch) service lines generally required for flushing units.
-------
Due to the experimental nature of the project, an unusual amount of public
relation work had to be done on the Grandview project. The engineer was very
fortunate to have a Utility Board composed of engineers and businessmen
familiar with research and development projects. They understood that every-
thing was not going to function perfectly from the start. They did an
excellent job of explaining to the homeowners that problems would arise, but
that they would be dealt with as soon as possible. Generally, the attitude
of the homeowners was very good. They realized that the "bugs" had to be
worked out of the system and there would be some inconveniences. The alter-
native to the project, septic systems leaking into yards and the lake, no
doubt was an influencing factor in their attitude.
The initial concept of the engineer was to develop a fractional horsepower
grinder-pump unit with parts that were readily available to the homeowner in
the event of malfunction. The horsepower was to be kept to a minimum to help
reduce the homeowner's electrical bill. It became very evident during the
project that the homeowner was neither interested in a low electric bill
nor able to service the unit himself. He simply wanted a maintenance-free
sewer system.
The community's primary goal was to obtain a functional sewer system. The
research project funds provided a start toward that goal, but were never
intended to be limited to that use. Knowledge was gained from the failures
as well as the successful parts of the project.
61
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SECTION XIII
REFERENCES
1. Waller, D. H., "Experience with Grinding and Pumping of Sewage from
Buildings," Tech. Memo Nos. 3 and 3A, ASCE Project (1967).
2. Farrell, R. P., Anderson, J. S., and Setser, J. L., "Sampling and
Analysis of Waste Water from Individual Homes," 67-MAL-3, General
Electric Company for ASCE Combined Sewage Separation Project (1967).
3. Linaweaver, F. P., Jr., Geyer, J. C. and Wolff, J. B., "Final and
Summary Report on Residential Water Use Project," Johns Hopkins
University (1966).
4. Tucker, L. S., "Sewage Flow Variation in Individual Homes," Tech.
Memo. No. 2, ASCE Combined Sewage Separation Project (1967).
62
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SECTION XIV
PUBLICATIONS
1. Rees, S. M., "Wastewater Disposal Plan to Protect Recreational Lake,"
Public Works, 103, No. 4, pp. 88-91 (1971).
2. Sanson, R. L., "Design Procedure for a Rural Pressure Sewer System,"
Public Works, 105, No. 10, pp.86-87 (1973).
3. Hendricks, G. F., and Sanson, R. L., "Pressure Sewer Design Procedure,"
Water S Sewage Works, 122, No. 11, pp. 53-54 (1973).
4. Hendricks, G. F., "Pressure Sewer System and Treatment at Grandview
Lake, Indiana," Proceedings of Ohio Home Sewage Disposal Conference,
Columbus, Ohio, January 79-31, 1973.
5. Hendricks, G. F., "Pressure Sewer System and Treatment, Grandview
Lake, Indiana," Paper presented to Annual Meeting of American Society
of Agricultural Engineers, Pullman, Washington, June 27-30, 1971.
63
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SECTION XV
GLOSSARY
English units
( ) X
Length
mile
foot
inch (")
Area
acre
Volume
gallon
Mass
pound
Volume rate of flow
gallon/day (GPD)
gallon/minute (GPM)
Volume loading rate
gallon/acre
Pressure
Conversion factor
C )
1.609
0.305
25.4
0.404
3.786
0.454
0.0038
0.0631
0.0094
pound(f)/square inch(psi) 6.895
Power
horsepower
0.7457
Metric
( )
kilometer
meter
millimeter
hectare
liter
kilogram
meter /day
liter/second
meter /hectare
kilopascal
kilowatt
64
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/2-75-072
3. RECIPIENT'S ACCESSIOWNO.
TITLE AND SUBTITLE
5. REPORT DATE
ECONOMICAL RESIDENTIAL PRESSURE SEWER SYSTEM
WITH NO EFFLUENT
December 1975 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
AUTHOR(S)
8. PERFOBMING ORGANIZATION REPORT NO.
Gerald F. Hendricks and Stephen M. Rees
PERFORMING ORGANIZATION NAME AND ADDRESS
SIECO, Inc., Columbus, Indiana (for)
Grandview Lot Owners Association
RR6 - Grandview Lake
Columbus, Indiana 47201
10. PROGRAM ELEMENT NO.
1BB035/21-ATC/004
115«Qt*Btte8CX/GnANT NO.
S801041
2. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final - 4/69 to 11/72
14. SPONSORING AGENCY CODE
EPA-ORD
5. SUPPLEMENTARY NOTES
6. ABSTRACT
An economical pressure sewer system with no polluting effluent was designed,
constructed, and monitored for effectiveness. The elimination of groundwater
infiltration and restrictive elevation tolerances associated with a conventional
gravity sewer system enabled this type of sewer system to be installed and to
function economically. The treatment process, aerobic and anaerobic lagoon storage
with subsequent irrigation of the effluent, yielded no more than normal volume of
runoff.
Operational problems with the pressure system resulted from inefficient home grinder-
pump units. These problems were greatly reduced when commercially manufactured home
units became available. The treatment process functioned as anticipated. Because of
the new sewer system, summer homes become year around residences and new home con-
struction exceeded expectations. As a result, the initial irrigation area proved
inadequate for handling the actual flows and additional irrigation area was made
available at a later date.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lOENTIFIERS/OPEN ENDED TERMS
COSATi Field/Group
Sewers
Sewage
Sewage treatment
Sewage disposal
Pressure sewers
Lagoons
Effluent irrigation
13B
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
73
20. SECURITY CLASS (Thispagt)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
65
OUSGPO: 1976 — 657-695/5358 Region 5-11
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