Pressure Sewer Demonstration at the Borough of Phoenixville, Pennsylvania


 EPA-R2-73-270
                       Environmental Protection Technology Series
 July 1973
 PRESSURE SEWER  DEMONSTRATION

AT THE BOROUGH OF

 PHOENIXVILLE, PENNSYLVANIA
                                 Office of Research and Development


                                 U.S. Environmental Protection Agency

                                 Washington, D.C. 20460

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            RESEARCH REPORTING SERIES
Research reports of the  Office  of  Research  and
Monitoring,  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
   U.  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.

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EPA-R2-73-270
July 1973
PRESSURE SEWER DEMONSTRATION AT THE

BOROUGH OF PHOENIXVILLE, PENNSYLVANIA
by

George Mekosh
Daniel Ramos
Project No. 11050 FOU
Project Officer

James F. Kreissl
U.S. Environmental Protection Agency
National Environmental Research Center
Cincinnati, Ohio 45268
Prepared for

OFFICE OF RESEARCH AND MONITORING
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D. C. 20460
For sale by the Superintendent of Becflfaents, U'.S.,G
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EPA REVIEW NOTICE
This report has been reviewed by the Environmental Protection
Agency and approved for publication. Approval does not signify
that the contents necessarily reflect the views of the Environ-
mental Protection Agency, nor does mention of trade names or
commercial products constitute endorsement or recommendation for
use.
ii
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ABSTRACT
A site was selected at the Borough of Phoenixville, Pennsylvania,
which provided a maximum variable exercise of a pressure sewer
system. The site consisted of five residences spread over more than
one-half mile in hilly and predominantly shale-based terrain. The
residences varied from a small house to a multiple-unit apartment
house. The apartment house is more than half a mile in distance
and 60 feet in elevation below the existing conventional gravity
sewer inlet point.

The project proved over a six-month period that a multiple residence
pressure sewer system can adequately store peak loads of wastewater
and grind and pump wastewater through small-diameter plastic pipe
to the existing conventional gravity sewer. During the project,
data was collected which provided information concerning the in-
stallation, operation and maintenance of the system, its technical
performance, the variations in that performance during the six-
month period and the characteristics of the wastewater as delivered
to the existing gravity sewer.

This report was submitted in fulfillment of Project Number 11050
FOU under the sponsorship of the Office of Research and Monitoring,
United States Environmental Protection Agency by the Borough of
Phoenixville, Pennsylvania
iii
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CONTENTS

SECTION PAGE

I CONCLUSIONS 1

II RECOMMENDATIONS 3

III INTRODUCTION 5

IV PROJECT OBJECTIVES 7

V SYSTEM LOCATION 9

VI GENERAL PRESSURE SEWER COMPONENT 11
DESCRIPTION

VII PHOENIXVILLE SYSTEM DESCRIPTION 17

VIII DEMONSTRATION RESULTS 33

IX ACKNOWLEDGEMENTS 57

X APPENDICES 59
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FIGURES
1 AREA MAP OF PHOENIXVILLE

2 TYPICAL INSTALLATION

3 MOYNO FS-44 PUMP CHARACTERISTICS

4 PUMP STORAGE GRINDER INSTALLATION

5 PRESSURE SEWER SYSTEM - PHOENIXVILLE

6 PIPE AND UNIT LAYOUT

7 HYDRAULIC GRADE DIAGRAM

8 PSG AND SYSTEM USE PROFILES

9 DISCHARGE PRESSURE PROFILE OF PSG #3

10 DISCHARGE PRESSURE PROFILE OF PSG #4

11 TEMPERATURE PROFILE OF FLUID FLOWING THROUGH
DATA STATION

12; TEMPERATURE PROFILE OF PSG #3

13 TEMPERATURE PROFILE OF PSG #4
PAGE

37 Thru 42

55
vi
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TABLES

PAGE

1 PERFORMANCE DATA LIST 26

2 COSTS OF HOUSEHOLD RELATED EQUIPMENT FOR 29
THE PHOENIXVILLE PRESSURE SEWER SYSTEM

3 COSTS RELATED TO THE PHOENIXVILLE 30
PRESSURE SEWER MAIN

4 COSTS RELATED TO DATA COLLECTION 31

5 PSG USE CHARACTERISTICS 34

6 PSG OPERATING TIME PER CYCLE 35

7 PSG AVERAGE OPERATING TIME PER DAY 36

8 COMPUTER ANALYSIS 44

9 WASTEWATER CHARACTERIZATION 51, 52

10 UNIT OPERATING COST 53
VII
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SECTION I

CONCLUSIONS
1. The primary conclusion is that the project demonstrated over a
six-month period that a multiple-residence, separate pressure
sewer system can adequately store peak loads of household waste-
water, comminute solids in the wastewater and pump this waste-
water through small-diameter plastic pipe to the existing con-
ventional gravity sewer.

2. The Pump Storage Grinder (PSG), which is the principal component
of the pressure sewer system, easily handled the wastewater loads
imposed on it at the five locations, representing a diverse
sampling of home wastewater usage and location from the sewer
main.

All five PSG units operated satisfactorily including the two
units located at the bottom of the hill which pumped waste to
the main gravity sewer located % mile away and 60 ft. higher
in elevation.

3. The pressure sewer system operated in an anaerobic (septic)
mode with zero oxygen levels.

4. The project demonstrated the ease of installation of the
pressure sewer system, including the PSG. The pressurized
main was installed at a cost of less than $3.00 a linear
foot. Operating costs averaged less than 500/month per living
unit. The initial cost at each household installation, which
included the storage tank, PSG, electrical and mechanical
connections was $2050. This represents an average of approx-
imately $850 per living unit (5 homes, 7 apartments). The
cost of future installations will depend on their size, soil
characteristics, existing systems, cost of labor and materials,
type of equipment and options selected, etc.
-1-
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SECTION II

RECOMMENDATIONS
It is recommended that, as a result of this demonstration, pressure
sewer systems of this type be eonsidered for use as an additional
tool in the formulation of total sewerage system plans. In addition,
it is recommended that additional cost factors for pressure sewers of
this type be developed by expanding the demonstration at Phoenixville,
including evaluation of its effects, if any, on the existing treat-
ment plant.

The following recommendations arose from field experience:

(a) Provide an overflow sensor connected to a visual/
audible alarm in the house to alert the occupants
of PSG or system malfunction.

(b) Grade the vicinity of the storage tank such as to
preclude the entry of surface water and run off into
the tank.
-3-
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SECTION III

INTRODUCTION
Pressure sewer systems are attractive for use in new housing or
industrial complexes where their installation costs can be traded
off against those of conventional sewers, or at existing sites
where septic tanks have become overloaded or operate inefficiently
and require either new tanks or the installation of sewers. Pressure
sewers become even more attractive where hilly terrain makes con-
ventional sewers extremely costly. Several locations in the
Phoenixville area provided examples of the latter two cases.

This project afforded the opportunity to evaluate a pressure sewer
system through actual field operation by connecting several homes to
the terminus of the gravity sewer which was located uphill from
the homes. The basic system design approach was to install a pump
storage grinder unit in a holding tank at each dwelling and con-
nect these to a branch pressure sewer line which tied into the exist-
ing gravity sewer. The farthest site from the gravity main was %
mile away and it was 60 feet below the gravity main.

The General Electric Co. had designed a pump storage grinder (PSG)
and was field testing one engineering prototype when the opportunity
to design a pressure sewer serving multiple residences arose. The
PSG comminutes solids in the wastewater, so that the mixture can be
pumped thru smaller diameter pipe than is possible with conventional
sewage pumps. The pump can deliver moderate flow against relatively
high dynamic pressures (30-40 psig). Because the PSG is installed
in a holding tank, the pump need not deliver the high flow rates
required to keep up with high capacity flows such as toilet flushing.
For this application, the pump selected delivered 15 gpm at zero
head. Other capacities can be utilized depending on the application
and system design.
-5-
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SECTION IV

PROJECT OBJECTIVES
The objectives were to demonstrate over a six-month period, the
feasibility of a multiple-unit, small-diameter pressure sewer system.
It was required to determine if the PSG unit could adequately store
peak loads of wastewater until processed and grind and pump this
wastewater through small—diameter plastic pipes up to a discharge
elevation of 60 feet into a conventional gravity sewer. The
project provided an opportunity to make modifications based on field
requirements and to obtain operating data for future system improvements.
This was to be accomplished by recording a variety of parameters
along a time base and by collecting samples of the wastewater for
analysis and characterization.
-7-
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SECTION V

SYSTEM LOCATION
A group of five residences located along Pennsylvania Highway #113,
on the northern part of the Borough of Phoenixville was chosen as
the test site as shown in Figure 1. A terminus of the gravity sewer
was conveniently located above the first residence. The homes were
spread out over a one-half mile section, with the lowest home being
approximately 60 feet below the gravity sewer terminus. These homes
had been utilizing septic tanks, which provided a suitable backup
system to the proposed pressure sewer.

Other considerations for selecting this site were as follows:

1. The ground was mostly shale and percolation relatively poor.

2. The terrain was hilly, thereby making use of conventional
gravity sewer systems impractical.

3. Sewers were needed immediately. However, the road was scheduled
for filling and widening within the next few years. Any sewers
installed would have been, in some areas, under 60 feet of fill
within a few years, making access and maintenance very difficult.
This would have required new sewers to be installed along with
the road modifications. The problem was solved by using a
pressure sewer since the major equipment cost, the Pump Storage
Grinder (PSG), could remain intact with the house while the
plastic pipes could be replaced very inexpensively along with
the road modifications.

4. A recreational park along the river's edge was planned for this
area. A pressure sewer appeared to be the only feasible means
of getting sewage from the lowlands adjoining the river to the
existing sewer. This addition could be combined with the
existing pressure sewer system.
-9-
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FIQURE 1.
PHDENIMILLE, PA.
-10-
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SECTION VI

GENERAL PRESSURE SEWER COMPONENT DESCRIPTION
A typical pressure sewer system installation is shown in Figure 2.
The existing house wastewater line is diverted from the septic
tank to the Pump Storage Grinder (PSG). The existing septic tank
is utilized as an overflow/emergency tank. The PSG and all piping
are installed below the frost line to prevent freezing during winter
operation. An access area is provided around the unit to allow for
servicing and maintenance. A cover is placed over the access hole.

1. Pump Storage Grinder (PSG)

A sketch and additional details on the Pump Storage Grinder
are contained in Appendix A. The unit operates in the
following manner. A simple, rugged, diaphragm pressure
switch serves as the primary control element. The closure
of this switch energizes a relay which starts the motor,
thereby starting the pump and the grinder. Water and solids
pass through the grinder, where the solids are reduced to
sizes less than % inch, and then into the pump inlet line,
through the pump, through a check valve, and into the dis-
charge pipe. The check valve prevents back-flow from the
pressurized main when the pump is not operating. As the
water level drops while the tank is being emptied, the
pressure switch is opened causing a relay to shut off the
unit.

a. Motor

The motor is manufactured by the General Electric Company,
General Purpose Motor Division, Fort Wayne, Indiana. It
is described as a 1725 RPM, 1 HP, capacitor start, double
shaft, drip-proof motor with built-in thermal overload
protection.

b. Pump

The pump is a MOYNO Model FS-44 and is manufactured by
Robbins and Myers of Springfield, Ohio. This is a pro-
gressing cavity pump' with a hardened, corrosion-
resistant rotor operating in a resilient stator. This
pump has nearly vertical and linear flow characteristics
as approximated in Figure 3 from data provided by the
manufacturer.
-11-
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EXISTING VENT
CO
I
EXISTING GRAVITY
SEWAGE PIPING
.CONTROL BOX

-COVER
.TERRAIN
PRESSURE SEWER
PIPING
DRAINAGE FIELD

EXISTING SEPTIC
TANK/OVERFLOW
OVERFLOW LEVEL SENSOR

ON-OFF LEVEL SENSOR
ISTING GRAVITY SEWER
FIGURE 2. TYPICAL INSTALLATION
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a
s
CO

CO
w
u

a
o
20
10
0
PUMP SPEED:

1725 RPM
10 15

FLOW RATE - GPM

FIGURES.. PUMP CHARACTERISTICS
20
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Grinder
The grinder is very similar in operation to a standard
household garbage disposal. It is directly driven by
the motor at a speed of 1725 RPM. The flywheel is
streamlined, i.e., all contours are smooth and the
impellers (choppers) are reduced in size and made an
integral part of the flywheel. This flywheel design
at the above speed results in a sizeable reduction of
viscous drag and operating power. Twenty-one separate
materials have been successfully tested without stalling
or damaging the grinder. The following general comments
can be made: (1) The materials were handled at widely
different rates. (2) Floating materials enter the
grinder as the liquid surface drops to the level of the
suction bell, (3) dense materials tend to settle to
the bottom of the tank, (4) plastic film, rubber and
cloth are worn away at rates which prevent cumulative
build ups, and (5) mixtures of materials tend to be
ground more readily than single items. Some of the
tested materials include: toilet tissues, paper
diapers, wooden pencils, plastic bags, plastic plates,
and cups, sanitary napkins and elastomeric contra-
ceptives.

Check Valve

The very nature of wastewater,
i.e., its high solids content
including stringy and fibrous
materials, makes the reliable
closure of a check valve
extremely difficult. The
check valve used in the pump
storage grinder unit was
selected with this in mind.
The valve selected was a 3/4
inch bronze swing type, model
number 0630, made by the
Fairbanks Company. Its success-
ful operation is largely
dependent on the following
subtle details: (1) the hinge
point location with respect to the center of gravity of the
swing disc, (2) the mass of the swing disc, (3) a smooth seat,
(4) a self-aligning closure, (5) the eccentric body housing
which provides a pocket for the swing disc when the valve is
fully open, (6) oversize low friction passageways, and (7)
an extra smooth and clean interior configuration.
0630 Sectional
-14-
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e. Relief

A pressure relief valve installed between the pump and
the check valve is intended to prevent damage to the pump
in the event of a system blockage. The relief valve is
set to open between 70 and 75 psig allowing flow back
into the storage tank. In order to minimize the effects
of solids, the valve is mounted on a tee above the normal
flow line. This prevents accumulation of solids in the
area of the relief valve during normal unit operation.

f. Control Box

The control box is a customized electrical junction box
which provides an environmental enclosure for joining the
external power to the motor circuit. It can include the
motor start capacitor, transfer relay used with the
differential pressure switch, manual shut-off switch,
instrumentation connections, etc.
2. Tank
The recommended storage tank is concrete and provides a reservoir
to store peak inflows until they canbe ground and pumped out.
The storage tank can be located so that an existing septic tank
can be used as an overflow during emergency situations, such
as electrical power failures. A tank 30 inches in diameter with
a minimum depth of 36 inches below the overflow line has been
selected as being compatible with a worst case minimum pumping
rate of 8 gallons per minute (gpm) for any one PSG. The tank
mentioned above can store 95 gallons of wastewater before over-
flowing into the septic tank. A 30-inch diameter storage tank
equipped with a 7-inch differential level switch can store approxi-
mately 45 gallons of wastewater before actuation occurs. Upon
actuation, the PSG will pump out approximately 20 gallons of
wastewater before shut off, leaving a 25 gallon residual. The
tank depth can be increased if a larger storage capacity is
desired. The differential between actuation and shut-off can
also be increased, if desired.
3. Pipe
Polyethylene pipe is considered to be ideal for both lateral
and main sewer lines. All fittings and valves would then be
polyethylene. This material produces a tough, flexible pipe
which has excellent chemical resistance to a wide range of
-15-
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3. Pipe (Cont'd)

corrosive fluids such as sodium hydroxide, hydrochloric acid,
sulfuric acid, etc. Polyethylene is flexible enough to be
plowed in. "Plowing-in" refers to the process that combines
trenching, feeding of coiled tubing or cable from a spool into
a trench and backfilling all in the same operation. This
process makes it possible to rapidly bury long lengths of pipe
in a trench.

Polyethylene, schedule 40, two-inch pipe has a design pressure
rating of 125 psig. The pipe may be cleaned in the event of
blockage by flushing with chemicals, with high pressure water or
by the introduction of a "rotating snake". A suitable alternate
pipe is polyvinylchloride (PVC). This has the same desirable
characteristics as polyethylene except it is not as flexible.
PVC is not flexible enough to be coiled, therefore, it is not
compatible with the "plowing-in" operation. The choice of pipe
material depends on the terrain, distance and availability of
'' plowing-in'' equipment.
-16-
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SECTION VII

PHOENIXVILLE SYSTEM DESCRIPTION
Five residences were involved in the project. A storage tank with
a Pump Storage Grinder installed in it, was interposed in each
existing building sewer line at a convenient location between the
residence and the septic tank. The existing septic tanks were used
as emergency storage tanks in the event of overflows from the PSG
tanks. The PSG outlets were fed into the pressure main, more than
one half mile in.length with a 70 -foot elevation differential
(the lowest point in the system is 10 feet below the last home),
which discharged to the existing gravity sewer. A bypass line was
routed through a data collection station. Data cable was installed
along with the pressure piping and connected each PSG and sensor
to recording equipment in the central data station. The PSG units
and all piping were installed below the frost line at a depth of 30
inches. The installation required approximately 2800 feet of 2-inch
and approximately 700 feet of 1%-inch PVC pipe, 5 pump storage grind-
er units, and 5 storage tanks. Also included were electrical and
mechanical tie-ins to existing facilities. Approximately 3000 feet
of 52 pair data cable and approximately 500 feet of 13-pair data
cable were also installed.

The electrical work included supplying and installing a 20 amp,
110 v. ac "slow blow" circuit breaker in the residences as well as
a suitable 20 amp, llOv. ac power line from the circuit breaker to
the pump storate grinder unit. The power cable was run underground.
Figures 4, 5 and 6 show the PSG assembly as installed, the system
layout (elevation) and the pipe and pump layout, respectively. The
demonstration period extended for 6 months after system start-up.
The data station was checked periodically by Phoenixville personnel.
Data was collected by General Electric RESD personnel on a weekly
basis and reviewed to determine any system changes or trends which
might indicate future problems. The PSG units were also inspected
on a weekly basis by General Electric RESD personnel. Until system
safety was assured, these inspections included a check for objection-
able gas formation. Inspection procedures are outlined in Appendix
B.
-17-
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GROUND LEVEL
SEWAGE FROM HOUSE
CONCRETE BASE
REINFORCED CONCRETE PIPE
INLET LINE
PRESSURE LATERAL
POWER LINE
VERTED CONCRETE COVER
BALL VALVE
3/4" TO 1-1/2" REDUCER
COUPLING, GE SUPPLIED
CHECK VALVE, GE SUPPLIED
PLUG, GE SUPPLIED
CONTROL BOX, GE SUPPLIED
GROUT
SUPPORT, GE SUPPLIED
HANGER, GE SUPPLIED
BRACKET, GE SUPPLIED
ALARM SENSOR, GE SUPPLIED
RELIEF VALVE, GE SUPPLIED
LEVEL SENSOR, GE SUPPLIED
OVERFLOW LINE
PUMP GRINDER, GE SUPPLIED
DATA CABLE
FIGURE 4. PUMP STORAGE GRINDER INSTALLATION

-18-
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PROFILE
peer
300O
MAMHOLS
FIGURE 5. PRESSURE SEWER SYSTEM, - PHOENIXVILLE
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NS
O
CLEAN OUT
-e-
PSG
# 5
HOME # 4
PSG #2 PSG # 1
HOME # 1
PSG # 3
2751
HOME # 3
HOME # 2
STATION # 2
BALL
VALVES
MONITOR
HOUSE
MAN
HOLE
H
-ROUTE 113
STATION
# 1 UNDER ROAD IN
6" A. C. PIPE
296'
PSG # 4
LEGEND

PVC PIPING

HOME SEWER OUTLET
HOME # 4A
FIGURE 6 . PIPE AND PUMP LAYOUT
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The energy or hydraulic grade diagram for the system is shown in
Figure 7. This diagram was developed by assuming that minimum
system pressure would occur when only unit #4 was operating. From
this "minimum" pressure line and the pump Characteristic curve, (Figure
3), the actual flow from each storage grinder was calculated. A new
"maximum" pressure line was then established based on all units
operating simultaneously. A final calculation, utilizing this "max-
imum" pressure line, verified that the system would operate between
the pressure limits shown in Figure 7.

Assuming that a maximum pressure of 60 psig can be developed by each
unit, an "available" pressure line was plotted. Since the "available"
pressure line is in every case above the maximum operating pressure,
the design is shown to be practical. The minimum system velocity is
1.2 feet per second (fps) and occurs when PSG #4 is operating alone.
This is compatible with the desired minimum scouring velocity of 1.0
fps. With units #4 & #5 operating together the velocity would be 2.2
A computer program was developed to further describe and analyze the
Phoenixville pressure sewer system installation. The program
(Phoenix) is a deskside digital computer program which calculates
flows, velocities, friction head and pressures based on the provided
input data. The input data required are the number of stations,
pipe diameter, pipe length, and static head between stations. A
station is defined as the junction of the road main and the laterals
from the PSG units. Input data also required are the pipe diameter,
pipe length and static head of the laterals. This also requires
an initial pressure at Station 1 and the interface pressure with
the connecting system. If the connecting system is a gravity sewer
the interface pressure will nominally be zero.

The Program takes the input pressure at Station 1 and calculates the
pump pressure and flow.

Summing pump flow at Station 1 the program calculates the friction
head in the road main to Station 2. The program then calculates
the pressure at Station 2. The process is repeated at each station
until the interface or discharge pressure is calculated. If the
discharge pressure is greater than 0.05 psi the program calculates
a new input pressure and repeats the previous calculations. Several
iterations are, generally required for a solution.
-21-
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NJ
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138 FT./boPS/G AVAIL.
FROM PS©, MINUS 1.5"
LATERAL PIPE A/V£>
F/TT/NG LO5S.
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GRADE: UME, a
ALL MAI ITS
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ROAD PROFILE

(Pressure sewer -2.5
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EEET (ALONG ROAD )

FIGURE 7 . HYDRAULIC GRADE DIAGRAM
-------
The equations used in the program are the pressure-flow characteristics
of the pump and the friction head of the pipe. The equation of the
progressive cavity pump characteristics is:

Qfo - 15.0 - 0.115 P0
Where: Q0 = Pump output flow, gpm
Po = Pump output pressure, psig

The head loss due to fluid flow in the pipe is calculated using
the empirical Hazen-Williams formula:
1.852
Where: Hf = Friction head per foot, ft,

V = Fluid velocity, ft./sec.

D = Pipe diameter, ft.

C = Coefficient representing roughness
pipe interior surface (C=150 for
PVC pipe).

The characteristics of the equipment used at Pltoeftixville are listed
below:

1. Pump Storage Grinder

The PSG units were of the design configuration shown in Appendix
A . This particular design required that the uppermost part of
the PSG, the electrical cable exit and potting, be above the
overflow line. This requirement was necessary because the
units were not completely submersible. Units #'3 and 4 were
piped to allow for the incorporation of a temperature sensor "and
pressure transducer. The control box was mounted on brackets
attached to the storage tank. Electrical power was supplied to
the box from the home using #12-gage wire and connected with
twist lock plugs, as shown in Figure 4. The control features
included an on/off switch and the necessary circuitry to operate
the unit and level sensing system. Since the overflow alarm
sensor was for data only, it was not required to be routed
through the control box. Electrical power was llOv. ac, single
phase, 60 Hz.
-23-
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1. Pump Storage Grinder (Cont'd)

The level sensing system used on the first pump storage
grinders field tested by GE-RESD relied on a pressure
differential switch that sensed the pressure buildup of
an air column trapped in a dip tube. This method of
level control was plagued with two problems: one, air
leakage in the dip tube, and two, dip tube blockage caused
by wastewater solids. The five pump, storage grinders tested
at Phoenixville, used a submersible pressure differential switch
for level control. The switch consists of a snap action,
double throw, micro switch that is activated by a rubber
diaphragm. At the time of the demonstration, the submersible
differential switch was available with only a few different
operating pressure differential settings. The switch
selected has a differential of 7 inches between actuation, and
cut-off level. When installed in a 30-inch diameter tank,
the level sensing system would actuate the PSG when approxi-
mately 45 gallons of wastewater had accumulated and deactivate
the unit after pumping approximately 20 gallons, leaving a
residual of 25 gallons in the storage tank.

The choice of operating range for the switch, is somewhat
arbritary, although dependent on other system parameters
such as anticipated wastewater influx, tank size, operating
cycles or system programming and pump capacity.

2. Piping

Polyvinylchloride (PVC) pipe was used at Phoenixville because
of its availability. The PVC was schedule SDR-26; it was
capable of withstanding hydrostatic working pressures of
160 psig at 73°F, and conformed to requirements set forth
by ASTM-D 2241. All 2-inch pipe had an inside diameter of
2.2 inches. All 1% inch pipe had an inside diameter of 1.75
inches. All fittings were PVC schedule 40. All pipe was
installed at a depth of 30 inches. The trench did not exceed
4 inches in width except where necessitated by rock removal.
Loose bed rock was removed by a backhoe. All of the PVC
pipe was encased in 4 inch asbestos cement pipe where it
crossed under public or private roads. The PVC pipe was
handled and installed in strict accordance with the manu-
facturer's instructions. Care was taken during installation
to prevent entry of foreign material which would have
hindered flow through the pipe. The pressure system was leak-
checked at a pressure of 100 psig at the completion of construc-
tion. As shown in Figure 7, the maximum system operating
pressure analytically should have been below 60 psig.
-24-
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2. Piping (Cont'd)

Access to the pipe lines was available through fittings at
each pump storage grinder unit and through the clean-out
box at the "bottom" of the system, illustrated on the right
hand side of Figure 6.

3. PSG Storage Tank

The storage tanks were constructed from 8-foot sections of
30-inch inside diameter reinforced concrete sewer pipe. The
pipe met the requirements set forth by ASTM and the Pennsylvania
Department of Transportation for C76, Class 3 pipe. The 8-foot
section of pipe was installed so that the top was level with the
ground. The base of the tank was a minimum of 6 inches of
poured concrete. A light duty cover was supplied by the con-
struction contractor and was capable of withstanding the load
of a home garden tractor or equivalent. The cover was 36 inches
in diameter. The tank intercepted the existing home sewer
line prior to its entry into the septic tank. The overflow
line was a minimum of 36 inches from the bottom of the tank.
The inlet line was higher than the overflow point. The actual
tank depth was determined by the above requirements, as well
as the depth of the existing home sewer line.

4. Data System

The data system supplied operating and chemical data. Electrical
power (110 v. ac, single phase, 60 Hz) was available in the data
station to operate the data system. A small electric heater
was also used. The data system operated for the total 6-month
demonstration period. All sensors were installed so that they
were readily accessible for maintenance purposes, and the
system contained calibration capabilities. The data station
was approximately 8' x 10' x 61 high, was locked, and was
sturdy enough to prevent vandalism. Data was transmitted from
the individual sensors to the data station via the data cable.

The operating data included on time, overflow time and real
time for each unit, and temperature and pressure readings at
units # 3, # 4 and the data station, as shown in Table 1.
The operating real times were determined from the recorder
chart speed. Temperature was monitored with a thermistor probe
attached to the outside of a section of pipe. This section
of pipe was over-wrapped with insulation. The probe was located
a minimum of 3 inches from either end of the insulation.
-25-
-------
TABLE 1

PERFORMANCE DATA LIST
MEASUREMENT

On and overflow time

Total cycles

Operating pressure

Temperature
FREQUENCY
1/48 sec.

as occur
1/44 sec
LOCATIONS
PSG #'s

PSG #«s
PSG #' s
1-5

1-5
3 & 4
TYPE OF SENSOR
Relay contacts
level switch
contacts
Counter
Transducer
1/44 sec
Data Station

PSG #• s. 3 & 4
Data Station
Thermistor
-------
4. Data System (Cont'd)

The pressure transducer was used in conjunction with a small
diameter, silicone grease filled, interface tube between the
transducer and the wastewater. All sensors which were installed
in the storage tanks were capable of operating in high humidity
environments at outdoor ambient temperatures. The recorder was
the multiple (24) point type and was capable of running one week
without the need to refill the chart paper. The monitor panel
contained lights to indicate an "on" or an "overflow" condition
for each unit. The data cable was a standard type used by
utility companies for underground installation.

The wastewater characterization data was obtained from waste-
water grab samples which were collected and analysed during
3 sample periods. The wastewater samples where obtained via
a hand valve in the main pressure line in the data station.
Composites were prepared by taking several grab samples over a
period of time until a liter of solution was obtained. Each
grab sample was approximately 200-300 ml. The following
analyses were performed:
Alkalinity
Ammonia Nitrogen
Bacterial Count (Coliform)
Biochemical Oxygen Demand (BOD)
Calcium
Chemical Oxygen Demand
Chloride
Conductivity
Detergents
Dissolved Oxygen
Magnes ium
Nitrate
Oxidation-Reduction Potential (ORP)
pH
Phosphate
Settleable Solids
Sulfate
Total Suspended Solids (TSS)

The oxidation reduction potential (ORP) was to be obtained by
continuously recording the output of an ORP sensor located in
the data station. However, an unprecedented long strike against
the vendor (Leeds & Northrup) precluded us from obtaining this
data continuously. Instead, the oxidation-reduction potential
-27-
-------
4. Data System (Cont'd)

of the grab samples was measured using a portable,
battery-powered ORP meter. The magnesium and'calcium
analyses were performed by the atomic absorption method.
All other analyses were performed according to Standard
Methods for Examination of Water and Wastewater, 13th
Edition.

5. System Costs

Table 2 lists the material and installation costs of household
related equipment, such as the PSG and its storage tank, used
in the Phoenixville pressure sewer system. The PSG unit cost
of $900.00 was based on prototype models. The total costs
listed for item 2 through 6 were actual costs charged to the
project by the contractor. The cost per unit, per foot or per
installation was calculated by dividing the total cost by the
actual quantity of material used in the system.

Table 3 lists material and installation costs related to the
Phoenixville pressure sewer main. The total cost listed for
the various items were costs charged to the project by the
contractor. Once again, as in Table 2, the unit cost was
calculated by dividing the total cost by the actual quantity
in the system.

Table 4 lists the costs related to the data collection. It
should be noted that a typical pressure sewer system would
not require a data collection system.

It is difficult to provide meaningful cost estimates for
future installations because they depend on such factors as
the number of homes, total distance and piping runs, soil
of conditions, type of equipment available, pipe sizes, new
construction or converting present installations,
whether or not any existing facilities are available.
.28-
-------
TABLE 2

COST OF HOUSEHOLD RELATED EQUIPMENT FOR THE PHOENIXVILLE PROGRAM
ITEM
PUMP STORAGE GRINDER (PSG)
AND CONTROLLER
UNIT COST
$/UNIT
900.00 per
UNIT
STORAGE TANK; EXCAVATE,
SUPPLY AND INSTALL 30" DIA.
8f LONG SEWER PIPE SECTION;
POUR CONCRETE BOTTOM, SUPPLY
COVER; TIE-IN HOME SEWER IN-
PUT LINE, OVERFLOW LINE,
PRESSURE.LATERAL; INSTALL
PSG AND RESTORE AREA.

PRESSURE LATERALS; SUPPLY
1%" PVC PIPE - SCHEDULE
SDR-26, EXCAVATE, INSTALL
AND RESTORE AREA.

HOME CIRCUIT BREAKER;
SUPPLY AND INSTALL

POWER CABLE; SUPPLY AND
INSTALL SUITABLE UNDER-
GROUND ELECTRICAL CABLE
FROM HOME CIRCUIT BREAKER
TO PSG STORAGE TANK.

MISCELLANEOUS PVC PIPE
FITTINGS USED IN PRESSURE
LATERAL TIE-IN TO PSG.
600.00 per
INSTALLATION
2.50 per
LINEAR FOOT
60.00 per
INSTALLATION
3.00 per
LINEAR FOOT

20.00 per
INSTALLATION
QUANTITY

5 units

1 spare
TOTAL
COST
5,400.00
5 3,000.00
INSTALLATIONS
700 FEET
TOTAL
INSTALLATIONS
1,750.00
300.00
200 FEET
TOTAL
INSTALLATIONS
600.00
100.00
(APPROX)
TOTAL $11,150.00

AVERAGE COST PER RESIDENCE, EXCLUDING COST OF SPARE UNIT $ 2,050.00

AVERAGE COST PER DWELLING UNIT (12) (LESS SPARE) $ 854.17
-29-
-------
TABLE 3

COSTS RELATED TO PHOENIXVILLE PRESSURE SEWER MAIN
ITEM
PRESSURE MAIN; SUPPLY 2"
PVC SCHEDULE SDR-26 PIPE,
EXCAVATE, INSTALL, TIE-IN
TO PRESSURE LATERALS AND
RESTORE AREA.

ROCK REMOVAL ON A PER
CUBIC YARD BASIS

RESTORATION OF PAVED HIGH-
WAYS AND DRIVES ON A PER
CUBIC YARD BASIS.

RESTORATION OR UNPAVED
DRIVES ON A PER CUBIC
YARD BASIS.
UNIT COST
$/UNIT
QUANTITY
2.00 per
LINEAR FOOT

20.00 per
CUBIC YARD

15.00 per
CUBIC YARD
2.00 per
CUBIC YARD
PROTECT ALL PRESSURE SEWER
PIPE WHICH RUNS UNDER HIGH-
WAYS OR DRIVES BY ENCASING
IT IN ASBESTOS CEMENT PIPE,
4-INCH DIAMETER; ON A PER 3.00 per
LINEAR FOOT BASIS. LINEAR FOOT
AIR RELIEF VALVE: SUPPLY
AND INSTALL IN PRESSURE
MAIN; PROTECT IN BUFFALO
BOX (6"), RISERS (30"
HIGH X 4" DIAMETER)

PROVIDE CLEANOUT; SUPPLY
SHUT-OFF VALVE, PROTECT IN
BUFFALO BOX (6"), RISERS
(30" HIGH X 4" DIAMETER)
350.00 per
VALVE
350.00 per
INSTALLATION
TOTAL
COST
_$
2800 FEET
60 CUBIC
YARDS

10 CUBIC
YARDS
50 CUBIC
YARDS
5,600.00

1,200.00

150.00

100.00
40 FEET
1 REQUIRED
120.00
350.00
1 REQUIRED
TOTAL

AVERAGE COST PER FOOT OF PHOENIXVILLE SEWER MAIN $2.82
350.00
$7,870.00
-30-
-------
TABLE 4

COSTS RELATED TO DATA COLLECTION

TOTAL
ITEM QUANTITY COST
_J

DATA STATION STRUCTURE 1 1,100.00

DATA CABLE - 52 PAIR: ON A PER LINEAR
FOOT BASIS : SUPPLY AND TIE-IN. 3000 FEET 5,500.00

DATA CABLE - 13 PAIR; ON A PER LINEAR
FOOT BASIS, SUPPLY AND TIE-IN. 500 FEET 500.00

CONNECT PRESSURE SEWER SYSTEM TO DATA 1 820.00
STATION: SUPPLY AND INSTALL VALVES,
PROTECT IN BUFFALO BOXES (6"), RISERS
(30" HIGH X 4" DIAMETER)

INSTRUMENTATION (MISC) - 1,400.00

TOTAL COST OF PHOENIXVILLE DATA COLLECTION SYSTEM $9,320.00
-31-
-------
SECTION VIII

DEMONSTRATION RESULTS

The following paragraphs present the data obtained from the demon-
stration, including operating cost. Reference to Appendix B will
identify the typical check-off list used at the site for data
collection.

1. PSG Use Characteristics

The total operating time and cycles for each unit as well
as the type of residence serviced is given in Table 5.
Table 6 shows the average operating time per cycle for
each unit by month. The average operating time per cycle
is related to the operating differential of the level
switch and to the pump output. The operating time per
cycle of units #1, #2, #3, and #5 was lower than that
expected. Investigation revealed that the level switch
used on these units had a 4-inch differential instead
of the 7-inch differential. Unit #4 did have a 7-inch
differential level switch. Table 7 shows the average
PSG operating time per day by month. Typical weekly
use profiles were plotted for each unit and the system
in Figures 8 (a) through 8 (f). Unit operating time
in minutes per real time hour was plotted for a week.
The intent of these profiles was to identify peak
activity periods during the day and week. The use
profile data was obtained by reducing the output of a con-
tinuous strip chart recorder, operating at a speed of 8
inches per hour, that was recording unit operating time.
The use profile shown are representative of the beginning,
middle and end of the demonstration period.

2. Flow and Pressure Data

The flow and pressure characteristics of the system were
initially described by the computer program. The computer
program calculated pressure and flow characteristics at each
of the five PSG locations and three station locations. The
results of several computer runs are shown in Table 8. It
can be seen from the data that PSG's #1, #2, and #3, which
are at the higher elevation, operate at relatively low pres-
sures, i.e., less that 12 psig. Units #4 and #5 which are
at the lower elevation operate at roughly 35 psig when
operating alone. The discharge pressure of each pump rises
-33-
-------
-p*
TABLE 5

PSG USE CHARACTERISTICS
PUMP STORAGE
GRINDER NO.
#1
n
#3
#4
#5
TOTAL
HOURS
50.9
160.0
102.8
182.4
123.4
TOTAL
CYCLES
4526
15306
6792
5016
6946
TOTAL DAYS
IN SERVICE
195
195
190
189
189
TYPE OF RESIDENCE 'SERVICED BY PSG
SINGLE HOME
5 APARTMENT UNITS (2 houses)
SINGLE HOME
4 APARTMENT UNITS + SINGLE HOME
3 APARTMENT UNITS
NO.
PEOPLE
2
11
3
10
6
-------
TABLE 6

PSG OPERATING TIME PER CYCLE*

PUMP STORAGE GRINDER
MONTH
FEBRUARY
MARCH
APRIL
MAY
JUNE
JULY
AUGUST
#1
0.66
0.66
0.66
0.69
0.67
0.71
0.67
#2
0.70
0.58
0.57
0.55
0.68
0.66
0.73
#3
0.87
0.87
1.0
0.91
0.92
0;96
0.93
#4
2.11
2.02
2.03
1.83
2.29
1.97
«• «•«••
#5
1.05
1.22
1.05
1.09
1.06
1.04
0.91
*A11 values are expressed in minutes/cycle
-35-
-------
TABLE 7

PSG AVERAGE OPERATING TIME PER DAY*
MONTH
FEBRUARY
MARCH
APRIL
MAY
JUNE
JULY
ATTHTTST
#1
26.8
23.8
15.3
11.1
12.3
8.15
14..9
#2
91.5
67.5
50.6
39.4
39.0
23.2
A^.fi
#3
64.5
38.0
26.9
39.8
26.1
4.2
LQ S
#4
34.0
38.6
59.5
79.3
74.6
68.2

#5
19.0
39.3
24.5
33.2
36.5
51 = 4
<^ LL
*A11 values expressed in minutes/day
-36-
-------
co
^i
i
SA
Jtl TTO17 T>T>(-ITJTT T?
-------
I
co
oo
FIGURE 8B. PSG #2 USE PROFILE
-------
I
CO
FIGURE 8C- PSG #3bUSE PROFILE
-------
FIGURE 8D . PSG #4 USE PROFILE
-------
FIGURE 8E. PSG #5 USE PROFILE
-------
•p-
N5
FIGURE 8F. USE PROFILE
-------
TABLE 8

COMPUTER ANALYSIS OF SYSTEM
PSG UNITS PUMP
OPERATING NUMBER
1 1
2 2
3 3
4 4
5 5
1 & 2 1
2
4 fit 5 4
5
All units 1
2
3
4
5
PUMPS PUMP STATION STATION
PRESSURE 'FLOW NUMBER PRESSURE
psig gpm # psig
10.3
10.6
11.7
34.9
35.1
23.4
23.6
43.7
43.9
20.3
20.5
23.1
52.3
52.5
13.8
13.8
13.7
11.1
11.1
12.4
12.4
10.1
10.1
12.7
12.7
12.4
9.1
9.1
3
3
2
1
1
3
3
1
1
3
3
2
1
1
3.5
3.4
6.0
31.0
31.0
19.1
19.1
40.4
40.4
14.5
14.5
18.4
49.7
49.7
STATION
FLOW
gpm
13.8
13.8
13.7
11.1
11.1
24.7
24.7
20.2
20.2
56.1
56.1
30.7
18.3
18.3
FRICTION
HEAD
feet
2.1
2.0
2.9
10.7
10.6
10.7
10.7
32.4
32.4
27.5
27.5
4.1
21.9
21.9
VELOCITY PIPE
DIAMETER
ft/ sec CINCHES
1.5
1.5
1.5
1.2
1.2
4.5
4.5
2.2
2.2
6.1
6.1
3.3
2.0
2.0
1.94
1.94
1.94
1.94
1.94
1.50
1.50
1.94
1.94
1.94
1.94
1.94
1.94
1.94
-------
2. Flow and Pressure Data (Cont'd)

substantially when all units are running simultaneously,
as illustrated by the data in Table 8.

The maximum pressure calculated by the computer is 52.5
psig which is the discharge pressure of PSG #5 when all
units are operating. The maximum flow in the system,
56.1 gpm, is found at station #3 when all units are
operating. The minimum flow in the system is 9.1 gpm.
This flow represents the discharge flow rate of units
4 and 5 when all other units are operating as well. It
should be noted that in all cases the fluid velocity is
larger than the necessary 1.0 ft /sec scouring velocity.
It should be noted that the measured discharge pressures
of units #3 and #4, at the beginning of the demonstration
were very close to that calculated by the computer program.
This would indicate that the program described the Phoenix-
ville system quite well.

As part of the data collection, pressure was monitored
throughout the entire project at the data collection
station, PSG #3 and PSG #4. Pressure transducers were
installed in the exit piping of PSG #3 and PSG #4 and
in the two-inch PVC piping which ran through the data
collection station. The discharge pressure profiles of
units #3 and #4, when they are operating alone, are shown
in Figures 9 and 10. The slight reduction of discharge
pressure shown in Figure 9 could be the result of a worn
pump stator or possibly a calibration drift of the
pressure transducers used. The increase in discharge
pressure of PSG #4 shown in Figure 10 is too large to
be caused by calibration drift. This trend could possibly
be an indicator of a gradual reduction of cross-sectional
flow area. At this time, however, a conclusive statement
cannot be made. The piping system was provided with a clean-
out if flushing became necessary.

It was not possible to correlate wastewater efflux with water
inlet to each home because the borough does not individ-
ually meter water consumption.
-------
FIGURE 9. DISCHARGE PRESSURE-PROFILE OF PSG #3
-------
FIGURE 10. DISCHARGE PRESSURE PROFILE OF PSG #4
-------
3. Wastewater Temperature Data

The temperature of the wastewater in the pressure sewer
system was monitored at the data collection station, PSG
#3 and PSG #4. In all three locations a thermistor probe
was used. The temperature sensors were calibrated at GE-
RESD and also at the test site to insure an accurate
calibration. In the data collection station a temperature
sensor was taped to the 2-inch PVC pipe with a special
temperature insulating tape. At units #3 and #4 the temp-
erature sensors were located on the brass pipe fitting
nearest the PSG exiti, The temperature insulating tape
was used for attachment purposes as well as for insulation.
Figures 11, 12 and 13 show the temperature profiles during
the six^month demonstration period for these three locations.

4. Wastewater Characterization
The wastewater flowing through the pressure sewer was
characterized by testing various grab samples taken
from the sample port in the data collection station.
The results of these tests are shown in Table 9. In the
interpretation of this data it should be emphasized that
sappling was limited both in number of samples and time
of day when taken. Also, the wastewater is domestic
waste and contains no industrial materials or significant
storm water run-off as does municipal wastewater* Some
surface water did enter the tanks because they were set
level with the ground and the covers were not water tight.

The data presented shows the system to be operating in an
anaerobic -(septic) mode. This condition probably resulted
from an excessive holding time, that is, the time elapsed
from the moment the wastewater was introduced to the pressure
sewer system to the time it was discharged into the gravity
sewer line. There were no gases or odors noticed around
the PSG installations.

5. Unit Operating Cost

The unit operating cost per day, month, and year is
given in Table 10. The typical rate for the area, $0.03
per kilowatt-hour was used in the calculations. Units
#1, #2, and #3 had an average current draw of 12.5 amps.
Units #4 and #5 which operate at a high discharge pressure
had an average current draw of 14.0 amps.
-47-
-------
-p-
00
FIGURE 11. TEMPERATURE PROFILE OF FLUID FLOWING THROUGH DATA STATION
-------
FIGURE 12, TEMPERATURE PROFILE OF PSG #3
-------
I
-------
I
Cn
TABLE 9

WASTEWATER CHARACTERIZATION
DATE
PARAMETER SAMPLE TIME
pH
DISSOLVED OXYGEN (mg/1)
ORP (mv)

BOD (mg/1)
COD (mg/1)
SUSPENDED SOLIDS (mg/1)
SETTLEABLE SOLIDS (mg/1)
COLIFORMS (No/ 100 ml)
MAGNESIUM (mg/1)
CONDUCTIVITY (mhos /cm)
DETERGENTS (MB AS)
6/8/71
12:00 noon
1:00 p.m.
7.2
-
-

104
311
108
20
2.4X104
6.3
500
2
6/17/71
9:00 a.m.
11:00 a.m.
8.3
0
_

198
524
224
102
1.7X104
6.6
850
4.5
6/28/71 6/29/71
12:00 noon 9:00 a.m.
9:15 a.m.
8.3
0 0
-200 -230 9:00
-160 9:15

-
_
514
-
-
-
-
_
7/2/71 7/6/71
9:30 a.m. 9:30 a.
10:00 a.
7.9
0 0
-80 +60 9:
+30 9:
-10 9:
-20 10:
135
343
146
80
4.3X104
110
920
2.9
m.
m.

30
40
50
00

-------
TABLE 9 (Cont.)

DATE 6/8/71 6/17/71 6/28/71 6/29/71 7/2/71 7/6/71
PARAMETER SAMPLE TIME 12:00 noon 9:00 a.m. 12:00 noon 9:00 a.m. 9:30 a.m. 9:30 a.m.
1:00 p.m. 11:00 a.m. 9:15 a.m. 10:00 a.m.

1
Ul
NJ
1

AMMONIA NITROGEN (mg/1)
as NH3-N
TOTAL PHOSPHATE (mg/1)
as PO4~P
ALKALINITY (mg/1)
as Ca03

SULFATE (mg/1)
NITRATE (mg/1)
as N03-N
CHLpRIDE ftng/l)
CALCIUM (mg/1)
36.3

5.8

188

72
2

42
37
66.5

19 -

315

78
2

68
28
74.1

9.6

360

100
2

.-92
20.6
-------
l/l
TABLE 10

UNIT AVERAGE OPERATING TIME AND COSTS
PSG
1 -
2 -
3 -
4 -
5 -
NO.
SINGLE HOME
2 PERSONS
2 HOMES (5 APART,'
11 PERSONS
SINGLE HOME
3 PERSONS
4 APART. + 1 HOME
10 PERSONS
3 APARTMENTS
HRS/DAY
.27
>
.87
.55
.98
.57
$/DAY
.012
.039
.025
.05
.03
HRS/MO.
8.1
26.0
16.5
29.4
17.1
$/MO.
.36
1.20
.75
1.60
.90
HRS/YR.
98
318
200
358
208
$/YR.
4.40
14.30
9.10
19.00
11.00
6 PERSONS
TOTAL
3.24
.16
97.1
4.81
1182
57.80
-------
6. Problems Encountered

During the check-out phase of the project, the holding
tank for PSG #5 was filled with water when a valve
coupling was inadvertently removed allowing the system
to drain into the tank. Also during this phase, unit #3
was found to have a large chunk of concrete firmly
wedged in the inlet hopper (throat). It is unclear
how this occurred. The concrete could not have been
sucked in since it was too heavy and too tightly wedged
into the hopper. As a result of this, the two cutter blade
retaining screws were sheared. These were replaced and
the unit was returned to service.

On March 9, 1971, the control box in tank #3 was replaced
with the spare control because of unpredictable circuit
breaker operation. Investigations at GE-RESD found no
problem with the rest of the control box equipment which
performed properly with a new circuit breaker.

On April 1, 1971, the pump grinder in tank #4 became
inoperative and was replaced with the spare pump grinder.
The inoperative unit was rfound to be filled with water
which caused the motor to electrically short. The water
had entered the unit through a fracture in the stainless
steel flexible outlet line. The fracture was in the
line near the pump fitting end and was attributed to a
defective part.

Some slight difficulty was experienced with the data
station and air relief valve pipe. On March 9, 1971,
it was determined that the power line to'the'data station
and the air relief valve pipe needed repairs. The
power line voltage was low and the relief valve pipe
had been damaged, probably during routine snow removal
by heavy equipment. The complete pressure sewer system
was shut down during March 9 and 10 while repairs were
quickly completed. Later, on April 12, 1971, the
recorder print out drive line was found broken. The line
was repaired, and the recorder was back in operation
on April 16. This problem was found again on May 18,
1971 and repairs were completed on May 19.
-54-
-------
6. Problems Encountered (Cont'd)

On July 29, the pump grinder in tank #4 became inoperative,
The unit was brought back to GE-RESD for analysis. The
failure analysis showed that the flywheel cutter assembly
had backed off of the motor shaft slightly, thus reducing
the necessary compression on the rotary shaft seal.
Water had entered the unit via the shaft seal and elec-
trically-shorted the motor. The unit was repaired and
placed back into operation August 26.

On Oct. 21, 1971, -during the final routine check of the
system, units #3, #4, and #5 were found inoperative.
Investigation revealed that there was no power at units
#4 and *5 due to faulty cable splices installed by the
contractor. Unit #3 had a ruptured flexible line.
This deficiency had been previously experienced, and
corrective action was instituted by changing to a
rubber hose. All three units were updated by incor-
porating the flywheel lockwire, and replacing the
steel flexible hose with rubber hose.
-55-
-------
SECTION IX

ACKNOWLEDGEMENTS
Mr. John Kane, former manager of the Borough of Phoenixville,
Pennsylvania, played a vital role in getting the project
approved and underway. His support of the project and assistance
during the construction phase and system start up is acknowledged
with sincere thanks. The support of Mr. Stephen Ross, acting
manager of the Borough of Phoenixville, Pennsylvania, during the
demonstration period is acknowledged with sincere thanks.

The Re-Entry and Environmental Systems Division of the General
Electric Company (RESD), Philadelphia, Pennsylavania, is credited
with the design of the Phoenixville Pressure Sewer System and the
implementation thereof, including the design and manufacture of the
Pump Storage Grinder units and the design of the data monitoring
system.

The engineering effort was conducted under the-management of Mr.
Gilbert E. DiSalle, manager of Actuation Equipment Engineering,
RESD, and Mr. James F. Hall, Jr. former manager of Machine Design
Engineering, RESD., and Mr. Daniel 0. Ramos, Project Engineer,
RESD.

Mr. George Mekosh, Jr., design engineer, RESD, was responsible
for providing engineering support during system installation,
monitoring the demonstration and writing this report.

The installation of the pressure sewer system was performed by the
Altemose Construction Company, Norristown, Pennsylvania, under the
direct supervision of Mr. Lester Horvath.

The support of the project by the Environmental Pfote&tion Agency
and the help provided by Mr. James F. Kreissl, Project Officer,
is acknowledged with sincere thanks.
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SECTION X

APPENDICES

PAGE

A. P.S.G. OPERATION AND INSTALLATION MANUAL 61

FIGURE A-l PSG INSTALLATION 66

B. CHECK-OFF LIST PROCEDURE FOR PHOENIXVILLE 69
PRESSURE SEWER INSPECTION
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APPENDIX A
PUMP STORAGE GRINDER
OPERATION AND INSTALLATION
MANUAL
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OPERATION
The basic function of the Pump Grinder is to mascerate and then
transport wastewater,under pressure. The primary control element
of the Pump Grinder, as shown in Figure A-l, is a simple, rugged
diaphragm switch. When the water level in the storage tank rises
to a preset level, the diaphram switch closes and activates a
set of relays. These relays which are located inside the
control box start the motor which drives the pump and the grinder.
During operation, water and solids pass through the grinder and
the solids are reduced in size to less than 1/4 inch. After
the mascerated wastewater leaves the grinder it enters the pump
inlet line, passes through the pump, through a check valve, and
into the discharge pipe. The check valve prevents back-flow.
As the water level in the storage tank drops to a given level,
the diaphragm switch opens and shuts off the motor. The pump
grinder is also equipped with an overflow alert switch. This
switch will send out a signal when the system is in an over-
flow condition.
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PUMP GRINDER SPECIFICATION SHEET

1. Funct ion;

Shred and pump wastewater through small diameter plastic
pipes. Store peak loads until processed.

2. Grinder Performance;

Materials are ground to less than 1/4 inch in size before
entering the small diameter piping. Heavy materials,
such as metals, settle to the bottom of the tank for
periodic removal. All materials can be handled (paper,
wood, cloth, plastic, rubber, etc.).

3. Pump Performance;

8 gpm @ 60 psig

15 gpm @ 0 psig

4. Motor;

1 Hp, 1725 rpm, capacitor start, thermally protected,
115V. ac, single phase.

5. Dimensions;

Unit diameter : 11"

Unit Height : 32"

Tank diameter ; 30"

Tank height ; as required

6. Net Weight; (not including tank)

280 pounds

7. Safety;

The electrical system is protected by a circuit breaker.
The motor is also thermally protected. The system has a
check valve which prevents wastewater from flowing back
into the unit when it is not operating. The>pump itself,
when not operating, serves as a check valve. The pump and
discharge lines are protected by.a relief valve. The re-
lief valve is set to open at 70 to 75 psig. The tank is
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7. Safety; (Cont'd)

equipped with an overflow pipe.

8. Material;

Materials in contact with sewage: Brass; Black Iron;
300 and 400 series Stainless Steel; Neoprene Rubber;
Concrete.
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PUMP GRINDER INSTALLATION (See Figure A-l)

The two support channels are attached to the pump grinder first.
The channels initially are only hand tightened since a final adjust-
ment will be needed. Note the channels should be 12 inches above
the pump grinder. The check valve-relief valve assembly is attached
next. Be sure to use a pipe joint compound on all threaded joints.

Next, install the diaphragm switch assembly. The on/off level
switch and the overflow alert switch are suspended from a common
threaded rod which is attached to one of the support channels. The
on/off switch is located at the same level as the pump grinder inlet,
two inches off the botton of the tank. The overflow alert switch
is located 14 inches below the overflow line.

The tank brackets are installed next. The tank brackets
serve as mounts for the two support channels. They are located
46 inches from the tank bottom. The pump grinder is lowered into
the tank and secured to the tank brackets. To produce the two
inch clearance necessary, adjust the pump grinder depth by means
of the four threaded rods. The two inch clearance is necessary
to insure proper scouring of the tank bottom.

The discharge piping is connected next using as few bends
and elbows as possible.

CONTROL BOX INSTALLATION

The control box is supported by two angles which are attached
to the tank wall. The angles are located so that the control box
can be attached to the angle by the rear hole of each control
box flange. The control box is mounted far enough from the wall
to permit the opening of its door.

ELECTRICAL CONNECTIONS

The pump grinder is equipped with two electrical cables which
must be connected to the control box. The three conductor cable
P4 coming from the motor carries motor current and is connected to
P3 of the control box. The two conductor cable P6 coming from the
motor goes to its capacitor which is located in the control box.
P6 is connected to P5 of the control box.
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INLET LIKE
OVERFLOW LINE
PRESSURE LATERAL
POWER LINE
PUMP GRINDER
CONTROL BOX
VENTED CONCRETE COVER
CONCRETE SEWER PIPE
CONCRETE BASE
SUPPORT CHANNEL
TANK BRACKET
SUPPORT ROD
RELIEF VALVE
CHECK VALVE
UNION
PVC BALL VALVE
LEVEL SWITCH
OVERFLOW SENSOR
FIGURE A-l • PSG INSTALLATION
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The on/off switch Pi is connected to Jl of the control box.
Be sure the vent tube in the cable is pointing downward to prevent
debris from entering. The power line from the house is labeled
P8 and is connected to P7 of the control box.

The control box has a two conductor cable J2 which is connected
to P2 of the data cable. This cable carries a signal indicating
operating time. The overflow alert switch is also connected to the
data cable. Be sure to have the vent tube in the switch cable
pointing downward to prevent debris from getting into the vent tube.
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SYSTEM START - UP
The Pump Grinder may require priming prior to the initial
start-up. This is accomplished by manually opening the relief
valve. Be sure there is enough water in the storage tank to
warrant a start-up, approximately 16 inches. Turn the pump
grinder on, operating it in the manual mode. This is accomplished
by first opening the control box door. Then actuate the circuit
breaker to the "ON" position. Next actuate the toggle switch to
the manual position. The toggle switch is labeled "M" for manual
operation and "A" for automatic operation. When water starts to
come out of the relief valve exit, change the mode of operation to
automatic and immediately close the relief valve. The pump grinder
should begin pumping water through the discharge line. Let the
pump grinder pump down and shut off automatically. Check to see
that the residual water is 7 to 9 inches deep. If the water level
is more than 9 inches deep lower the on/off switch by means of the
threaded rod attached to the support channel. Next, let water
enter the storage tank and note the level at which the pump
grinder starts automatically. This level should be 14 to 16 inches
high. Be sure that the overflow alert switch is 14 inches below the
bottom of the overflow pipe. The control box door is closed and
secured by the two clamps before completing the installation.
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APPENDIX B

CHECK-OFF LIST PROCEDURE

FOR

PHOENIXVILLE PRESSURE SEWER INSPECTION

1. Record cycles and operating time for each unit on the data
form provided.

2. Note overflow condition relative to alert lights.

3. Change Recorder paper and label used roll as to time and
date removed also number of cycles and total operating minutes
of each unit.

4. Install recorder paper and label new roll as to time started and
date, number of cycles and total operating minutes of each unit.

5. Make gas level check on each installation.

6. Note general condition of each data station.

a) Possible piping leaks

b) Unusual operation of instruments

7. Make visual inspection of each unit (2 men required).

a) Note possible overflow

b) Excessive corrosion

c) Sludge build up in the tank

d) General condition of installation
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DATA FORM

FOR

PHOENIXVILLE PRESSURE SEWER INSPECTION
CONDUCTED BY:
ACCOMPANIED BYs
DATE:
TIME:
LOCATION
OVERFLOW
ALERT
(ON/OFF)
CYCLES
(NUMBERS)
TOTAL
OPERATING
(MINUTES)
COMMENTS
NOTE:
IF ANY OF THE OVERFLOW ALERT LIGHTS ARE ON, NOTE IN
THE COLUMN LABELED OVERFLOW LOCATED ON THE DATA FORM.
THEN PRESS THE RESET BUTTON. IF ANY OF THE LIGHTS
STILL REMAIN ON, AN OVERFLOW CONDITION EXISTS.
VERIFY OVERFLOW BY VISUAL INSPECTION. THEN CALL,
AS SOON AS POSSIBLE, GENERAL ELECTRIC, PHILADELPHIA

COMMENT ON ANYTHING WHICH APPEARS UNUSUAL: VIBRATION,
EXCESSIVE SLUDGE BUILDUP, SCALING, CORROSION, CON-
DENSATION, ETC.
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SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
No.
3. Accession No.
w
4. Title PRESSURE SEWER DEMONSTRATION AT
THE BOROUGH OF PHOENIXVILLE, PENNSYLVANIA
7. Awthorfe. Mekosh, G., and Ramos, D.

T. organization:
Philadelphia, Pennsylvania
Re-Entry and Environmental System Division

12.
15. Supplementary Notes
Environmental Protection Agency report number,
EPA-R2-73-270, July 1973.
10. Project No,
11050 FOU
11, Contract/Grant No.
fcOSfpasd'-
16. Abstract
A site was selected at the Borough of Phoenixville, Pennsylvania, which provided
a maximum variable exercise of a pressure sewer system. The site consisted of
five residences spread over more than one-half mile in hilly and predominantly
shale-based terrain. The residences varied from a small house to a multiple-
unit apartment house. The apartment house is more than half a mile in distance
and 60 feet in elevation below the existing conventional gravity sewer inlet
point.
The project proved over a six-month period that a multiple residence pressure
sewer system can adequately store peak loads of wastewater and gtiftd and pump
wastewater through small-diameter plastic pipe to the existing conventional
gravity sewer. During the project, data was collected which provided infor-
mation concerning the 'installation, operation and maintenance of the system,
its technical performance, the variations in that performance during the six-
month period and the characteristics of the wastewater as delivered to the
existing gravity sewer.
17a, Descriptors
*Water pollution control, *Sewers, *Sewage disposal, Plastic pipes,
Pressure conduits, Data Collections, costs.
I7b. *pump-grinders, *Pressure sewers, *Systern monitoring, Cost
breakdown, Wastewater characterization.
17c. COWRR Field & Group
18, Avaikt-ility
Abstractor James
——^—^—
WRSIC 102 «REV. JUNE 19715

reissl
%2. Price
Send To:

WATER RESOURCES SCIENTIFIC INFORMATION CENTER
US. DEPARTMENT OF THE INTERIOR
WASHINGTON. DX. 20240
—Environmental Protection agency. Ejatipnaj
.nstituuwuEnvironmental Research Center, Cinti,0hio
Q P Q 488-935
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