Evening capital and Maryland gazette. (Annapolis, Md.) 1910-1922, 1922-03-23

sewage flow in city with few indus
trial enterprises is generally taken 10
be equal TO the water consumption,
the ground water infiltration into the
sewers about balancing the water con-
sumption which does not reach them.
Upon this basis the average daily sew
age flow in 1855 will be 1920 900 gal
Ions and in 1920. 100000 gallons,
both exclusive OF the sewage original
ing on the Naval Academy grounds.
The water consumption at the Naval
Academy is said 10 be 100000 gallons
daily, OF which 100000 gallons reach
the sanitary sewers. No one can
prophesy what the future of the Naval
Academy will be, but its expansion is
not likely 10 be great. Whether or not
he Naval Academy sewage is at first
discharged into the main drainage
system OF Annapolis. il would be un-
iafe not to take account OF this added
burden on the sewers. and a figure OF
1000, 900 gallons per "a hours is taken
IS the basis for arriving al the sizes OF
he sewers In the project The cost
stimate for the treatment works is
,ased upon a size of works sufficient
o handle an average daily flow of only
100000 gallons il the sewage from
he Naval Academy is TO be added
hese works should provide for flow
lot less than 100000 gallons per day
Owing to the monthly. daily and
lourly variation in a city's water con-
sumption and TO fiuctuating ground
water levels, sewer must be design
d to carry when full a much larger
uantity OF liquid than would be ac-
ounted for by the average sewage
ow. The peak of discharge in a
ever has teen found to vary with the
oiume of average sewage flow. IL be-
ag somewhat less pronounced the
anger the average volume of sewage
D be handled. For an average daily
low OF 100000 gallons. sewer
should have a full carrying capacity OF
lbout 100000 gallons, while for an
average flow OF 100000 gallons daily
a full carrying capacity of 3,2500OC
gallons should be allowed.
The capacity of the main collecting
sewer in the project. therefore, has
cen fixed at 100000 gallons daily
when Rowing full. and the smaller in
trceptng sewers have been designed
lpon the same principle. The pump
ng station, however, should take all
he sewage that will come TO it at any
time, and with number Of street in
lets connected to the sewers, as is the
case with Annapolis, the flow in the
main drainage system during storms
will be as large during the early years
as it will be in dry weather thirty
years hence The excess Of sewage
pumped TO the treatment works dur
ing storms, before these works have
been enlarged to equal the capacity oil
pass to the river though an overflow
Estimate OF Cost
The photography and topography
of Annapolis and its vicinity are not
favorable to inexpensive collection oil
he sewage The irregular shore out.
inc. the deeply inaenting creeks and
he high promontories and low gullieg
bordering them make necessary the
construction of deep sewers on fiat
slopes A considerable part of the
;ystom must lie below tide level a
condition which will also influence
materially the cost. The following
abulation is an approximate estimate
If the cost OF the project. based upon
current prices. Detailed surveys ana
plans may indicate the possibility Of
certain reductions in the estimate.
Main Drainage System
East Intcreepting Sewer n d
Branches. ................
West Intercepting Sewer a md
Branches. ....-.....'''.'
Main Collector .................
Inverted Siphon under Spa Creek
'.''''''''A" an"
Total,
Pumping Station and Equipment-Ca
day. % lift ................'.
Force Main to Treatment Works-24