USA > Massachusetts > Essex County > Andover > Town annual report of Andover 1930-1934 > Part 16
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11,125.
2,920.
14,045.
38.5
150,000
54,750,000
11,125.
3,380.
14,505.
26.5
200,000
73,000,000
11,125.
3.840.
14,965.
20.5
250,000
91,250,000
11,125.
4,300.
15,425.
16.9
300,000
109,500,000
11,125.
4.760.
15,885.
14.5
350,000
127.750,000
11,125.
5,220.
16,345.
12.8
400,000
146,000,000
11,125.
5,680.
16,805.
11.5
450,000
164,250,000
11.125.
6,140.
17,265.
10.5
500.000
182,500,000
11,125.
6,600.
17,725.
9.7
500,000*
182,500,000
14,875.
7,100.
21,975.
12.0
per day
per yr.
* After auxiliary source is constructed at a cost of $30,000.
During the first few years the consumption of water will be much less than the requirements after the school is fully devel-
8
oped so that the charges for water during this period of develop- ment will be influenced largely by the fixed charges. When the consumption reaches 275,000 gallons per day, or slightly more than one-half the ultimate demand, as estimated by the State De- partment, it will be practical to establish a meter rate of 16.0c per 1000 gallons with a sliding scale decreasing to 12.0c when the consumption is 500,000 gallons per day or more.
Consumption Gallons per yr.
Minimum Charge per yr.
Rate per 1000 gals.
$11,125.
20,000,000
13,630.
40,000,000
14,135.
60,000,000
14,625.
80,000,000
15,140.
100,000,000
16.0c
120,000,000
15.0
140,000,000
14.0
160,000,000
13.0
180,000,000
12.0
No change was suggested in the proposed sewer for the school
GAS:HBG
Yours very truly, WESTON & SAMPSON
January 12, 1932.
Board of Public Works,
Andover, Mass.
GENTLEMEN :
In response to your request we herewith submit a report on pumping equipment for Haggetts Pond pumping station. This problem has been under consideration for over three years with- out any decision as to the type that would best meet the needs of the Town. We wish to state, and your Board is already appre- ciative of the fact, that the present pumping equipment, consist- ing of a Deane steam pump installed in 1894 and an electric- motor-driven centrifugal pump, does not furnish a sufficient
9
guarantee of an uninterrupted water supply. The Town should take immediate steps to provide another pumping unit.
CENTRIFUGAL PUMP
In June of last year your Board replaced the then existing centrifugal pump, installed in June 1924, with a new centrifugal pump using the same 200 HP motor. The new pump was de- signed for 1200 gallons per minute against a total pumping head of 300 ft. when operating at a speed of 1775 RPM with a pump efficiency of 80%. A pumping test on June 17 gave 1303 g.p.m. against a head of 295.2 ft. at 1775 RPM, resulting in a 'pump efficiency of 81%. The pump was accepted and placed in con- tinuous operation on June 19, 1931.
On April 22, 1931, a venturi meter and register were installed in the pumping station to record the rate and amount of pumping. Careful records have been kept of the pumping heads, electric power consumed and other items entering into the cost of pump- ing water with this new centrifugal pump. From the six months' records (July to Dec. 1931) the following average results have been tabulated.
During the operation of this pump, one steam boiler has been kept with a banked fire, even during the summer months, in order to allow the Deane steam pump to be available for emergencies. This procedure seems to be advisable considering the rather limited storage and low pressure from your reservoir and because certain outlying districts do not have sufficient pressure for fire service unless a pump is in operation. Should the centrifugal pumping unit fail by reason of interruption in the electric power, or because of an accident to the motor, pump or switchboard. about 8 hours would elapse before the steam pump, starting with a cold boiler, could be properly placed in operation, as against about 1 hour with a banked fire.
The average amount of coal used for banking fires is about 500 lbs. per 24-hour day. Inasmuch as the coal required for heating the pumping station and the engineer's residence is in- cluded in the steam pump operation, both these items have been
10
included in the tabulation for the electric pump. The price for coal is $5.72 per net ton which is the average cost delivered at the pumping station during the year 1931.
TABLE I ELECTRIC PUMP
Electric power
Month 1931
Gallons pumped
Hours in Oper- ation
Rate Total of Pump- Pump- ing ing Head Kw. Hrs. (GPM) (Ft.) used
Cost Coal for Cost of per Mg. banking power @ 1-1/4 c and and coal heating per Mg.
July
30,280,000
13-10
1236
292.3
41,400
17.09
1.52
18.61
Aug.
29,467,000
12-47
1240
288.7
40,400
17.14
1.48
18.62
Sept.
28,507,000
12-51
1231
297.6
39,400
17.28
1,55
18.83
Oct.
28,341,000
12-35
1211
294.6
39,500
17.42
1.88
19.30
Nov.
24,555,000
11-32
1181
297.4
34,800
17.72
2.53
20.25
Dec.
23,311,000
10-38
1180
297.0
33,400
17.91
2.81
20.72
Total
164,461,000
228,900
Av'ge
27,410,167
12-15
1213
294.6
38,150
17.43
1.96
19.39
DEANE STEAM PUMP
Before the installation of the new centrifugal pump, the Deane steam pump was operated regularly except for sufficient use of the old centrifugal pump to absorb the standby charges for elec- tric power, amounting with discount to $180 per month.
The following results of operation for the Deane pump are obtained from the pumping station records for January to June, inclusive. The gallons pumped previous to April 22 are based on the readings of the revolution counter with an allowance for slip equal to the difference between the displacement of the plungers and the venturi meter readings from April 22 to June 18, during which period both the revolution counter and venturi reg- ister were recorded. The slip amounts to 7%.
The coal used includes running the pump, banking fires and heating the pumping station and engineer's dwelling during the days that the steam pump was in operation.
1
11
The pumping heads were obtained from the results of various pump tests at different rates of pumping.
TABLE II DEANE STEAM PUMP
Month 1931
Gallons pumped
Hours in Opera- tion
Rate of Pump- ing (GPM)
Total pump- ing head (Ft.)
Coal for running, banking and heating (Lbs.)
Cost of Coal per Mg.
Jan.
15,130,000
11-42
980
272.2
56,800
10.73
Feb.
13,975,000
12-49
956
270.0
52,500
10.73
Mar.
15,280,000
12-48
948
269.3
59,100
11.06
Apr.
16,324,000
14-06
965
270.9
61,500
10.77
May
20,358,000
15-00
983
272.5
67,300
9.46
June
15,373,000
14-58
1007
274.7
48,600
9.05
Total
96,440,000
345,800
Av'ge
16,073,000
13-32
973
271.5
57,630
10.25
During the above six months 46,290,424 gallons of water, in addition, were pumped by the old and new centrifugal pumps, making a total of 307,191,424 gallons for the year 1931.
A Venturi meter which is a device for measuring the quantity of water pumped has been installed at the Haggetts Pond Pump- ing Station. This installation was completed on April 22nd. A concrete manhole was built around the Venturi throat which was installed in the main discharge line.
A Tycos pressure recording gauge has been installed at the pumping station at Haggetts Pond. Each chart used with this device is a 24 hour pressure record, and incidentally the gauge is equipped with an electric device which causes a gong to ring in the engineer's house if the water pressure at the station is reduced due to a big leak in the system or an exceptionally heavy use of water.
12
An instrument which records the elevation of the water in the low service reservoir has been installed at the pumping station at Haggetts Pond, and also a pipe containing water from which the elevation of Haggetts Pond can be obtained.
A chlorinator has been installed at the Haggetts Pond pumping station to sterilize the water. At certain times during the year especially when the freezing weather commences, water supplies show a larger bacteria content and often times this is greater than the standard set by the State Board of Health for a safe water supply. It is a well-known fact that chlorination has done more to reduce water borne typhoid fever than any other measure, and with this in mind the chlorinator was installed as a precautionary measure upon instructions by the Board of Health. I might add that in some states it is compulsory to chlorinate every municipal water supply.
At the Haggetts Pond pumping station a 2-inch water line has been installed running from the 12 inch discharge line on the street side of the 12-inch gate to the pumping station. This makes it possible to obtain water in the station when the 12-inch gate is closed.
The equipment for priming the new electric pump at the Hag- getts Pond station was put into operation May 18th, and has proved very satisfactory.
In compliance with the suggestion of Mr. H. O. Cook, Chief Forester of the Dept. of Conservation, more deciduous trees in- cluding all trees which shed their leaves annually have been re- moved from the edge of the pond, and evergreen trees have been transplanted in a number of places where the deciduous trees have been cut down. It has been stated by tree experts relative to the consumption of water by deciduous trees versus the ever- green or coniferous trees, that for every pound of leaf material that falls from the deciduous trees in the fall of the year, 56 gallons of water are required for its growth. A well developed tree grows about 20 pounds of leaves per year, and as the average of trees per acre is about 250, it is obvious that a generous quan- tity of water is thus consumed. It will be interesting to note
13
. that an evergreen tree requires only 5 gallons of water to produce one pound of needles.
Piston rings in the oil engine at the Bancroft Road pumping station have been renewed and a check valve at the same station has been reconditioned.
During 1931 307,191,424 gallons of water were pumped at the Haggetts Pond Pumping Station, or a daily average of 841,620 gallons. The steam pump was in operation 1649 hours and 35 minutes, the old electric pump 417 hours and 15 minutes, and the new electric pump 2407 hours and 40 minutes, making an average daily run of 12 hours and 15 minutes. On July 28th the greatest amount of water was pumped, namely 1,385,000 gallons, and the banner week was that of August 2nd to 8th inclusive during which time 7,716,000 gallons were pumped. Incidentally the re- ceipts from water rates during 1931 amounted to $42,573.20 which is the highest amount received since the installation of the system.
To provide for adequate water maintenance during 1932 we recommend an appropriation of $27,950.00 to be divided sub- stantially as follows :
Maintenance :
Salaries and Labor
$17,000.00
135 tons of Coal (average 800 lbs. per day ) 900.00
12 tons Coal No. 2 Station and Shop 200.00
Engine Oil and Tools 500.00
Power No. 1 and No. 2 Stations
8,000.00
Truck and Car 500.00
Steam Engine, Boiler and Property Repairs 850.00
-
$27,950.00
Services and Meters increased during 1931 as follows :
Services in use January 1, 1931
2351
Services installed during 1931 33
Services in use January 1, 1932
2384
Meters in use January 1, 1931 2227
14
Meters installed during 1931 Meters in use January 1, 1932
34 2261
During the year 1931 we have laid 1683 feet of service pipe on private property and 621 feet on Town property. A number of water services were renewed during 1931.
We recommend for service pipe and construction for' 1932, $9850.00 to be divided substantially as follows :
Service Pipe and Construction :
Labor
$6000.00
Meters and Parts
300.00
Pipe, all kinds
1700.00
Brass goods, tools and hydrants
600.00
Renewing services
1250.00
$9850.00
Appropriation March 1931
Water Maintenance
$35,000.00
Transferred from Reserve
850.00
$35,850.00
Water Construction
20,000.00
Total
55,850.00
Approved bills
55,045.29
'Balance
804.71
RECEIPTS
Water Rates
42,573.20
Water Construction
2,902.00
Paid to Town Treasurer :
Water Rates
42,573.20
Construction
2,902.00
Total
$45,475.20 $45,475.20
15
TYPES OF NEW PUMPING EQUIPMENT
The new centrifugal pump was installed to replace a former unit that could not be operated with reasonable economy and, incidentally, to obtain information on the cost of pumping by electric power under favorable conditions. These data are avail- able for a six months' operating period and it is now possible to compare the various types of pumping machinery that may be installed at Haggetts pond station with this information at hand.
It may be of interest to know that in our comparison of De- cember 21, 1929, we estimated the cost of electric power for pumping 1,000,000 gallons per day against a head of 295 ft. to be $7000 per year, or $19.18 per Mg. Electric power was based on the following contract rates, as proposed by the Lawrence Gas & Electric Company, under date of December 3, 1929.
First 25,000 Kw. hrs. per month @ $.01425
Next 75,000 Kw. hrs. per month @ $.01355
All over 100,000 Kw. hrs. per month @ $.01125
On the basis of power at $.0125 per Kw. hr .- which as you recall, is a special rate allowed for one year because of your in- experience in the use of restricted electricity for pumping water- our estimate for electric power would have been $17.10 per Mg. as compared with the actual cost of $17.43.
We have considered several types of pumping machinery, all of which have been successfully operated at various water works pumping stations. The results of the various studies are sum- marized in Tables III and IV.
Table III is a comparative summary of the cost of pumping water with the main pumping unit having a capacity of 2100 GPM, or 3,000,000 gallons per day which would be required pro- vided the proposed State School is located in Andover and the Town should decide to furnish the School with water up to 500,000 gallons per day, as estimated by the Department of Mental Diseases.
Table IV is a comparative summary with a pumping capacity of 1400 GPM, or 2,000,000 gallons per day which would be re- quired for the Town only.
16
Some of the considerations that should govern the choice of pumping machinery are as follows :
(1) Cost of pumping water per Mg.
(2) Cost of installation.
(3) Dependability.
(4) Flexibility.
STEAM PUMPING ENGINE
The fuel economy of pumping water with a Laidlaw high duty steam pumping engine is without an equal except for the Diesel oil engine. The steam pump is also most dependable and very flexible as to the rate of pumping or change in pumping head. The cost of installation, however, is high and had two pumps been considered as for the other types of pumping equipment in Columns 3, 4, and 5, to give a complete duplicate unit, the cost would have been higher than for the Diesel oil engine.
The present Deane steam pump has now been in operation as the main pumping unit for so many years and is of such limited capacity that it is no longer available for a dependable spare unit, especially if the State School is located in Andover. With one new steam pumping engine it would be necessary to provide another auxiliary unit which may best be accomplished by re- taining the present electric pump. This means a standby charge of $180 per month for electricity which would be used up by operating the electric pump for several days each month. The cost of pumping is thereby increased by $1020 per year which, together with the other operating expenses, results in a cost per million gallons about equal to the Diesel oil engine, somewhat more than the steam turbine and considerably less than the elec- tric pumps.
DIESEL ENGINE CENTRIFUGAL PUMP
. The Diesel oil engine furnishes power for pumping water at a minimum cost. The cost of installation, however, represents a considerable investment, even for one unit.
Although some difficulties have been experienced with Diesel engines for operating pumping machinery it is quite certain that
17
· two units would provide dependability. The speed of the Diesel engine, as for the steam pumping engine and steam turbine, may be readily increased or decreased to alter the rate of pumping without any appreciable change in economy.
The space occupied by this type of pumping equipment is about equal to the steam engine and both require an addition to the pumping station. The cost of pumping water per million gallons, on account of the fixed charges, is higher than for the steam turbine. With one new Diesel oil engine centrifugal pump and by retaining both the present steam pumping engine and elec- tric pump, the cost per Mg. would be decreased about $1.50 per million gallons.
Any major repairs to the engine are expensive and need the services of an experienced mechanic. The Diesel engine is yet in the development stage, particularly as to speed of operation.
ELECTRIC CENTRIFUGAL PUMP
The cost of electric power at the rates proposed by the Law- rence Gas & Electric Co. is more than double the cost of coal for the steam pumping engine. The cost of installation, however, is a minimum so that there is a considerable saving in fixed charges. An electric-motor-driven centrifugal pump depends for its op- eration upon electric power from an outside source and although quite dependable it is considered good insurance to provide an- other form of power, and the gasoline engine is adapted to this purpose. A new motor-driven and gasoline-engine-driven cen- trifugal pump may be installed in the present station without re- moving the steam pump. The present steam pump is of limited capacity and if electric pumps are operated as the main unit, it would seem preferable to abandon steam power and install a gasoline-engine-driven centrifugal pump of 2100 or 1400 GPM capacity, depending upon the state school.
The cost of pumping water with an electric pump is several dollars per million gallons more than by any other type of pump- ing equipment. A motor-driven centrifugal pump is designed for a particular capacity, pumping head and speed, so that it is
18
impossible to vary these factors without an unreasonable sacri- fice in efficiency and cost for electric power.
STEAM TURBINE CENTRIFUGAL PUMP
The increase in the efficiencies of centrifugal pumps in the past few years, together with some improvements in steam turbines and gears, have resulted in an economy approaching the steam pumping engine. There is no question regarding dependability as is proven by the many installations operating 24 hours per day for several years without criticism. The cost of installation is moderate and the small space occupied would allow two units to be installed within the present station without removing either the steam pump or electric pump.
One of the advantages of this type of pumping unit is its great flexibility of operation. A small variation in speed, readily con- trolled by the steam throttle, will correspondingly change the capacity of the centrifugal pump and this result is accomplished at practically full economy. Another decided advantage is that exactly the same turbine and pump would be installed and at the same cost regardless of the state school. The unit would be cap- able of delivering 2100 GPM against a pumping head of 315 ft. or any lesser quantity as desired.
It is assumed that the present boilers will be used with a steam pressure of 120 lbs. at the turbine. Should it be necessary within a few years to replace one of the boilers the steam pressure would be increased to at least 150 lbs. which would result in an improved turbine efficiency sufficient to equal the fixed charges on the in- vestment.
A comparison between Columns 5 and 7 in both Tables III and IV shows that there is very little difference in the cost of pump- ing whether two steam turbines are installed with the steam pumping engine as an auxiliary, or one steam turbine with both the steam pumping engine and the electric pump as auxiliaries, because the fixed charges on the second turbine unit about offset the additional cost of pumping with the electric pump for the purpose of consuming the standby charge for electricity amount-
19
· ing to $180 per month. In view of an installation cost of $20,- 000, as compared with $32,000, and because the retention of the electric pump constitutes an independent source of power, we favor one unit.
A comparison between the cost of operating an electric and steam turbine station, as given in Columns 6 and 7, shows the following results :
With the state school the $10,000 additional invest- ment for a steam turbine would be saved from operating costs in two and one-half years.
Without the state school the $11,500 additional in- vestment for a steam turbine would be saved from op- erating costs in about five years.
CONCLUSIONS
As a result of our study we conclude-
That a steam-turbine-driven centrifugal pump best combines the advantages found in the other types without some of the dis- advantages.
That the installation cost is moderate.
That the cost of pumping water is a minimum.
That the flexibility of the unit allows an installation which can be operated with equal advantage, with or without the state school.
That with this additional pumping unit the Town would be assured of an uninterrupted supply of water by retaining the present electric pump.
RECOMMENDATIONS
We submit the following recommendations-
That one new steam-turbine-driven centrifugal pumping unit be installed at the Haggetts Pond pumping station.
That the present Deane steam pumping engine be retained as a reserve unit.
That the present electric-motor-driven centrifugal pump be re- tained as an auxiliary unit.
That the sum of $20,000 be provided for this purpose.
Respectfully submitted,
WESTON & SAMPSON
20
Tables III and IV
Comparison of Pumping Equipment
TABLE III
Town of Andover -- Comparison of Pumping Equipment BY WESTON & SAMPSON January 11, 1932
With State School-1500000 Gallons Per Day
TYPE
ITEM
Steam Pumping Engine
Diesel Oil Engine Centrifugal Pump
Electric Centrifugal Pump
Steam Turbine Centrifugal Pump
Electric Centrifugal Pump
Steam Turbine Centrifugal Pump
PUMPS
1-2199gpm. @ 315' head. Laidlaw
head
1-2100 gpm. @ 315'| 1-2100 gpm. @ 315' head
1-2100 gpm. @ 315' head
1-2100 gpm. @ 315' head
1-2100 gpm. @ 315' head
High Duty
1-2100 gpm. @ 315' 1-2100 gpm. @ 315' head head
1-2100 gpm. head
@ 315'
Gasoline Engine
Pumping 1-Electric Centrifu-|1-Steam
Pumping|
1-Electric Centrifu-| 1-Electric Centrifu- gal Pump 1200 gpm. @ 300' head
Present Pumps
1-Electric Centrifu-| 1-Steam gal Pump 1200 gpm @ 300' head 1-Steam Pumping Engine, 1050gpm. @ 280' head
Engine, 1050 gpm @ 280' head
gal Pump 1200 gpm. head
@ 300'
head
1-Steam
Pumping
Engine 1050 gpm. @ 280'
Pumping Engine 1050 gpm. @ 280' head
head
gal Pump 1200 gpm. @ 300' head 1-Steam
Engine 1050 gpm. @ 280'
New Pumps
CONSTRUCTION COST New Pumps
1-Pumping Engine $25000
1-Pump, En- gine, etc. Foundation, Piping, Oil Tanks, etc. Building Ad- dition 4.000
$20000
$2900
1-Pump, Tur- bine, etc. $14000 Foundation, Piping, Changes in Station, etc. 6000
1-Pump and Motor Foundation, Piping, Wir- ing, Changes in Station, etc. 5600
$2900
1-Pump, Tur- bine, etc. $14000 Foundation, Piping, Changes in Station, etc. 6000
Total
$37000
$54000
$17500
$32000
$8500
$20000
OPERATING COST Fixed Charges
6.4% x $37000 $2368 8% x $54000
$4320
8% x $17500 $1400 7450
7% x $32000 $2240
8% x $8500
$680 7% x $20000
$1400
Fuel or Power
3370
2700
3980
7450
3980
Coal for Banking or Heating Maintenance Attendance
1000
600
400
600
300
600
4400
4400
4400
4400
4400
4400
Extra Cost-Elec- tric Power
1020
-
-
-
1020
Total Cost Per Mg.
$12158
$12345
$13975
$11220
$13480 $36.95
$11400
$33.30
$33.80
$38.30
$30.75
$31.25
1-Pump and Engine Foundation, Piping Tanks, etc.
9000
1-Pump, Tur- bine, etc. Foundation, Piping, etc. 2500
9500
1-Pump, En- gine, etc. 19000 Foundation, Piping, etc. 3000
8000
1-Pump and Motor Foundation, Piping, Wir- ing, Changes in Station, etc. 5600
Foundation, Piping, etc. 8000 Building Ad- dition 4000
325
325
-
650
TABLE IV
Town of Andover - Comparison of Pumping Equipment BY WESTON & SAMPSON January 11, 1932
Without State School-1,000,000 Gallons Per Day
TYPE
ITEM
Steam Pumping Engine
Diesel Oil Engine Centrifugal Pump
Electric Centrifugal Pump
Steam Turbine Centrifugal Pump
Electric Centrifugal Pump
Steam Turbine Centrifugal Pump
PUMPS
New Pumps
1-1400 gpm. ( 315' head Laidlaw High Duty .
1-1400 gpm. @ 315' head
1-1400 gpm. @ 315' 1-1400 gpm. @ 315' head
head ( Gasoline Engine )
1-2100 gpm. @ 315' head operated 1400 gpm. 1-2100 gpm. @ 315' head operated @@ 1400 gpm.
1-1400 gpm. @ 315' head
1-2100 gpm. @ 315' head (operated @
1400 gpm.)
1-Electric Centrifu-| 1-Steam Pumping Engine
1-Electric Centrifu- 1-Steam Pumping Engine
gal Pump 1200 gpm. @ 300' head
1050 gpm. @ 280' head
gal Pump 1200 gpm. @ 300' head
1050 gpm. ( 280' head
1-Electric Centrifu- gal Pump (1200 gpm. @ 300' head
1-Electric Centrifu- gal Pump (1200 gpm. @ 300' head)
Present Pumps
1-Steam Pumping Engine 1050 gpm. @ 280' head
1-Steam Engine (1050 gpm. @ 280' head ) Pumping 1-Steam Pumping Engine (1050 gpm. @ 280' head)
1-1400 gpm. ( 315' head
CONSTRUCTION COST
New Pumps
Foundation,
Foundation, Piping, Oil Tanks, etc. 8000
Foundation, Piping, Wir- ing, Changes in Station, etc. 6500
1-Pump, Tur- bine, etc. $14000 Foundation, Piping, Wir- ing, Changes in Station, etc.
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