-------
studies using synthesized combined sewage particles [29, 30]. Both units are
designed as a function of the inlet diameter. For the swirl concentrator, the
inlet diameter is related to the chamber diameter by curves developed for
different efficiencies of settleable solids removal [29]. Some problems do
exist, however, when using the design curves for inlet dimensions and flows
that do not fall within the range presented in the curves. Additional
modeling and study are required to expand the curve usability to meet flow and
inlet sizes encountered in field applications. It is also recommended that
emergency side overflow weirs be provided in the swirl design [41, 67]. A
general design layout of the swirl concentator/regulator is shown in Figure
47.
General design layouts of the helical bend concentrator/regulator are shown in
Figure 48. Model studies showed that the optimum interior angle was
approximately 60 degrees. The design details for the helical bend are for
1001 grit (0.2 mm, S.G. = 2.65) removal.
Swirl Degri_tter—Design criteria and design curves for discharges from 0.1 to
2.5 m^/s (2.3 to 57 Mgal/d) have been developed through hydraulic model
studies using synthetic grit particles [68].
Swirl Primary Separator—Detailed design instructions, criteria, and design
curves for flowrates from 0.5 to 5QO L/s (0.01 to 11.4 Mgal/d) have been
developed from hydraulic and mathematical models for the swirl primary
separator [39]. The conical shaped configuration of the device utilizes a
height equal to its diameter, which should enhance sludge concentrations but
also may decrease cost competitiveness in large sizes.
Design Criteria for Physical Process Equipment—Design and operational
criteria have been reported for the screening alternatives, dissolved air
flotation, high rate filtration, and high gradient magnetic separators, and
are summarized in Tables 94 through 99 [2, 281. The design parameters
generally reflect ranges of operational limits experienced in a number of
field installations.
Costs of Physical Treatment Alternatives—
Construction cost and average operation and maintenance costs for physical
treatment processes are presented as a guide for planners to determine the
relative economic impacts of various treatment alternatives on a first cut
basis. Detailed cost studies are still required, including local conditions
or changing design requirements, when preparing estimates for specific
application or final selection of alternatives. .
Construction cost and operation and maintenance cost curves have been
developed for combined sewer overflow treatment facilities ranging in size
from 0.2 to 8'.8 m3/s (5 to 200 Mgal/d), and for storage facilities ranging in
size from 3.8 to 908 ttL (1 to 240 Mgal) [27]. Facilities include: storage,
sedimentation, screening, swirl concentrator/regulator, dissolved air
flotation, filtration, disinfection, chemical feed systems, flow measurement,
and raw wastewater and sludge pumping stations. Costs represented by these
curves do not include cost of land, engineering, and contingencies.
211
-------
INLET, CHAMBER DIAMETERS
WEIR, SCUM RING DIAMETERS
INLET DETAIL
2 — :
tr
i jj
v-^
.— •
n
v
i
"i!
WEIR, SCUM R
IHfi DETAILS
CENTERLINE PRIMARY GUTTER
CENTERLINE SECONDARY GUTTER
1 USE If M Cl IMCf
D - CURVES [die]
0 « 2/3
"4 - 5/8 0
h - D /2
h2- °/3
R, - 7/18 D,
- 5/48
R - 3/IB
- 11/18
R. - CURVE SKOOTHEO
IN TO MEET
INLET CEHTERUHE
Figure 47. General swirl concentrator/regulator design details [29].
212
-------
WE I R
SECTION A-A
TIPICH SECTION B-B
Figure 48. Recommended plan and section
details for the helical bend concentrator/regulator [30],
213
-------
TABLE 94. DESIGN PARAMETERS FOR HICROSTRAINERS,
DRUM SCREENS, AND DISC SCREENS
Parameter
Screen aperture, microns
Screen material
Drum speed, r/min
Speed rangs
Recomended speed
Submergence of drum, %
Flux rate, gal/min per
ft2 of submerged screen
Headloss, in.
Backwash
Volume, % of inflow
Pressure, Ib/in^
Microstrainers
23-100
Stainless steel or plastic
2-7
5
60-80
10-45
10-24
0.5-3
30-50
Drum screen
100-420
Stainless steel or plastic
2-7
5
60-70
20-50
6-24
0,5-3
30-50
Disc screens
45-500
wire cloth
5-15
* * * *
50
20-25
18-24
...a
—
a. Unit's *aste product is a solids cake of 12 to 15% solids content.
gal/ram-ft2 x 2.445 = ra3/h-m2
in. x 2.54 = cm
ft x 0,305 = cm
lb/1n.2 x 0.0703 = kg/cm2
TABLE 95. DESIGN PARAMETERS FOR ROTARY SCREENS
Screen aperture, microns
Range 74-167
Recommended aperture 105
Screen material Stainless steel or plastic
Peripheral speed of screen, ft/s 14-16
Drum speed, r/nrin
Range 30-65
Recommended speed 55
Flux rate, gal/ftZ-nrtn 70-150
Hydraulic efficiency, % of inflow 75-90
Backwash
Volume, % of Inflow 0.02-2.5
Pressure, Ib/in2 SO
ft/s x 0.305 = ra/s
ga1/ft2.min x 2.445 = m3/m2.h
Ib/in2 x 0.0703 = kg/cmZ
214
-------
TABLE 96. DESIGN PARAMETERS FOR STATIC SCREENS
Hydraulic loading, gal/mln per
ft of width 100-180
Incline of screens, degrees
from vertical 35a
Slot space, microns 250-1 600
Automatic controls None
a. Bauer Hydrasieves (TH) have 3-stage
slopes on each screen, 25°, 35°,
and 45°
gal/mfn-ft x. 0.207 = L/ra-s
TABLE 97. OESIGN PARAMETERS FOR DISSOLVED AIR FLOTATION
Overflow rate, gal/ft^ m\n
Low rate 1.3-4.0
High rate 4.0-10.0
Horizontal velocity, ft/rain 1.3-3.8
Detention time, mm
Flotation cell range 10-60
Flotation cell average 25
Saturation tank j-3
Mixing chamber ~\
Pressurized flow, ''. of total flow
Split flow pressurization 20*30
Effluent recycle pressurization 25-45
Air to pressurized flow ratio,
standard rt3/min-100 gal 1 0
Air to solids ratio 0.05-0.35
Pressure in saturation tank, Ib/inH 40-70
Float
Volume, 7 of total flow 0.75-1.4
Solids concentration, % dry weight basis 1-2
gal/ft2-rain x 2 445 = m3/m2-h
ft/mm x 0 00508 = m/s
standard ft3/min 100 gal x 0.00747 = mS/mln-lOO L
x 0.0703 =
215
-------
TABLE 98. DESIGN PARAMETERS FOR DUAL MEDIA
HIGH RATE FILTRATION
Filter media depth, ft
No. 3 anthracite 4-5
No. 612 sand 2-3
Effective size, mm
Anthraci te 4
Sand 2
Flux rate,
Range
Design
Headless,
Backwash
Volume,
A1r
Rate,
Time,
Water
Rate,
Time,
ft
% of inflow
standard ft3/min-ft2
mfn
gal/ft2.min
mm
8-40
24
5-30
4
10
10
60
15-20
ft x 0.305 <= m
gal/ft2.rmn x 2.445 = m^/m^-h
standard ftS/mln-ft2 x 0.305 =
TABLE 99. PRELIMINARY DESIGN PARAMETERS FOR HIGH
GRADIENT MAGNETIC SEPARATORS [28]
Magnetic field strength, k6a 0.5-1.5
Maximum flux rate, gal/ft^-imn 100
Mini mum detention time, min 3
Matrix loading, g solids/g of
matrix fiber 0 1-0.5
Magnetite addition, rag/L 100-500
Magnetite to suspended solids ratio 0.4-3.0
Alum addition, mg/L
Range 90-120
Average 1QO
Polyelectrolyte addition, mg/L 0.5-1.0
a. kG = kilogauss
ga1/ft2-m x 2.445 = m3/m2.n
216
-------
Representative facilities costs are presented in the following paragraphs,
utilizing actual construction cost bid tabulations and estimates from
stormwater facilitiestogether with data used to develop the detailed cost
curves [27]. All costs are adjusted to the ENR 2000 cost index to be com-
patible with values presented in "Urban Stormwater Management and Technology,
An Assessment" [2],
A qeneral comparison of the cost of the various physical treatment processes
is presented in Table 100. The ranges of costs were estimated, and in some
cases, adjusted to a plant capacity of 1.10 m3/s (25 Mgal/d). Average
capacity costs reflect an approximate cost for a treatment process group
indicating relative differences in magnitude between other processes.
TABLE 100. SUMMARY OF AVERAGE CONSTRUCTION COSTS
FOR 25 Mgal/d PHYSICAL TREATMENT FACILITIES3
Physical Construction Average
treatment process costs, $ cost, S/Hgal-d
Sedimentation13 238 000-850 000 23 000
Swirl concentrator/
regulator^ 50 000-65 000 4 500^
Screeningu 400 000-600 000 19 000
Dissolved air
flotation' 600 000-1 200 000 34 000
High rate filtration 1 400 000-1 700 OQO 58 0009
High gradient
magnetic separation 2 113 000 84 500
a ENR 2000.
b. Adjusted to 25 Mgal/d costs.
c. Range for 90 and 100% grit removal.
d. Based on a 12 MgaT/d facility
e. Estimates include supplemented pumping where used.
f. Based on hydraulic loading rate of 5 760 ga1/ft2-d--
includes processing and chemical addition facilities.
g. Based on hydraulic loading rate of 24 gal/ft^ rain--
includes prescreening and chemical addition facilities,
Mgal/d x 0.0438 = m3/s
gal/ft2 d x 1.698 x 10"3 = m3/mz-h
gal/ft2-min x 2.445 = nH/mZ'h
Costs of Sedimentation Faci1ities--Costs of sedimentation facilities are
summarized in Table 101, with flow capacities based on a theoretical 30 minute
detention time to provide an equal basis of comparison. Actual detention
times based on maximum flowrates range from approximately 8 minutes [17] to
over 1 hour [33].
Concentrator/Regulators Costs—Costs of swirl concentrator/regulators are
based on estimates and actual construction costs excluding land costs, bypass
sewers, and engineering and contingencies [27, 30]. Construction costs for
swirl facilities are presented in Figure 49 for swirl chamber diameters of
3.05 to 15.2 ni (10 to 50 ft).
217
-------
TABLE 101. SUMMARY OF COSTS OF TYPICAL SEDIMENTATION FACILITIES8
Flow Construction Annual operation
capacity, costs, Cost, and maintenance
Project location Mgal/cF l/Hgal-d $/acre cost, $/Mgal-d
Boston, Massachusetts
Cottage Farm [17] 62 4 104 000 420 1 280
Charles River
[19, 20] 5? 6 164 700 3 160 1 690
Columbus, Ohio [12]
Whlttler Street 180,0 34 000 210
Dallas, Texas £33]
Bachman Stornwster
Plant
Milwaukee,
Hisconsln [13]
Humtooldt Avenue
New York Cfty,
New York
Spring Creak
[2, 22, 2S]c
Saginaw, Michigan [34]
S7.6 31 900
187 0 9 500 3 100
595 0 20 060 3 660
168.0 19 760 2 040
720
270
170
200
a, ENR = 2000.
b. Based on 30 minute detention time.
c Neglecting 13.0 Hgal of trunk sewer storage.
Hgal/d x 0 0438,= m3/s
Mgal x 3785 = nT
acre x 0.405 = ha
Operation and maintenance costs have been developed based on the number of
overflow events per year, and on an annual manhour basis [27]. Actual
operation and maintenance costs have been reported at approximately $2000 per
year (ENR 2000) for the West Newell Street installation at Syracuse, New
York [69].
A comparison of costs for various levels of grit removal for the swirl
concentrator/regulator and the helical bend concentrator/regulator is
presented in Figure 50. Swirl design was based on figures generated from
model studies, with ENR 2000 costs applied from Figure 49. Only in cases
where low probability peak flows are being considered should designs based on
80 and 701 grit removal be considered for use [29].
Swirl J)egritter Costs--Swirl degritter construction and operation and
maintenance costs were estimated for units with capacities of 44, 131, and 438
L/s (1, 3, and 10 Mgal/d) and are presented in Table 102 [38]. The estimates
include miscellaneous costs for piping, weirs, plates, and costs for a grit
washer and screw conveyor. Engineering and contingencies are not included.
Operation and maintenance costs include labor, materials and supplies, and
energy costs.
218
-------
400
300
200
» SYIUCUSJ, N T
~ IEST HEIELL STREET [r]
* ESTIVAIEO CONSTRUCTION COSTS ['' D
• ESTIJUTEO CONSTRUCTION COSTS DGJ
I I
P S 10 IS 20 JS 30 35 ,40 43 50 !S SO 55 70
SWIRL TASK DIAMETER, It
H > o 303 .«
Figure 49. Estimated construction cost
for swirl concentrator/regulators (ENR 2000).
50 B
3D
73 100 US
CAPHDITT, ft3/s
I JO
I7» log
f!3/» I 2« 32 - l/i
Figure 50. Comparison of costs for swirl and helical bend
concentrator/regulator for various degrees of grit removal (ENR 2000).
219
-------
TABLE 102. ESTIMATED SWIRL DEGRITTER CONSTRUCTION AND
OPERATION AND MAINTENANCE COSTS3
Annual operation
Swirl degrltter Construction Cost/NgaVd, and maintenance
capacity, Mgal/d cost, $ $/Mga~l-d cost, t/yr
1
3
10
29 100
33 400
40 800
29 100
11 100
4 100
3 600
5 §00
10 600
a. ENR = 2000.
Mgal/d x 0.0«8 » m3/s
Costs of Screening Facilities—Costs of drum screens and microstrainers,
rotary screens, and static screens are based on cost estimates from actual
demonstration scale facilities, and are summarized in Table 103. For several
installations, costs were also estimated for various levels of capacity based
on the configuration of the demonstrated installation. Capital construction
costs for all screening alternatives range from $78 to $166/m3'h {$12 300 to
$26 OOQ/Mgal/d) and average approximately $120/m3-h ($19 000/Mgal/d). The
range of capital cost values generally reflects special construction methods,
type of building, and/or support facilities such as separate pumping stations
or structural and architectural requirements at specific sites. Operation and
maintenance costs average approximately $0.013/m3 ($0.05/1000 gal), and range
from approximately $0.005 to $0.026/m3 ($0,02 to SO.10/1000 gal) for static
screens and all other types of screens.
Costs of Dissolved Air Flotation Facilities—Costs of dissolved air flotation
facilities used for stormwater treatment have varied widely, from
approximately $127 and $165/m3-h ($20 000 and $26 000/Mgal-d) [43, 44], to
over $443/m3-h ($70 QOO/Mgal'd) [45], These differences can be attributed to
special structural and architectural requirements, requirements for
pretreatment, and more importantly, to the design hydraulic loading rate which
can change the cost per design flow capacity by a factor up to 3. For this
reason, costs for dissolved air flotation facilities are presented as a
function of tank surface area as shown in Figure 51. The cost curves
represent data developed for several different sizes of facilities based on
the experienced cost of the demonstration facilities [45], and cost curves
developed from data from dissolved air flotation facilities used in
conventional solids thickening applications [27]. The curves present a range
of cost with the San Francisco data [45] considered on the high side. These
costs, therefore, should be considered as a preliminary guide and should be
followed by detailed cost analysis for specific site applications. Operation
and maintenance costs have ranged from approximately $0,013 to $0.059/nP
($0.05 to %0.22/1000 gal) treated, including pretreatment [43, 44].
Costs of High Rate Filtration—Costs of high rate filtration facilities are
summarized in Table 104 [28J. These costs are based on facilities similarly
designed to that of the Cleveland demonstration project and include a low lift
220
-------
TABLE 103. COST SUMMARY OF SELECTED SCREENING ALTERNATIVES'
Project location
lie) leville,
Ontario [48ja
Cleveland,
Ohio [47jb'c
r i-. Hayne ,
Indiana [50]
Ht Clemens
tlichigan [52]
Philadelphia,
Pennsylvania [55]
Racine,
'rfistcmsin [43]
Seattle, .
Washington [70]
Syracuse,
Hew York [27J-
a, ENR 2000.
b. Estimated costs
Type of screen
Rotary screen
Static screen
Drum screen
Static screen
Drum screen
Rotary screen
Micros trainer
Microstrainer with
chemical addition
Microstrainer
without
chemical addition
Drum screen
Rotary screen
Rotary screen
Drum screen
for several sizes
Screening Annual operation
capacity, Capital Cost, and maintenance
Hgal/d cost, $ S/Mgal d cost, S/1QQQ gal
1 8
5.4
7 2
0 75
5.3
7 5
25
50
100 1
200 3
18
18
38
1 0
7.4
7 4
3 9
25
5
10
of facilities
c Estimates include supplemental pumping stations
33 500
97 700
128 400
14 900
95 600
130 700
608 500
887 800
745 ZOO
340 300
272 400
Z54 30Q
584 700
26 200
90 880
147 900
22 600
600 000
129 500
257 000
.
18 600
17 900
17 800
19 900
18 200
17 400
24 340
17 750
17 450
16 700
15 100
14 100
15 400
26 200
12 270
19 980
5 800
24 000
25 900
25 700
0.083
0 083
0.083
0 042
0 012
0 042
, . . .
0.020
0 039
0.046
0 048
0.049
0.098
and appurtenances.
Mgal/d x 0 0438 = n^/s
V1QOQ gal t. 0 264 = S/m3
221
-------
pumping station, pretreatment by 420 micron drum screens, and chemical
addition facilities [47]. Operation and maintenance costs are based on
300 hours of operation per year.
Costs ofJji gh._Grad_1eirt Magnetic Separation—Costs of high gradient magnetic
separation have been evaluated for a 1.10 m3/s (25 Mgal/d) facility and are
summarized in Table 105 [28]. Capital costs include pretreatment, chemical
addition, thickening and dewatering equipment, pumps, backflush system,
instrumentation, and disinfection system. Operation and maintenance costs
include chemicals, labor, electrical utilities, and maintenance.
Costs of Physica 1/Ch em ica 1 Treatment Systems—Costs of complete
physical/chemical treatment systems including chemical clarification and
chemical recovery, carbon adsorption, and activated carbon regeneration have
been developed [2]. Costs of these facilities for a 1.10 m3/s (25 Mgal/d)
plant range from approximately $4 000 000 to over $50 000 000 or $3 600 000 to
over $45 000 OQO/m3«s ($160 000 to over $2 000 000/Mgal•
-------
10 000
1 ODD
i 00
S/k« FRAHCtSCO, C»
ESTIMATED 90 Mgal/d PHHT.
KUHUIIEE 1ISC [ 44 ]
^
f
i
i
t
- 1
IERI
COST
X
fED
CU
X
.
S
F
RV
r
I
W
,
;HM
ES
i
I
X
•RACINE I1SG FAC1LIT ES.
INCLUDES PRETREkTKENT [
43]
1
1
*
-
I DO
1000 ID 000
DISSOLVED MR FLOTHT10N UNK SURFACE fcREfc, ft2
100 ODD
MOTE. ft t D OB28 - n
>§• i/a * o a 43g - ™/s
Figure 51. Cost of dissolved air flotation facilities.
TABLE 104. SUMMARY OF COSTS FOR DUAL MEDIA HIGH
RATE FILTRATION FACILITIES [47]
25
50
TOO
200
Construction costs,
Construction costs, S/Mgal-d
Operation and maintenance
costs, $
Plant
capacity, .
Mgal/d 24 gal/ft2'rain 16 gal/ft2-imn 24 gal/ft2'imn 16 gal/ft-non 24 gal/ft2 rain 16 gal/ft2'm1n
1 440 000
2 170 000
3 980 000
6 760 000
] 680 000
2 6ZO 000
4 860 000
8 020 000
57 600
43 400
39 800
33 800
67 200
52 400
48 600
40 100
44 000
55 000
98 000
129 000
45 000
57 000
102 000
134 000
a EUR 2000
b. Includes low lift pumping station, prcscreenfgg, and chemical addition facilities; and excludes
engineering and administration.
Mgal/d x 0.0438 = ra3/S
gal/ft^'in1n x 2.445 = mvm min
223
-------
TABLE 105. CONSTRUCTION AND OPERATION AND MAINTENANCE COST FOR A
25 Mgal/d HIGH GRADIENT MAGNETIC SEPARATION INSTALLATION3 [28]
Construction cost
Total, $ 2 113 000
S/Hgal-d 84 500
Operation and
maintenance cost
S/yr 544 000
$/l 000 gal treated 0.12
a. EMR 2000.
Mgal/d x 0.0438 = nP/s
1 000 gal x 3.785 - m3
BIOLOGICAL TREATMENT ALTERNATIVES
Biological treatment is a means of removing organic pollutants from wastewater
streams, and can be accomplished either aerobically or anaerobically. Several
biological processes have been applied to combined sewer overflow treatment,
including: contact stabilization, trickling filters, rotating biological
contactors (RBC), and treatment lagoons [2].
Biological systems must be operated continuously to maintain an active bionass
or be able to borrow the biomass from a system which does operate
continuously. This and the high initial capital costs are serious drawbacks
in utilizing biological systems in stormwater treatment.
Development and testing of new biological treatment processes and further
demonstration of established stormwater biological systems at other locations
have not been attempted beyond the original demonstration facilities.
Complete descriptions, including design criteria, process performance costs,
and facilities descriptions, have previously been evaluated [2]. The
following contains a summary of each process, using updated information and
data, when available, of completed biological facilities.
Install atipns
Descriptions of the biological processes used to control the organic
pollutants found in stormwater are summarized in Table 106. These biological
systems are generally located adjacent to conventional biological facilities
for a source of biomass, with the possible exception of treatment lagoons.
Contact stabilization, trickling filters, and RBCs require supplemental
treatment, usually final clarification, to remove the biological solids
generated by the process. Effluent from treatment lagoons may also require
additional treatment for control of algae or floatable solids. Descriptions
of typical biological treatment installations are summarized in Table 107.
224
-------
COARSE
COMBINED REGULATOR
SED IMEH TATION
DRY WEATHER
FLOK TO
CONVENTIONAL
TREATMENT
EFFLUENT
SCREENING
DISINFEC-
TION
0! SCHARBE j
*!
v STORED RETURN
Figure 52. Typical process flow diagram for sedimentation.
COMB IHED
SEWE8
OKERf LO-K
STORHGI/
DETENTION
C
sc
OAR!
UEN
E
1 HS
F IKE OR
MICRO
SDREEN INS
0 1 SSBL VED
Al R
FLOTATi OK
Bt SiHFEC-
Tl ON
III SCHARBE \
.._... >.
Figure 53. Typical process flow diagram for dissolved air flotation.
HIGH RATE
F1LTRATION (HHF)
COARSE
SEWER
OVERFLOW
STORAGE/
DETENT! OH
I V-
FINE OR
M 1 G SO
SCREEN 1 KG
Figure 54. Typical process flow diagram
for several advanced physical/chemical treatment systems.
225
-------
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Evaluationof Biological Treatment Processes
Biological treatment processes are generally categorized as secondary treat-
ment processes, capable of removing between 70 and 95% of the 6005 and sus-
pended solids from waste flows at dry-weather design flowrates and loadings.
When biological treatment processes are used for stormwater treatment,
removal efficiencies are lower and are controlled to a large degree by
hydraulic and organic loading rates. Most biological systems are extremely
susceptible to overloading conditions and shock loads as compared to physical
treatment processes. However, rotating biological contactors have achieved
high removals at flows 8 to 10 times dry-weather design flows [71].
Biological Treatment Performance—
Typical pollutant removals for contact stabilization, trickling filters, and
RBCs are presented in Table 108, for wet-weather loading conditions. These
processes include primary and final clarification. Final clarification
greatly influences the overall performance of the system by preventing the
carryover of biological solids produced by the processes.
TABLE 108. TYPICAL WET-WEATHER BOD AND SUSPENDED
SOLIDS REMOVALS FOR BIOLOGICAL TREATMENT PROCESSES
Expected range of
pollutant removal, %
Biological treatment process BOD Suspended solids
Contact stabilization 70-90 75-95
Trickling filters 65-85 65-85
Rotating biological contBctcrrsa 40-80 40-80
a. Removal reflects flow ranges from 30 to 10 times dry-
weather flow.
Average pollutant removal by the contact stabilization process at Kenosha,
Wisconsin, is presented in Table 109. Pollutant removal effectiveness was
shown to be directly dependent on the quality of the sludge being produced by
the dry-weather treatment facilities. Dry-weather activated sludge is wasted
to the stabilization tank to provide the biological solids when the contact
stabilization system begins operation. Only after the demonstration system
has operated for many hours will the sludge in the stabilization tank actually
be that produced by the demonstration system and be acclimated to the waste
characteristics of wet-weather flows. The dry-weather treatment plant effi-
ciency was also improved by utilization of the demonstration project final
clarifier during periods when the demonstration facilities were not in use.
Dry-weather plant efficiencies increased from 82 to 94% for BOD, and from 64
to 88% for suspended solids [72].
The plastic media and conventional rock media trickling filters at New Provi-
dence, New Jersey, operate in series during dry weather, and are operated in
parallel during wet weather [73]. When the system is operated in the paral-
lel mode, overall average pollutant removal is decreased and is affected by
the hydraulic flow to the plant, as shown in Figure 55. Overall pollutant
removal also includes both primary and final clarification. It was also
demonstrated that the plastic media filter removed about 2.7 times the BOD as
228
-------
compared to the rock, media filter during wet-weather flows: approximately
0.86 kg BQD/md as compared to 0.32 kg BOD/m3 (54 lb/1000 ft3 versus 20 lb/1000
ft3) at a 45% BOD removal efficiency. A comparison of the BOD removal effi-
ciency as a function of hydraulic and organic loading rates for the rock media
and the plastic media trickling filters is shown in Figure 56.
TABLE 109. AVERAGE POLLUTANT REMOVAL PERFORMED FOR
THE KENOSHA, WISCONSIN, CONTACT STABILIZATION FACILITY [72]
Influent3 Effluentb Removal
Suspended solids, mg/L
Suspended volatile solids, mg/L
Total sol Ids, rag/L
Total volatile solids, mg/L
Total BOO, mg/L
Dissolved BOD, mg/L
COD
Total organic carbon, mg/L
Dissolved organic carbon, mg/L
KjeldaM nitrogen as N, mg/L
Total phosphate as P, mg/L
Total co h forms, MPN/nt
Fecal col i forms, MPN/mL
299
148
685 '
252
H9
31
366
117
29
13,70
4.64
31 038
2 238
23
13
461
130
16
7
66
23
15
7 6
1.8
3 726
443
90.4
90.0
29.2
41.6
84.8
72.1
81.9
76.5
39.7
43.7
58.6
Note: All values indicated are arithmetic mean of 30 runs at
acceptable operating levels except for coliforrns which
are geometric means.
a. Influent samples taken from grit tank effluent.
b. Effluent samples taken prior to chlorination
The demonstration scale RBC at Milwaukee, Wisconsin, confirmed pilot plant
results, handling a higher range of organic and hydraulic loads for periods of
8 to 10 hours [71]. A comparison of organic removal efficiency for both the
pilot plant studies (using raw sewage) and the full-scale wet-weather demon-
stration facilities is shown in Figure 57. It was also shown that as hydrau-
lic residence times fell below about 8 to 10 minutes, the organic removal
efficiency of the demonstration facility dropped significantly. This treat-
ment system was installed as an inline device without final clarification.
Final clarifiers could greatly increase BOD and suspended solids removal by
removing the sloughed biological mass caused by the high hydraulic loadings.
Lagoon Treatment Performance—
Pollutant removal efficiencies by treatment lagoons have varied from highs of
85 to 95% to negative values due to excessive algae production and carryover.
In addition to the type of lagoon and the number of cells in series (stages),
several major factors that influence removal efficiencies include: (1) deten-
tion time, (2) source of oxygen supply, (3) mixing, (4) organic and hydraulic
loading rates, and (5) algae removal mechanisms [2, 52, 74, 75].
A single cell storage/oxidation lagoon in Springfield, Illinois, averaged 27%
BOD removal and 20% suspended solids removal; however, fish kills in the
229
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receiving water were greatly reduced as compared to that prior to the con-
struction of the facility [75]. Multiple cell facilities with algae control
systems constructed at Mount Clemens, Michigan and Shelbyville, Illinois
provide 75 to 90% suspended solids and BOD removal efficiencies during wet-
weather conditions [52, 74].
too c-
80
40 -
(fi
a
C/J
20
-AVERAGE
DRY-*i»iTH
CONDITIONS
V SUSPENDED SOLIDS
* BOD
_L
_L
_L
Mga l/d x 0 0438 = oi3/s
345
PLANT FLOi, Mga!/d
Figure 55. Overall trickling filter performance as a function of hydraulic
flow, New Providence, New Jersey [73].
100
80
20
DOCK MEDIA
FI11ER
PLASTIC MEDU
l I.TEB
* ORGANIC LOAD
HYDRAULIC LOAD
HYORAULt C
LOADING
HKORAULIC
LCADlNG
20
40
GO
80
1 00
1 20
1 4D
I BO
HYDRAULIC LOADING RATE, Mgal/acra -d
lb/1000
ORGANIC LOA01NO RATE,
Hgal/aore - d x 0 0389 - n3/ra2-h
Ib/1000 ft3 x 0 0130 - kg/m3
Figure 56. Comparison of rock media and plastic media trick!im
filters as a function of hydraulic and organic loading rates [73'
230
-------
OlKONSmtlOH
FUCiLJTES ,
TESTS
"r
it «B tg 100
Iti/lDOO II* • d i 4 SB2 i I0'3=kj
Figure 57. Comparison of COD removal performance for pilot and full
scale demonstration RBC facilities, Milwaukee, Wisconsin [71].
Process efficiency profiles for suspended solids and BOD at the Mount Clemens
demonstration facility are shown in Figure 58, for a 3-stage lagoon system
with a microstrainer and sand filtration for suspended solids, BOD, and algae
control. It was determined that intermediate algae control had little effect
on the overall treatment performance [52].
Operational Problems—
An operational problem common to all stormwater biological systems is that of
maintaining a viable biomass to treat flows during wet-weather conditions.
For processes that borrow biomass from dry-weather facilities or allow the
biomass to develop, a lag in process efficiency may be experienced as the
biomass becomes acclimated to the changing waste strength and flowrate. In
addition to maintaining a biological medium, clarification and/or storage are
often required to provide operational control of the process, and can greatly
increase capital costs of the facility.
General maintenance problems experienced by wet-weather biological facilities
are similar to those experienced at conventional biological installations.
Winter operation of mechanical surface aerators have had some serious
drawbacks, including icing, tipping, or sinking [52, 72]. Other methods of
providing the required oxygen that show promise and have been demonstrated at
many dry-weather facilities include diffused air systems and submerged tube
aerators [2].
At Mount Clemens, Michigan, operational problems included sludge buildup in
the first cell of the lagoon system and algae control [52].
231
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232
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Design Criteria—
The principal design criteria used to evaluate and design biological systems
generally include hydraulic and organic loading rates, sludge and hydraulic
detention times, and in the case of contact stabilization, such factors as F/M
ratio, mass of organisms in the system, and rate of substrate utilization.
At Kenosha, yisconsin, several process criteria were correlated with effluent
BOD and suspended solids concentrations and removal efficiencies. The results
of this correlation are presented in Table 110 [72]. These tests also
indicated that low MLSS concentration of less than 2100 mg/L and high
reaeration times of greater than 4 hours and long stabilization periods may
seriously affect process efficiency. A contact time of at least 10 minutes
was also found for satisfactory operation and performance of the facilities.
TABLE 110. RESULTS OF CORRELATION OF CONTACT STABILIZATION PROCESS
PERFORMANCE AND PROCESS PARAMETERS AT KENOSHA, WISCONSIN [72]
Multiple correlation
Process equation coefficient
Effluent BOO concentration, mg/L = 1 6 (A) + (1 92 W + 9.1 0 670
Effluent SS concentration, mg/L = 2 43 (C) * 1 83 (A) + 13.9 0-541
BOD removal, " = 0-081 (D) - 1 0 (B) - 1.3 {A) + 80 6 0 745
SS removal, ' = 0.02 (E) - 0 97 (C) - 0 7 (A) + 87 1 0.691
Note- A = F/M ratio
D = Stabilization time, d
C = Reaeration time, h
D = Influent BOD concentration, mg/L
E = Influent SS concentration, mg/L
Typical design criteria for biological treatment systems have been previously
presented and discussed in the literature [2] and are summarized in Tables
111 through 114. Design criteria for treatment lagoons are not based on
biological kinetic theory, but rather on actual practice and experience. An
inventory and operational data from municipal lagoon facilities have been
collected for various types of lagoons for each region in the United States
[76], Factors affecting lagoon performance, including organic and hydraulic
loading, odor and aesthetic failures, wind, light, and mixing, are evaluated.
233
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TABLE 111. OPERATIONAL AND DESIGN PARAMETERS FOR THE CONTACT
STABILIZATION FACILITY AT KENOSHA, WISCONSIN [72]
Parameter
Average
veluea
Ringe of .
values tested
HLSS concentration, mg/l 3 400
F/H ratio in contact tank,
Ib BOD5/lb MLSS-d 2 8
Sludge retention time, d 2.3
BOD loading rate,
Ib BOD5/1 000 ft3-d 500
Detention time, h
Contact tank 0.25
Reaeratlon time 3.0
Recycle ratio, Qr/Q 0.40
Volume of air supplied 1n
contact tank, ft3/1b BODg 250
1 000-5 600
0.5-5.0
0-7.0
200-1 000
0.17-0.33
1.0-10.0
0.20-0,60
100-700
a. Based on 30 optimized runs.
b Ranges based on 49 runs.
Ib BOD5/lb HLSS d = kg BODg/kg MLSS-d
Ib 6QQ5/1 000 ft3-d. x 0 016 = kg ""
ftVlb B005 x 62.4 • L/kg B00g
TABLE 112. DESIGN CRITERIA FOR TRICKLING FILTERS OPERATED IN
PARALLEL FOR CONTROL OF WET-WEATHER FLOWS [2, 73]
Parameter
Filter media
Hydraulic loading rate, M|al/acre d
Recommended design
Rjnge
Organic loading rate, Ib BODg/1 000
Recommended design
Range
Depth, ft
Recirtulation ratio, Qr.Q
a. Or redwood slats
b Ultra-high rate trickling filter
High rate Ultra-high rate
Rock
20
10-40
ft3
40
20-115
3-8
1:1-4-1
depth at itew
Plastic8
70
40-120
85
45-230
20-40b
1:1-4:1
Providence, Hew
Jersey = 14.4 ft.
Mgal/acre-d x 0.039 = ra^/m2 h
Ib BODs/l 000 ft3 d x 0.016 » kg BODs/mJ-d
ft x 0.305 = m
234
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TABLE 113, COMPARISON OF DRY-WEATHER AND WET-WEATHER DESIGN
PARAMETERS FOR ROTATING BIOLOGICAL CONTACTORS
Parameter
Range of general
dry-weather
values [2]
Milwaukee, Wisconsin [71]
Dry-weather
design
Het-weather
range
Hydraulic loading rate,
gal/ft2-da 2-8
Organic loading rate,
Ib BOD5/1 000 ftZ-d 5-15
Detention time, nrfn 15-20
a. Cased on disc surface area
b, Based on correlation of COD:BOD ratios.
gal/ftz-d x 1.698 = _,
Ib eOD5/1000 ft2'd x 4.882 x 10" 3 = kg
25-35
5,40
69
30-70b
10-20
TABLE 114, COMPARISON QF DESIGN CRITERIA FOR
TREATMENT LAGOONS [2]
Aerated lagoons
Organic loading rate,
Ib BODr/acre-d
No. of lagoons
Depth, ft
Detention time, d
Oxidation
lagoons
20-50
2-6
2-5
30-160
Aerated oxidation
lagoon
100-500
2-6
6-10
5-11
Complete mix
aerated lagoon
500-1 000
1-4
10-15
1-8
Facultative
lagoons
15-80
2-10
6-12
7-12Q3
a. Use of mechanical surface aerators reduces detentions to approximately 7-10 days.
Ib BODq/acre d x 1.1208 = kg BOD,/ha-d
ft x 07305 = m s
Costs of Biological Treatment Facilities--
A comparison of construction, and operation and maintenance costs for
biological treatment systems and treatment lagoons is presented in Table 115.
Costs of final clarification are included where control of solids and sludge
produced by the biological treatment system are required. Costs also include
pumping, disinfection, and algae control systems when applicable.
Engineering, administration, and land costs are not included in the estimates;
however, land costs may be the controlling economic factor in the evaluation
of lagoon treatment systems and therefore must be evaluated for each specific
locations.
Many biological treatment systems are integrated with or are a part of dry-
weather treatment facilities. Cost estimates of the wet-weather portion of
these facilities were separated from total costs of the total treatment
235
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TABLE 115. SUMMARY OF CAPITAL AND OPERATION AMD MAINTENANCE
COSTS FOR BIOLOGICAL TREATMENT ALTERNATIVES3
Project location
Wisconsin [72]
Milwaukee,
HI icons In
[2. 71 P
Itount Clemens,
Michigan [52J
Demons trail on
syste»
CUywIde
system
New Providence,
New Jersey
[2, 73F
Illinois [zi 74]
Southeast
site
SouUmest
site
Springfield,
Illinois [2, 75]
Ppafc Cost/ Annual operation
Type of plant Cost/ tributary and maintenance
biological capacity, Construction capacity, area, cost, t/1 000 gal
treatment Hgal/d cost, $ $/HgaI-d $/«cre (except as noted)
Contact 20 1 364 000 68 200 1 140 13 a
stabilization
Rotating 4.3 299 OOD 69 ZOO 8 540 4 4
biological
contactor
Aerated 64 642 700 10 000 3 030 20 0
treatment lagoons
Storage/aerated 260 S 737 000 22 000 3 900 19.0
treatment lagoons
High-rate 6 475 000 79 150 . .. 12 3
trickling filter
Oxidation lagoon 28 43 400 1 550 t 000 $1 530/yrd
Storage and facul- 110 337 700 3 070 750 $5 780/yrd
tatlve lagoons
Oxidation lagoon 67 176 000 2 600 80 $2 100/yr
a, EKR 2000.
b Includes estimate of final elaHflar.
c Includes plastic media trickling filter, final clarifier, plus one-half of other costs.
d Based on estimated nan-day labor requirements.
Hgal/d x 0 0438 •= n3/s
acres x 0.405 - ha
in 000 gal x 0 264 • t/n3
systems. The cost of the inline RBC at Milwaukee, Wisconsin, was used
together with an estimated cost for a final clarifier to develop an estimated
cost of a complete RBC treatment system [71]. The final clarifier cost was
based on one 19.8 m (65 ft) diameter clarifier with a surface loading rate of
2.04 m3/m2-h (1200 gal/ft2-d).
Costs of lagoon treatment systems vary widely, and are a function of the type
of lagoon (oxidation, aerated, or facultative); the number of cells; and the
miscellaneous equipment requirements including: aeration equipment,
disinfection equipment, instrumentation, pumping, and algae control
provisions.
Costs for many of these stormwater facilities are based on only one
installation of each biological treatment process. Therefore, these costs
should be considered only coarse estimates and may be greatly influenced by
the degree of integration with dry-weather treatment required to produce a
viable system. These costs can be used as a preliminary guide, but detailed
analysis should be performed to compare and evaluate biological treatment
alternatives with other methods of treatment and control.
236
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Biological Treatment Systems
Both single purpose and dual use (integrated biological treatment) facilities
have been demonstrated in controlling combined sewer overflows. Single
purpose facilities treat flows only during wet-weather conditions as in the
case of the contact stabilization installation and several lagoon
installations [52, 72, 75]. However, the clarifier of the contact
stabilization facilities is also used for dry weather final clarification
[72]. Dual use or integrated facilities are capable of treating both dry- and
wet-weather flows.
Dual use has been accomplished by changing modes of operation during wet
weather as demonstrated at New Providence, New Jersey. Increased performance
during dry-weather was also obtained by using the trickling filters in series
[73]. Biological systems have also been used to treat dry- and wet-weather
flows without process modification by pushing the system to design limits as
hydraulic and pollutant loads increase. Examples include the inline RBC unit
at Milwaukee, Wisconsin, and the Southwest lagoon treatment system at
Shelbyville, Illinois [71, 74]. At Ft. Wayne, Indiana, an existing terminal
lagoon is used by both the dry-weather treatment facilities and the wet-
weather screening installation prior to discharge to the receiving water
[50].
Because of the limited ability of biological systems to handle fluctuating and
high hydraulic shock loads, storage/detention facilities preceding the
biological processes may be required. Storage/detention will be used at the
citywide lagoon treatment facilities under construction at Mount Clemens,
Michigan [52]. The storage unit will reduce the maximum flows entering the
system from 11.39 m3/s (260 Mgal/d) to a design flowrate of approximately 0.18
flp/s (4.0 Mgal/d) through the lagoon system. A similar concept is also used
at the Southwest treatment site in Shelbyville, Illinois [74].
Initial capital investments of integrated or dual use facilities can be
reduced by apportioning part of the costs to the dry-weather facility. The
cost reduction is in proportion to the net benefit that the wet-weather
facility provides to the overall treatment efficiency during dry-weather
periods. A description of this evaluation is presented in Section 4.
LAND TREATMENT OF STORMUATER
Land treatment methods have been used successfully to treat municipal and some
kinds of industrial wastes for several years. The use of land treatment in
treating wastewater or stormwater is usually limited by hydraulic application
rates and the resulting land area requirements. Since stormwater volumes can
be many times larger than dry-weather municipal wastewater flows, application
rates are proportionally more critical in determining the economic feasibility
of their application to stormwater treatment. Unless adequate flow
equalization could be provided, slow rate land treatment processes with low
application rates would require excessive land area.
237
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Process Description jand Facilities Installations
Based on the limitations of application rates and land area only, the
following land application processes appear to have promise for treating
stormwater runoff:
• Wetlands
* Rapid infiltration
* Overland flow
These methods should have application for stormwater treatment despite the
absence of conclusive design, operating, and performance data from operational
projects.
Wetlands—
Wetlands are areas with too many plants and too little water to be called
lakes, yet they have enough water to prevent most agricultural or
silvicultural uses. Existing wetlands areas are generally large enough to
accommodate expected stormwater runoff volumes and their ability to influence
stormwater quality appears to hold promise.
The Wayzata, Minnesota [77], project is one of the few projects currently
investigating the potential of wetlands treatment, but any conclusions
regarding expected quality will require more data. However, results from
wetlands projects researching the potential for renovating municipal
wastewater indicate effective treatment does take place [78], The management
technique for nutrient removal, loading rates, and the suitable site
characteristics need further study. Winter application in northern latitudes
may not be feasible.
Rapid Infiltration—
in rapid infiltration, most of the applied wastewater percolates through the
soil, eventually reaching the groundwater. Rapidly permeable soils such as
sands and loamy sand are suited to this process. The high application rates
preclude consumptive use by plants (vegetative covers are not normally used)
and there is little evaporation. Return of renovated water to the surface by
wells, underdrains, or groundwater interception may be necessary or may be an
advantage depending on existing groundwater quality reuse potential or water
rights considerations. Rapid infiltration is only affected by the most severe
climatic conditions and will require a relatively small amount of land if soil
conditions are correct. Surface clogging due to high suspended solids loading
can reduce infiltration rates and may require pretreatment.
Overland Flow--
In overland flow treatment, water flows across a vegetative surface to runoff
collection ditches for reuse or discharge to surface water. Treatment is by
238
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physical, chemical, and biological means as a thin film of water flows over
the relatively impermeable surface; very little percolation takes place,
Land Application Projects--
The only actual stormwater land treatment projects discovered in the
literature are a pilot scale wetlands treatment system in Wayzata,
Minnesota [77], and aa experimental scale project in Tucson, Arizona [79],
which combined the rapid infiltration and overland flow methods. Features of
these projects are shown in Table 116.
TABLE 116. DESCRIPTION OF STORMWATER TREATMENT
PROJECTS USING LAND TREATMENT
Item
Wayzata, Minnesota [77]
Tycson, Arizona [79]
Type of treatment
Hydraulic loading,
Mgal/acre-yr
Land area, acres
Period of operation
Preappllcation
treatment
Vegetative cover
Surface Influent and
effluent nxmftoring
Groundwater
monitoring
Management techniques
Wetlands
"-Z,4a
7.5
November 1974 to present
Gravel roughing filter
Harsh vegetation
Yes
Observation wells and
lystmeter pans
Intermittent application,
dewatertng, recirculation,
and comparison with unmanaged
control rnarsn
Overland flow, rapid infiltration
140-880
0.02
Four trials, fall 1971
None
Turf grass
Yes
Subsurface flow collected by
underdrain for monitoring
Four separate trials monitored
changes in surface and subsurface
outflow quality with respect to
time
a. Hydraulic loading Includes surface runoff (1.12), precipitation (0.83), and
groundwater Infiltration (0.42).
"Igal/acre-yr x 9 353 6 = nrVha-yr
acre x 0 405 = ha
These projects indicate that significant renovation is taking place, but more
data are needed to support any conclusions on expected quality of the treated
storrawater, pretreatment requirements, marsh fill-in, vegetation maintenance
and control, and associated costs.
Evaluation of Land Treatment_Alternatives
Although limited data have been compiled, an evaluation of the various land
treatment alternatives using available data from stormwater treatment projects
239
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and municipal dry-weather flow projects is presented for pollutant removal
efficiencies, design criteria, and costs.
Process Evaluation--
Results comparing treatment of domestic wastewater by natural and artificial
marshes indicated that significant pollutant removals take place in each
case [80]. It was determined that artificial marshes acted similar to
natural marshes, but treatment efficiency was better for managed artificial
systems. Removals were related to detention time and the length of marsh
through which the wastewater passed. Treatment efficiency was adversely
affected by climatic conditions; poor pollutant removals associated with the
first heavy frost of the fall were observed. The best seasonal removals
averaged approximately 29% for BOD and 13% for phosphorus for natural marshes.
The managed artificial marsh averaged approximately 90% for BOD and 64% for
phosphorus. Marsh systems can handle the high solids loading associated with
stormwater runoff, and management techniques to increase pollutant removals
are available.
Studies using marsh systems for stormwater treatment also indicate significant
pollutant removalss as summarized in Table 117.
TABLE 117. TYPICAL POLLUTANT LOADING AND
REMOVAL RESULTS USING LAND TREATMENT
Wayzata, Minnesota [77]
Pollutant
loading, lb/acre-yr Removal, %
Tucson, Arizona [79]
Suspended so) Ids
4,973
94 Results indicated significant
pollutant removal » but loading
Phosphorus
Anmoma-mtrogen3
17. B
64,8
78 and percent
determined.
0
removals were not
a Ammonia concentrations in groundwater are higher than the stormwater Influent,
Ib/acre-yr x 1.121 = kg/ha-yr
Limited studies using stormwater runoff and rapid infiltration indicate good
treatment performance, however, actual percent removals were not
determined J79], Several conclusions can be made from results using sanitary
wastewaters:
* Pollutant removals by the filtering and straining action of the soil
are excellent.
* Suspended solids, BOD, and fecal coliforms are almost completely
removed.
» Nitrogen removals are generally poor unless specific operating
procedures are established to maximize denftrification.
240
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Total nitrogen removals range from 30%, without demtrification procedures, to
50% if steps to maximize denitrification are taken. Phosphorus removals can
range from 70 to 90% depending on the physical and chemical characteristics of
the soil.
Overland flow systems can achieve treatment to secondary level (or better)
from raw, primary and treated, or lagoon treated municipal wastewater.
Nitrogen and BOD removals are comparable to conventional advanced wastewater
treatment. Nitrogen removals usually range from 75 to BQ% with runoff
nitrogen being mostly in the nitrate form. Nitrogen removal can be affected
by cold weather as a result of decreased plant uptake and reduced biological
activity. Phosphorus removals by adsorption ana precipitation are limited
because of incomplete contact between the wastewater and the adsorption sites
within the soil; removals usually range from 30 to 6Q% on a concentration
basis.
Design Criteria—
Applying alternative land treatment methods to stormwater treatment will be
affected to different degrees by climatic restrictions, constituent and
hydraulic loading to the system (i.e., preapplication treatment), site
characteristics, and vegetative cover. Typical design features for the
various processes, based on treatment of municipal wastewater, are compared in
Table 118. The major site characteristics are compared for each land
treatment process in Table 119.
The nitrogen, phosphorus, suspended solids, and BOD loading capacity will vary
for each land treatment process depending on such factors as preapplication
treatment, expected treatment performance, hydraulic limitation of the soil
and underlying geology, nitrogen removal capacity of the soil-vegetation
complex, and discharge standards.
For rapid infiltration systems, the infiltration capacity of the soil could be
limited by excessive suspended solids loadings. If rapid infiltration is
used, it is recommended that stormwater suspended solids concentrations be
consistent with that of primary treated municipal effluent before application
to the land. Nitrogen loading is often the limiting criterion for percolating
water from rapid infiltration systems to meet EPA drinking water standards of
10 mg/L for nitrate-nitrogen. Crop uptake of nitrogen, denitrification, and
storage in the soil will all affect the maximum allowable loading. Other
loading parameters may include phosphorus and heavy metals.
For overland flow systems, treatment performance is directly related to
pollutant loadings and hydraulic application rates. The general pollutant
loading capacity depends primarily on the expected treatment performance and
the level of preapplication treatment. Suspended solids reductions to a level
consistent with municipal wastewater that has been screened and possibly
degritted and degreased would be desirable to ensure successful operation of
the system. Methods for distribution of stormwater runoff with high suspended
solids loads will require careful consideration. Because application rates
partially govern the expected effluent quality, maximum allowable application
241
-------
rates during precipitation may be relatively low. As a result, significant
storage may be required affecting the economic feasibility of this process.
TABLE 118. COMPARISON OF DESIGN FEATURES FOR
LAND TREATMENT PROCESSES [78]
Feature
Application techniques
Annual application
rate, ft/yr
Field area required,
acres3
Typical weekly appll-
Wetlands
Sprinkler or
surface
4 to 100
11 to 280
1 to 25
Application process
Rapid infiltration
Usually surface
20 to 560
2 to 56
4 to 120
Overland flow
Sprinkler or
surface
10 to 70
16 to 110
2.5 to 16
cation rate, 1n./wk
Minimum preappli cation
treatment provided 1n
United States
Primary treatment Primary Screening and
or coarse sedimentation grit removal
filtration
Disposition of
applied wastewater
Need for vegetation
Evapotranspiratlon, Mainly
percolation, and percolation
runoff
Requi red
Optional
Surface runoff and
evapotransplratjon
with some percolation
Required
a. Field area 1n acres
(43.8 L/s) flow.
ft/yr x 0.3048 » m/yr
acres x 0.405 = ha
in./wk x 2.54 = cm/wk
not including buffer area, roads, or ditches for a 1 Mgal/d
TABLE 119. COMPARISON OF SITE CHARACTERISTICS FOR
LAND TREATMENT PROCESSES [78]
Application process
Characteristics
Wetlands
Rapid Infiltration
Overland flow
Slops
Soil permeability
Depth to
groundwater
Climatic
restrict tons
Usually less Not critical, excessive Finish slopes
than SX slopes require much 2 to 8?
tarUworS
Slow to
aoderate
Rapid (sands, \oasy
sands)
Slow (clays, silts,
and soils with
larperroeable barriers)
Wot criticil 10 ft Iles'er depths Not critical
(zaro) are acceptable where
underdraliwg* 1s
provided)
Storage lay Hone (possibly modify Storage often needed
be neeetei) for operation in cold for cold weather
cold (feather weather)
ft x 0,3MB - n
242
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Costs of Land Treatment Systems--
There is an absence of full scale operational projects where capital and
operating costs have been compiled. However, cost curves for rapid
infiltration and overland flow systems which treat municipal wastewater have
been compiled presenting component capital and operating costs [81].
The use of existing wetlands already influenced by stormwater would appear to
be very economical but existing sites are not always available. Creation of
artificial wetlands is another approach which has received some attention as a
low cost land treatment method.
DISINFECTION
Disinfection of storm and combined sewer overflows is generally practiced at
all stormwater treatment facilities to control pathogens and other
microorganisms in receiving waters. At most stormwater installations,
disinfection has been accomplished by applying conventional wastewater
technology supplemented by high rate processes and on-site generation of
disinfectant. Several aspects of disinfection practices require
reconsideration for stormwater treatment applications. These include:
• A residual disinfecting capability may not be feasible for
stormwater discharges. Recent work indicates that chlorine
residuals and compounds discharged to natural waters may be harmful
to aquatic life.
• The coliform count is increased by surface runoff in quantities
unrelated to pathogenic organism concentration. Total coliform
levels may not be the most useful indication of disinfection
requirements and efficiencies.
* Discharge points requiring disinfection are often at outlying points
on the sewer system and require unmanned, automated installations.
* Storm flow is highly variable both in quantity and quality;
disinfection facilities must be able to meet these fluctuations.
Three basic needs for control of microorganisms in stormwater overflows have
been identified [82]: (1) to obtain knowledge of the storm flow's
microorganism pathogenic quality and the pathogens' relationships to other
indicator organisms; (2) to develop high-rate disinfection systems to reduce
large tankage and/or dosage requirements, and (3) to develop disinfection
facility design and operation techniques for the highly varying quality and
quantity characteristics of storm flows.
Disinfection Projects
Demonstration projects evaluating stormwater disinfection technology are
summarized in Table 120. Other projects, evaluating the characteristics and
impacts of microorganisms in stormwater, have been beneficial in providing a
background understanding of the sources and constituents of microbial
contamination in overflows [82-85].
243
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TABLE 120. SUMMARY OF DEMONSTRATION
STORMWATER DISINFECTION PROJECTS
Project location
Disinfectant
agent
Source Description of disinfection system
Period of
operation
Boston,
Massachusetts [17]
Cottage Farm
Detention and
Chlorination
Station
Cleveland,
Ohio [06]
Fitchburg,
Massachusetts [87]
New Orleans,
Louisiana [88]
New York City,
New York [25]
Spring Creek
Philadelphia,
Pennsylvania
[55, 56, 57]
Sodium hypo-
chlonte
{NaOCl)
Sodium hypo-
chlorite
(NaOCl)
Sodium hypo-
chlorite
(NaOCl)
Sodium nypo-
chlorite
(KaOCl)
Sodium hypo-
chlorite
(NaOCl)
Sodium hypo-
chlorfte
(NaOC.1)
Ozone (03)
Purchased/ Automatic disinfection system injects
stored up to 3 000 gal of 10 to 15* NaOCl
into the influent channel to the
detention basins for the design storm.
Purchased/ Disinfection of two bathing beaches
stored enclosed by fabric barriers and dis-
infection of polluted streams and
overflow points influent to Lake Erie,
Purchased/ High-rate application of disinfectant
stored via thin film In a Dynactor. System
incorporates chemically assisted
high-rate settling.
Central NaOCl is generated at a central manu-
generation facturing facility with a capacity
of 1 000 gal/h. The 12% NaOCl is
transported and stored at 4 pumping
stations on 3 overflow channels to
disinfect pumped stormwater.
Purchased/ Automatic disinfection system injects
stored up to 60 000 Ib/d of 52 NaOCl into
the inlet sewer of the storage/
detention facilities.
Purchased
On-site
generation
Comparison of two disinfectants on
screened and unscreened combined
sewer overflow. Short contact
times are achieved by high velocity
gradients in a plug flow contact
Chamber regime.
1971 to present
1968 to 1970
1974 to present
1972 to present
1972 to present
1959 to 1973
Rochester,
New York [36]
Syracuse,
New York [35, 89]
Chlorine (Clg) Purchased
Chlorine
dioxide (C1Q2)
Chlorine gas
(C12)
Chlorine
dioxide (ClOg)
On-site
generation
Purchased
On-site
generation
Sequential addition of Cl2 and C102 1975 to 1976
with flash mixing at each point of
application. Disinfection is final
treatment step following sedimentation,
storage, dual media filtration, and
carbon column pilot facilities.
Evaluation of individual and sequential 1974 to present
addition of Cl2 and ClOg following
treatment of combined sewer overflows
by screening and swirl concentration.
gal x 3.785 = L
Ib/d x 0.454 = kg
244
-------
The Fitchburg, Massachusetts, demonstration facility represents a new
technology in disinfectant application [87, 90]. The 373 m3/d (100 000
gal/d) combined sewer treatment facility includes chemical addition (FeCl3,
CaO, and polymer) and high-rate settling prior to disinfection.
Disinfection is accomplished by the use of thin film technology. Hypochlonte
is sprayed on a thin film of wastewater to provide maximum instantaneous
contact and eliminate the need for further mixing, A small sump is provided
at the outlet of the unit but no contact chamber is required. Analysis
indicates that both total coliform and fecal coliform are reduced to less than
36 organisms per 100 ml.
A second high-rate settling unit after disinfection was found to add little to
the overall suspended solids removal efficiency. Typical pollutant removals
for the facility average 651 for BOD and COD, 85% for suspended solids, 90S
for total phosphorus, and over 99S for total and fecal coliforms.
Future studies proposed at Fitchburg will include the use of ozone as a
disinfecting agent.
Disinfection Agents
The disinfection agents used in wastewater and stormwater treatment include
chlorine, calcium and soaiun hypochlorite, chlorine dioxide, and ozone.
Results from combined bench and pilot plant testing of high gradient magnetic
separators indicate 99.9% removal of viruses and over 99% removal of total and
fecal coliforms [28], However, physical methods and other chemical agents
have not experienced wide usage either because of excessive costs or
difficulties with application technology.
Evaluation of Disinfection Agents—
The four potential disinfection agents have some comnon characteristics; all
are oxidizing agents, corrosive to equipment, and are highly toxic to both
microorganisms and higher life. Other characteristics and differences that
should be considered when choosing a stormwater disinfectant are summarized in
Table 121. A discussion of these characteristics follows.
Stability--The more stable chemicals allow the designer greater flexibility in
developing a treatment facility. Chlorine gas is always purchased and its
high degree of stability allows long storage periods. Hypochlorite can be
purchased or generated onsite and can be stored for several months, or it can
be generated at a steady rate and stored between overflow events. Peak demand
requirements can come from storage or be purchased as needed.
At New York's Spring Creek facility, purchased sodium hypochlorite is diluted
and stored at a strength of about 5% available chlorine, which reduces the
rate of deterioration [25]. It has. been shown that the stability of sodium
hypochlorite is higher at reduced concentrations [2]. Chlorine dioxide and
ozone are the least flexible; they must be generated onsite and their
245
-------
effective lives are too short to make storage practical. Consequently,
disinfectant generating capacity must be sufficient to handle anticipated peak
demands.
TABLE 121. CHARACTERISTICS OF PRINCIPAL STQRMWATER
DISINFECTION AGENTS
Characteristic
Stability
Reacts witn diimorna
Chlorine
Stable
Yes
Hypochlonte
6 month half-life
Yes
Chlorine
dioxide
Unstable
No
Ozone
Unstable
No
to form chloramines
Liestroys phenols
At Ingh At High
concentrations concentrations
Yes
Yes
Produces d residua) Yes
Yes
Affected by pH
Hazards
llore effective More effective
at pil<7.b at pH
-------
Hazards—Chlorine, chlorine dioxide, and ozone are all dangerous gases that
must be carefully handled by competent personnel. The hazards of chlorine gas
are well known and have caused restrictions of its use or transport in several
cities including Hew York and Chicago. Gas concentrations as low as 5 ppm can
cause difficulty in breathing and 1000 ppm can be toxic. Chlorine dioxide has
toxicities similar to chlorine gas ana the additional danger of exploding with
any slight change in environment. It must be kept in the aqueous state to
minimize dangers. The gas is soluble in water but does not react chemically
with water. Ozone's oxidizing capacity makes concentrations of 1.0 ppm in the
atmosphere hazardous to health. Hypochlorite can be obtained as a solid or
liquid and does not have the potential dangers of the other three agents. It
is the safest choice for remote, unmanned disinfection operations.
Evaluation of Application Technology--
Several studies have been conducted to examine application techniques that
improve or enhance the disinfecting capability. Adequate mixing under plug
flow conditions and sequential addition of chlorine (CIO and chlorine dioxide
(C10j>) were two significant parameters which Influenced disinfection
efficiency.
Mixing—In high-rate disinfection systems where contact times are less than 10
minutes, usually in the range of 1 to 5 minutes, adequate mixing is a critical
parameter, providing complete dispersion of the disinfectant and forcing
disinfectant contact with the maximum number of .mcroorganisms. The more
physical collisions high-intensity mixing causes, the lower the contact time
requirements, fixing can be accomplished by mechanical flash mixers at the
point of disinfectant addition and at intermittent points, or by specially
designed contact chambers, or both [2, 36, 55].
At Philadelphia [55, 57], a specially designed contact chamber with closely
spaced corregated baffles was used to increase the velocity gradient
(G) in t~<. G is a function of the viscosity of the fluid, velocity, and
headloss. In this application it was considered desirable to keep the pro-
duct of G and detention time (t) a constant, at less than peak design flow
conditions. Assuming that t remains constant, therefore velocity remains
constant, G is increased by increasing the headloss through the use of
corregated channels [2]. Spacing and arrangement of the channels is also
essential to maintain plug flow conditions preventing any backmixing of the
dispersed disinfectant. Using this design, a contact time of 3 minutes with
initial chlorine concentrations as low as 2.6 mg/U reductions of total and
fecal coliforms by 99.91 were obtained.
At an experiment at Fort George fteade to show the effect of mixing on
disinfection, turbulence was created in a sewage effluent line by installing a
20.3 cm (8 in.) orifice to increase flow velocities to the range of 2 to 2.3
m/s (6.6 to 7.6 ft/s). Virus kills were increased to 83.b to 99.3% from 45.8
to 73.5%; however, it was found that coliform kills did not substantially
increase [91].
Sequential Addition of Disinfectants—Disinfection was shown to be enhanced
beyond the expected additive effect by sequential addition of CU followed by
247
-------
C1Q2 at intervals of 15 to 30 seconds [36, 82, 89]. A minimum effective
combination of 8 mg/L of Cl2 followed by 2 mg/L of C102 was found as effective
as adding 25 mg/L Cl£ or 12 mg/L C1Q2 individually in reducing total and fecal
coliforms, fecal streptococci, and viruses to acceptable target levels [82,89].
It was surmised that the presence of free C"\2 "In solution with chlorite ions
(C102), (the oxidized state of C1Q2), may cause the reduction of ClOi back to
its original state. This process would prolong the existence of C1Q2» the
more potent disinfectant [82, 89].
Other significant findings of the Onondaga County, New York, studies include
the following:
» Sequential doses of the same disinfectant do not increase
disinfection over a single dose with the same total quanity.
* Prescreening does not appear to affect Cl, disinfection but slightly
improves disinfection with ClOp.
t Cl2 and ClO^ demands may be due to different materials in
wastewater.
* The maximum antiviral activity of C10? was found to occur between pH
4.5 and 7.5.
• Increases of temperature from 2°C to 30°C (36° to 86°F) slightly
improved high-rate bacterial disinfection with both Cl2 and CIO?-
Viral inactivation with C102 was sharply decreased at 4°C (39°F) but
unaffected between 12°C and 36°C (54°F and 97°F).
Aftergrowth of Microorganisms
Aftergrowth of indicator microorganisms in stormwater after disinfection have
been reported [84, 86, 89]. Indicator microorganisms, specifically total
coliforms, enter a log growth phase when the disinfectant residual decreases
to undetectable values. Aftergrowth coliform levels can exceed before
disinfection background levels. Total and fecal coliform aftergrowth were
reported during stream and laboratory studies at Cleveland, Ohio [86]. Only
total coliform aftergrowth was reported during a stormwater disinfection study
at The Woodlands, Texas [84]. In both cases, aftergrowth of fecal
streptococci did not occur. Laboratory aftergrowth studies in Syracuse, New
York, revealed that difficulties in simulating the conditions for aftergrowth
may be encountered for bench scale tests [89]. Aftergrowth tests, conducted
to determine the ultimate bacterial and viral counts that might result in the
receiving water from the discharge of untreated and disinfected combined sewer
overflow, showed no measurable increases during and up to 3 days. These
results were felt to be more indicative of the inability to simulate receiving
water conditions in the laboratory rather than a lack of aftergrowth.
A possible chemical change in the composition of the stormwater caused by
chlorine may enhance aftergrowth. This chemical change is assumed to be a
cleavage of large protein molecules into smaller proteins, peptides, and ami no
248
-------
acids. These smaller molecules are more readily available to the bacteria for
growth and reproduction than the larger proteins [86].
The City of Cleveland conducted a research study to determine the cause of the
aftergrowth that occurred during the hypochlon nation of the streams [86].
Also, possible methods to reduce aftergrowth were investigated. The study
consisted of: (Da stream study of bacterial aftergrowth resulting from
hypochlorination, and (2) bench scale studies on possible relationships
between aftergrowth and chlorination due to chlorination-induced changes.
Conclusions of the bacterial aftergrowth study are summarized as follows:
* Hypochl on nation of streams results in a significant reduction of
indicator bacteria; however, as soon as the chlorine residual
dissipates, a bacterial aftergrowth occurs.
• Fecal streptococcus exhibited a very limited ability for aftergrowth
in the laboratory. Fecal coliforms displayed a moderate ability for
aftergrowth. Total coliforms were capable of aftergrowth that
closely approximated, or exceeded, their respective initial levels.
» Factors found to significantly affect bacterial aftergrowth are:
(1) the extent of dilution of the chlorinated water; (2) time
available for aftergrowth between chlorination and dilution; and
(3) levels of residual chlorine.
• While maintaining a 6 mg/L chlorine residual throughout a laboratory
study, no significant decrease in aftergrowth was noted by
increasing the chlorination detention time from 15 minutes to 72
hours.
* Proteins, as analyzed by the Lowry Method for protein deterrmnation,
were greatly increased in stream water samples upon the addition of
sodium hypochlorite. It is assumed that chlorine cleaves larger
protein molecules into smaller proteins, peptides, and ami no acids
which yield more reactive sites to react with the Lowry color
development reagent. All the reactive nitrogenous organic compounds
were calculated as protein. Since both laboratory and field studies
show bacterial populations were greater after chlorination than
before, it is further hypothesized that the smaller nitrogenous
compounds were more easily utilized by the bacteria for growth and
reproduction which could be significant in the rate and magnitude of
bacterial aftergrowth.
* Other than of proteinaceous material, there were no appreciable
chlorination induced chemical-physical changes in the water samples
studied that could be demonstratably related to bacterial
aftergrowth.
A multipurpose investigation of surface water quality and disinfection was
conducted in a 8100 ha (20 000 acre) test site at The Woodlands, Texas [84].
It was found that following disinfection of storrnwater with either chlorine.
249
-------
ozone, or bromine with dosing up to 32 mg/L, aftergrowth occurred after 4 to 8
days. Aftergrowth occurred only In the total coliform group.
Biological Indicator Organisms
Total coliforms, fecal coliforms, and fecal streptococci are the most common
biological indicator organisms used to measure water, wastewater, and
stormwater pathogenic quality and disinfection efficiency. Because extremely
high coliform counts can come from natural background sources other than
humans, the use of the coliform group as an indicator of the presence of
pathogens in stormwater has been questioned [84, 85], Analysis of soil
samples taken from areas adjacent to established stream sampling stations and
from other areas of The Woodlands, Texas, yielded positive values for all
indicator bacteria groups, including pathogens [84]. In Baltimore,
investigations have also revealed little or no correlations between indicator
and pathogenic bacteria in storm and stream samples; however, pathogens were
received in all stormwater samples [85].
In using coliform counts to measure or control disinfection efficiency, and as
a basis of design when the possibility of aftergrowth of coliform organisms
exists and/or potentially high background levels exist, gross over or under
design of disinfection facilities may result.
Studies have been conducted to evaluate alternative microbial indicators
including high chlorine resistant organisms, pathogens themselves, fecal
coliforms to fecal streptoccus ratios, and adenosine triphosphate [83, 84,
89, 92].
The coliform group of indicator organisms have a relatively low chlorine
resistance when compared to such pathogens as enteric viruses and protozoan
cysts. Three indicators were investigated which were resistant to
chlorination in the range considered necessary for the inactfvation of
pathogens and viruses. These included a yeast and two acid-fast bacillus
[83]. Similar studies were conducted in Syracuse, New York, using
bacteriophage f2 and 0X174, Polio-1, and other viruses that are more resistant
to chlorination than the coliform indicator bacteria [89].
Measurement of pathogens themselves is a method to identify microbial quality
directly [85, 92]. However, procedures to isolate and enumerate viruses such as
Salmonella, Shi gel!a, Pseudomonas aeruginosa, and Staphlococcus aureus are
considerably more difficult than for the coliform group. Better methods and
reliable qualitative recovery procedures for the enumeration of pathogenic
microorganisms should be developed to identify pathogen presence and impact in
storm runoff and combined sewer overflows [85],
Measurements of fecal streptococcus in addition to total and fecal coliforms
may provide an indication of the source of the polluting bacteria groups
through the use of the fecal coliforms/fecal streptococci ratio (FC/FS) and
fecal coli form/ total colifomi ratio (FC/FT) [82, 84, 85]. An FC/FT ratio of
greater than 0.1 is believed to be indicative of sewage; however, a firm FC/FT
ratio has been difficult to establish. An FC/FS ratio of 4.0 or greater is
believed to be indicative of human sources and a ratio of 1.0 or less is
believed to be indicative of animal sources. The FC/FS ratios between 0.7 and
250
-------
4.0 are difficult to interpret. It is suggested that FC/FS ratios be applied
carefully and that the ratios are most meaningful when data are collected at
discharge points to the receiving water. Upon entering receiving waters, the
levels of each of the microorganisms may be affected by numerous environmental
factors and differential microbial die-away [85].
In samples of storm runoff, FC/FS ratios of less than 1.0 have been noticed
and FC/FS ratios representative of combined sewer flows had only 18% of
samples greater than 4.0, indicating animal sources of contamination [85],
A potential alternative to microbial indicators is the use of adenosine
triphosphate (ATP), a substance that is universally found in all living cells.
Significant decreases in ATP that parallel bacteria reductions have been
observed during the disinfection process. It may be feasible to use ATP as an
instantaneous measure and a control for disinfection processes [89].
Costs of J>tormwater Disinfection Systems
Costs of disinfection systems used to treat combined sewer overflows and
stormwater discharges can vary greatly depending on the complexity of the
system. Stormwater disinfection must be flexible and capable of automatic
operation to handle intermittent and varying flows and volumes. Summaries of
typical disinfection costs are presented in the literature for chlorine gas,
hypochlorite, and ozone systems [2, 27].
Costs used for disinfection alternative selection should be evaluated using
local conditions and requirements. These can include disinfection and
receiving water requirements amd standards, equipment and disinfectant
availability and costs, and system control and operation requirements.
Improvements and changes in on-site generation equipment may make these
alternatives more economically attractice for storm flow applications. Ozone
generation, although more expensive than other methods of disinfection, may
become an economically feasible alternative in light of increasingly strict
control of residuals and compounds formed by chlorine disinfection and the
increasing costs of chlorine [82].
Cost curves comparing chlorine gas, chlorine dioxide, and hypochlorite
generation disinfection systems have been developed and are presented in
Figure 59. These costs (ENR 2000) include manufactured equipment, piping,
housing, electrical and instrumentation, and miscellaneous items. No
allowance for contingency or land was included. Operation and maintenance
cost curves have also been developed and include annual labor requirements;
miscellaneous supply costs for chlorine gas, chlorine dioxide, and
hypochlorite disinfection systems; and power requirements for hypochlorite
generation [27],
ILLUSTRATIVE PROBLEMS
Comparison of several stormwater treatment technologies together with examples
of process design and cost evaluations are presented in Example Problems 7-1
through 7-5. The problems include a cost-effectiveness comparison of total
251
-------
storage and storage/sedimentation; design of a swirl concentrator, including
geometry modifications; development of an equation for estimating operation
and maintenance costs for storage facilities; and a method for optimizing
integrated storage/treatment facilities. An evaluation of land requirements
and design considerations for land treatment of stormwater is also presented.
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it
0
*
F
>
jT
/
>
X
f
OJx
+
-J^
*"
^
^*
J^
CHLORINE QAS
FEED COSTS
/
s
s
/
'
/
/
X
t
*
f
/
f
* '
2 3458788 2 34887*8
mo r 80Q ? a ooo
DESI8N FEED RATE, I b/d
Ib/d K 0.454= k|/d
Figure 59. Chlorine disinfection cost curves, ENR 2000 [27],
252
-------
EXAMPLE PROBLEM 7-1: ASSESSMENT OF STORAGE AND STORAGE/SEDIMENTATION COSTS AND COST EFFECTIVENESS
Given a frequency curve of storm rainfall, determine the costs, annual pollution reduction, and cost
effectiveness for a storage and a storage/sedimentation facility. The storage facility is to be design
to capture 95» of the total annual runotf volume. The storage/sedimentation facility is to oe designed
to capture 50« of the total annual runoff volume and treat those flows exceeding storage capacity by
sedimentation.
5 peci f jed Condi ti cms
1. Drainage area = 1000 acres.
Average runoff coefficient = O.bO
Total annual rainfall = 44 in.
Average suspended solids (SS) concentration In runoff = 400 mg/L
$Q.25/gal of volume, for concrete
2.
3.
4.
B.
Construction costs (ENR 2000) for earthen-lined reservoirs
sedimentation tanks, $1.QQ/gal of volume.
Assumptions
1. The storage volumes are Based on a frequency plot of total storm rainfall, as shown in Figure 7-1.
100
10 19 30 2 i
TOTAL SID SB JUJXFALL In
3 .0
Figure 7-1. Percent chance of obtaining less than total
storm rainfall amount.
2. It is assumed that runoff follows the same relationship ot frequency as the rainfall curve.
3. Average flowrate to tne storage/sedimentation facilities for flows exceeding storage capacity is
oased on the average of tne maximum hourly rainfalls for each storm.
4. All flows totally contained in storage are to be released back to the interceptor and receive 851
removal at a dry-weather treatment facility.
SoUiti on
1. Compute the volume and the construction cost for 95% storage of the annual runott volume. From
Figure 7-1, capture of storm rainfalls of less than 1.6 in. will result in a 95% capture of the
annual rainfall volume.
a. Determine design runoff amount using a iOT runoff coefficient.
Design runoff amount = 1.6 in. x 0.50
= ti.SQ in.
253
-------
b* Determine storage volume required.
Storage volume - (0-80 1n. x 1 OMacres}f (43 560 ft2/acre)
= 2.90 x 106 ft3
or 21.7 Mgal
c. Compute the construction cost of the storage facility.
post = 21.7 x 106 gal x $0.25/gal
- $5 425 000
d. Adjust ENR 2000 costs to current costs.
ENR 2500 costs = $5 425 000 x 1.25
= $6 780 000
2. Dttemlne the volume and the construction costs for 50% storage of the annual runoff volume tor the
storage/seaimentatlon facilities:
Storage volume - ([0'24 * °-5f\ * 1000) (43 560)
= 435 600 ft3
or 3.26 Mgal
t>. Cost of storage facility = 3.26 x 1Q6 gal x $1.00/gal
" $3 260 000
c. ENR 2500 cost =• $3 260 000 x 1.25
«• $4 075 000
3. Determine the total SS removed by the storage system capturing Bb% of the annual runoff volume.
a. Compute annual runoff volume for a total annual rainfall of 44 1n.
Annual runoff volume = ([44 x 0.50J x^OOOl (43 560)
= 79.8 x 106 ft3/yr
or 597 Mgal/yr
b. Compute annual SS load at 400 mg/L « 400 ppn
Annual load = 597 Mgal/yr x 8.34 Ib/gal x 400 ppm
= 2 x 10° Ib/yr
c. Compute the SS load contained in storage
SS captured = 2 x 106 Tb/yr x 0.95
1 " 1.9 x 106 Ib/yr
d. Compute the SS removed by conventional treatment at a rate of 852.
SS removal = 1.9 n 106,x 0.85
= 1.62 x 10 Ib/yr
4. Determine the total SS removed by storage/sedimentation capturing B0% of the annual runoff
volume and treating the remainder by sedimentation.
a. Compute the annual SS load contained in storage and treated at a conventional dry-weather
facility achieving 85S removal.
SS removal - 2 x 106 Ib/yr x 0.50 x 0.85
= 850 000 Ib/yr
b. Determine the average flowrate for flows that exceed storage capacity using an average
maximum hourly rainfall of 0.20 1n./h.
Runoff rate = ^0--in'/h *. O..S_Q)..(.1QOO acres) (43 560 ft^/acre) (7.48 gal/ft3) (24 h/d)
ttm til*/ It
= 65.2 Mgal/d
254
-------
c. Determine surface area of the storage/sedimentation basin at a TO ft sidewater depth (swd).
- 435 600 ftj
Area 10 ft ,
= 43 560 fr
d. Compute average hydraulic loading rate.
Hydraulic loading rate
1500 gal/ft2.d
e. Determine the average SS removed by sedi men cation at a hydraulic loading rate of 1500
gal/ftz-d. Using Figure 38, SS removal = 30%.
SS removed by sedimentation •= 2 x 106 Ib/yr x 0.50 x 0.30
= 300 000 Ib/yr
f. The total SS ranoved by the storage/ sedimentation facilities 1s 850 000 + 30u QUO =
1.15 x 106 Ib/yr.
5. Estimate the annual costs, Including various land costs for storage and storage/sedimentation.
Also determine the cost effectiveness for each type of storage.
a. Determine the gross land area requirements for storage, using a 10 ft swd and the typical
section of an earthen embankment as shown In Figure 7-2.
4! It
Figure 7-2. lypical earthen embankment detail.
Effective water surface area - -'9 y^1^- f- (see 1 .b.)
= 2§0 000 ft2
or 538.5 ft x 538.5 ft
Gross area * (S38.5 + [2 x 41 ])2
= 385 000 ft2
or 8.84 acres
b. The area required for storage/sedimentation = 43 550 ft^/acre = '"°
No additional area is required because of the vertical concrete walls
c. Estimate the land cost for storage at $10 000/acre.
Land cost = 8.84 acres x $10 000/acre
= $88 400
d. Compute the total construction and land cost for storage.
Cost = $6,780 000 + $88 400
= $6 868 400
255
-------
e. Compute the amortized construction costs for storage using a 20 yr life at 7% Interest.
Amortized construction cost = total cost x capital recovery factor (20,7)
- $6 868 400 x 0.09439
= 648 000
f. The amortized construction costs for both storage and storage/sedimentation using land costs
of $10 000/acre, $25 000/acre, and $50 000/acre are summarized as follows:
Amortized construction costs. $/yr
Land costs, $/acre
10 000 25 000 50 000
Storage 648 000 661 000 682 000
Storage/sedimentation 386 000 387 000 339 000
Determine the cost effectiveness using amortized construction costs together with the total
pounds of SS removed per year for the two types of storaqe at each land cost. The cost
effectiveness for storage at $10 000/acre = —J648 000/.yr_
1.62 x 106 ib/yr
= $0.40/lb
Cost effectiveness values for all determinations are summarized as follows;
Cost/lb SS removed, $/1_b
Land costs, $/acre
1QOO 25 OOP 50 OOP
Storage 0.40 0.41 0.42
Storage/sedimentation 0.34 0.34 0.34
Comment
Although actual construction and land costs will vary from the values in this example, it can be
seen that land costs affect storage costs and cost effectiveness to a greater degree than storage/
sedimentation. A higher percentage of large total rainfall would require even larger storage
facilities; however, If the majority of tota.1 rainfall volumes were small, total storage may
approach the most economical and cost-effective solution.
EXAMPLE PROBLEM 7-2: DESIGN OF A SWIRL CONCENTRATOR/REGULATOR
Using the design curves developed from model studies [29], determine the design details for a swirl
concentrator/flow regulator removing 90S settleable solids, and indicate the range of removals over
the range of influent flows. Also, develop revised design dimensions using a weir height IHJ equal
to the Inlet dimensions (D-|).
Specified Conditions
1. The design flow = 40 ft3/s
2. The influent sewer size = 3 ft
Assumptions
1. The peak flow = 90 ft3/s
256
-------
Solution
1. Determine the standard design details (H^/D2 = 0.25) for the swirl concentrator/regulator.
a. From Figure 7-3 (Figure 7 in reference [29]), determine the chamber diameter (D2) for a
design flow of 40 ft3/s with a chamber inlet dimension of 3 ft ID-]).
10 IS 20 29 30 394015
OISCH*RGE,n3/5
Figure 7-3. Swirl chamber diameters for
90S settleable solids recovery [29].
24 f t
b From Figure 7-4 (Figure 15 1n reference [29]), check the settleable solids removal
efficiency for a 24 ft diameter chamber,
10 20 30 40 SO 100 SOB
Figure 7-4. Settleable sol Ids recovery for
D! = 3 ft at H/D = 0.25 [29],
Interpolating the recovery curve for Da = 24 ft, the swirl efficiency - 87%
257
-------
f.
Adjust the swirl chamber diameter to achieve 90S removal. From Figure 7-4, the D£ dimension
is interpolated from the curves at SOS.
Adjusted D£ = 25 ft
Compute height of the swirl chamber (HI) from relationship Hi/Dg = 0.25.
HI = 0.25 x 25 ft
H] = 6.25 ft
e. Determine the standard design details as shown in Figure 47, using the D..,
derivAH ahnuo* *
derived above:
and H, values
D
.; = 0.56 x D2
h] =0.50 x DI
h2 = 0.33 x 0]
bl = 02 T 18
R! =0.39 x 02
R2 = 0.25 x
13 " 0.67 x D2 = 16.7 ft
l!
1.
1.
9.7 ft
6.2 ft
2.6 ft
.9 ft
.5 ft
.0 ft
.4 ft
D2 =
R3 = 0.104 x D2 =
84 « 0.188 x D2 =
R5 = 0.61 x
4.7 ft
= 15.3 ft
Estimate the settleable solids removal over a range of expected flow of 10 to 90 ftfys using
Figure 7-4
10 ft3/s - removal = 100%
40 ft3/s - removal = 901
50 ft3/s - removal = 751
60 ft3/s - removal = 47X
70 ft3/s - removal = 28%
90 ft3/s - removal = 121
2, Determine the revised swirl chamber dimensions using a weir height (Hi) equal to the inlet
diameter (Di) of the standard design. The revised swirl concentrator mil have the same
settleable solids removal efficiency as the standard design. The geometry modification is made
utilizing Figure 7-5 (Figure 10 in reference [29]).
MODEL
VALUES OUTSIDE »RE•
Em* POUTED
a o -
. 2.0 -
I 0
STANDARD DES1QK
LiME FOB
H,/Bj»O.SS
V*-6!a(ETRI
\ KODIFICATIOIT
tCIIRKJ
9 ID 11 12 13 14 15 II 11
V»t
Figure 7-5. Swirl geometry
mooTflcatidn curves [293.
a. Compute D2/Di using the standard design values.
= 25/3
« 8.33
258
-------
b. Enter Figure 7-5 at O^/ft] = 8.33 and move vertically to the standard design line. A revised
DZ/DT value is obtained by moving along or parallel to the geometry modification curve to the
specified Hi/D^ value, In this case, H|/D] = 1.0; and then down to the revised Dg/Dj value of
approximately = 10.0.
c. Compute the revised chamber diameter (Og).
D? = 10.0 x DI
= 30 ft
d. The other design dimensions are then recalculated using the new D], Dg, and H-j values.
Comment
In detailing a swirl concentrator/regulator, the designer should choose a swirl inlet dimension
approximately the same size as the influent sewer. However, where there 1s a choice of inlet
sizes, the largest inlet size will result in the smallest, most economical structure. It is
recommended that swirl designs also Include an emergency overflow for flows that exceed peak design
capacity. The swirl design curves developed from the model studies are limited by the fact that
inlet dimensions of only 1 ft increments are provided for inlets 2 ft and larger-, therefore, estimates
of swirl size will have to be estimated or interpolated for odd sizes of inlets. The swirl design
is also limited by the model study design limits for D^/D-, of 6 to 12.
EXAMPLE PROBLEM 7-3: ESTIMATION OF OPERATION AND MAINTENANCE COSTS FOR STORASE FACILITIES
Develop a normalized operation and maintenance cost relationship such that average annual operation
and maintenance costs may be estimated as a function of storage volume.
Spec If ied Cond 1 ti gns
1. Storage volume, capital, and operation and maintenance costs for storage facilities are
taken from Table 73.
2. Cost basis: ENR 2000.
Assumptions
1. Annual operation and maintenance costs are adjusted by the total storage capacity and the
capital costs to obtain an equal basis of comparison, using the data for several sizes and
types of storage facilities.
2. The resulting curves and equations represent an average normalization for any type and size
of storage facility and are assumed to include labor, miscellaneous supply costs, and
energy costs.
Solution
1. Deternne the operation and maintenance cost factor (Cf) for the storage facilities
presented in Table 73,
a. For Akron, Ohio, the Cf is evaluated by dividing the annual operation and
maintenance cost by the storage capacity and the capital cost.
Cf = S2 900
(1.1 Mgal x $455 700)"
= 50.0058/Hgal-S capital cost
259
-------
b.
Operation and maintenance cost factors for the storage facilities are summarized
as follows:
Annual operation and
maintenance cost, $
2 900
51 100
80 000
§7 600
100 200
2 700
6 ZOO
3 340
14 400
Storage
volume, Hgal
1.1
3.9
1.3
1.2
12.4
2.8
0.36
0.20
0.25
Capital cost, $
455 700
1 774 000
6 495 000
9 488 000
11 936 000
744 000
520 000
883 000
320 000
Lf
$/Mgal-$
0.0058
0.0074
0.0095
0.0086
0.0007
0.0013
0.0331
0.0189
0.1800
c.
The cost factors are plotted against storage volume, as shown in Figure 7-6, along with
the best fit curve representing the average normalized conditions.
0 OJ5 _
o 020 .
o 019
o 010
•» 0 005 .
3 10
STORAGE YOLU1E H(Il
15
Figure 7-6. Operation and maintenance cost function for storage facilities.
d. The best fit curve has the equation:
Cf = 0.0105 V1 -W6 (7-1)
where Cf = cost factor, $/Mgal-capital cost
V • storage volume, Hgal
the correlation coefficient » 0.86
2. Develop a normalized operation and maintenance cost equation for storage facilities using the
best fit curve equation from Figure 7-6.
Annual operation and maintenance costs are found by multiplying the cost factor at the
required storage volume by the storage volume and the estimated capital cost;
Operation and maintenance cost = Cf x V x Cc
= (0.0105 V-l-0476) v x Cc
- (0.0105 V-0.0476) Cc
where V = storage volume, Mgal
Cc = capital cost, $
(7-2)
260
-------
Compare the results of the operation and maintenance cost equation with estimates obtained
from the cost curves developed for stormwater facilities [27]. Capital costs for use in
the equation are taken from the storage reservoir capital cost curve for concrete uncovered
storage basins. Figure 34, to make an equal basis for comparing the operation and
maintenance cost curves [27]. The comparison for storage facilities of 2, 5, 10, and
15 Mgal capacity is summarized as follows:
Operation and Operation and
Storage Capital cost, $ maintenance cost, $/yr maintenance cost, $/yra
volume, Hgal (Figure 3.4). (Equation 7-2) {cost curves [27])
2 500 000 5 100 5 880
5 900 000 8 750 7 950
10 1 300 000 12 200 11 300
15 1 700 000 15 700 13 600
a. Includes labor interpolated for 40 events per year at $10/h,
Cottroent
The operation and maintenance costs determined by Equation 7-2 provide a means and flexibility
for estimating costs on a first-cut basis for both large and small storage facilities of
simple or complex design and operation. Operation and maintenance costs based on the complexity
of the design or process are controlled by the capital cost of the facility as well as the
volume of storage. The operation and maintenance values generated by the equation, using the
capital cost values developed in reference [27], compare favorably with those taken from the
curves.
EXAMPLE PROBLEM 7-4: STORAGE/TREATMENT OPT 1 Ml Z AT I OH
Evaluate the cost of total treatment and total storage and determine the optimum storage/
treatment combination for a given design rainfall at a level of treatment costing $30 000/Mgal-d.
Specified Conditions
1. Drainage area = 1000 acres.
2. Average runoff coefficient = 0.50
3. Capital cost for treatment = S30 000/Mgal-d
4. Capital cost for storage c Sl.OO/gal
5. Operation and maintenance costs for storage taken from Equation 7-2.
6. Operation and maintenance costs for treatment = 0 015 +• 0.027 (treatment cost). Developed
for reference [93].
Assumptions
1. Assume storage is to be dewatered in 24 hours.
2. The design rainfall rate » 1.2 In./h
3. The peak rainfall is assumed to be 1.5 x design rainfall.
4. The duration of rainfall equals runoff duration.
Solution
1. Determine the treatment capacity and tost to treat the total runoff. The treatment
rate will be designed for the peak flow, without storage or flow attenuation.
a. Peak rainfall = 1.5 x design rainfall
= 1.5 x 1.2 in.
= 1.8 1n./h
b. Determine the peak treatment rate (Q).
n = (1.8 in./h xQ.SO x 1000 acres) (43 560 ft2/_acr_e}_(7.48 gal/_ft3) (24 h/d).
(12 fn./ft) (1.0 x 106 gal/Mgal)
= 586 Hgal/d
261
-------
c. Compute the cost of treatment.
Cost = 586 Hgal/d x $30 OQQ/Mgal-d
! = S17.58 million
2, Determine the cost of storage assuming the stored volume is dewaterd in 24 hours
through treatment costing $30 000/Hgal-d. Using Equations 4-la and 4-2a:
a. Storage volume = 0.02715 Kiflt] - (Q * 24}tg : Eq.4-1a
= 0.02715 x 0.50 x 1.2 x 1000 x 1.0 - (Q - 24} x 1.0
= 16.29 - (Q * 24)
= 16.29 - (16.29 * 24)
= 15.61 Hgal
b. Cost of storage/treatment = 0.02715 KlAtjCg + Q [Ci - -f^j: Eq. 4-2a
= 16.29 x 1.0 + 16.29 J0.03 - 1'°2)41'0]
= 16.29 - 0.19
= $16.10 million
c. Evaluate the cost of storage and treatment individually for this situation.
Storage cost = 15.61 Hgal x Sl.O/gal = $15.61 million
Treatment cost = 16.29 Kgal/d x 50.03/gal-d = $0.49 million
3. Determine the optimum storage/treatment combination using annual capital costs and total annual
costs (Including operation and maintenance).
a. Compute the storage volume required to reduce the peak treatment rate to the average
design treatment rate, using the linear relationship shown in Figure 7-7.
2.0
1.5
1.0
_ MINIMUM STORAGE
REQUIRED AT DESIGN
TREATMENT RATE
I
0.5
DURATION, h
1,0
PEAK TREATMENT RATE
WITHOUT STORAGE
DESIQN TREATMENT
RATE
.MINIMUM TREATMENT RATE
REQUIRED TO OEWATER
TOTAL STORAGE IN 24 h
Figure 7-7. Relationship of treatment rate and storage volume
for treatment rates greater than 0.6 in./h of rainfall.
The shaded area represents the storage volume required to provide the average design
treatment rate of 1.2 in./h of rainfall. Area •= 1/2 bh.
=, (0.5[1.8 in./h - 1.2 in./h] x 0.5 h) (0,50) (1000 acres) (43 560 ft2/acre) (7.48 gal/ft3)
02 1
= 2.04 Mgal
262
-------
b. Compute the treatment rate at 1,2 1n./h of rainfall.
Treatment rate - (1'2 1n'/h x °'50 x 100° acres) (43 56° ft2/acre^ (7-48 gal/ft3) (24h/d]
(12 in./ft) (1.0 x 106 gal/Mgal)
= 391 Mgal/d
c. Determine the cost of storage and treatment at the design treatment rate.
Storage cost =2.04 Mgal x Sl.O/gal = $2.04 million
Treatment cost = 391 Mgal/d x $0 03/gal-d = $11.73 million
Total cost = 2.04 + 11.73 = $13.77 million
d. Compute the storage/treatment costs for other treatment rates.
Note: At treatment rates of less than 0.6 in./h of rainfall. Equations 4-la and
4-2a may be used. At treatment rates greater than 0.6 in./h of rainfall,
the storage volume 1s computed from Figure 7-7 by multiplying the area of
the triangle at the desired treatment rate by the appropriate conversion
factors.
Costs of several storage/treatment combinations are as follows:
Rainfall,
in./h
0.05
0.1
0.2
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1 7
1.8
Treatment
rate, Hqal/d
16 29
33
65
130
163
195
228
261
293
326
358
391
424
456
489
521
554
586
Storage
volume, Mgal
15.61
14.92
13.58
10 87
9.50
8.15
6.84
5.66
4.58
3,62
2.77
2.04
1.41
0 91
0 51
0.23
0.06
0
Treatment
cost, S million
0.49
0.99
1.95
3,90
4.89
5.85
6.84
7.83
8.79
9.78
10.74
11.73
12.72
13.68
14.67
15.63
16.62
17.58
Storage
cost, $ million
15 61
14.92
13.58
10.87
9.50
8.15
6.84
5.66
4.58
3.62
2.77
2.04
1.41
0.91
0.51
0.23
0.06
0
Total cost,
S million
16.10
15.91
15.53
14.77
14.39
14.00
13.68
13.49
13.37
13.40
13.51
13.77
14 13
14.59
15.18
15.86
16.68
17,58
e.
f.
The total capital costs are coverted to amortized capital costs assuming a 20 year Hfe
at 7% Interest. Compute the annual capital cost at a treatment rate of 16.29 Mgal/d.
Annual cost
$16.10 million x 0.09349
$1.520 million/yr
Compute the annual operation and maintenance costs for each storage/treatment
combination. The storage and treatment operation and maintenance costs at a treatment
rate of 16.29 Mgal/d is computed below:
Storage operation and maintenance
0.0105 x 1S.61"0'0476 x 15.61
$0,144 imlHon/yr
(7-2)
Treatment operation and maintenance =• 0.015 + (0.027 x 0.49)
= $0.028 million/yr
Determine the total annual cost for each storage/treatment combination.
annual cost for a treatment rate of 16.29 Mgal/d is determined below;
Total annual cost = 1.S20 + 0.144 + 0.028
= $1.692 million/yr
The total
263
-------
Total annual costs for treatment rates up to 456 Mgal/d are presented in the following
and are plotted in Figure 7-8,
Treatment
rate, Mgal/d
16.29
33
65
130
163
195
228
261
293
326
358
391
424
456
Amortized
capital cost,
$ imlllon/yr
1.5ZO
1.502
1.466
1.394
1.358
1.321
1.292
1.272
1.262
1.265
1.275
1.300
1.334
1.377
Operation
costs,
Storage
0.144
0.138
0.126
0.102
0.090
0.077
0.066
0.055
0.045
0.036
0.028
0.021
0.015
0.010
and maintenance
$ million/yr
Treatment
0.028
0.042
0.068
0.120
0.147
0.173
0.200
0.226
0.252
0.279
0,305
0.332
0.358
0.384
Total
annual cost.
$ niiVTIgn/yr
1,692
1.682
1.660
1,616
1.595
1.571
1.i58
1.553
1.559
1.580
1.608
1.653
1.707
1.771
I 80 _
1 8B
1 70
1 80
'-'O
' •*"
I 3D
I JD
ram ANNUAL COSTS INCIUQIKO
-.OPERATION AND HAINTEHAHCE.
-I
UINIIUI COST
100 JDO 300
TRE*rMENr RJtTE Upl/d
400
300
h.
Figure 7-8. Storage/treatment optimization of
treatment costing $30 000/Hgal-d.
Determine the optimum storage/treatment combination. From Figure 7-8, the optimum
solution, using capital costs only, is approximately $12.6 milHon/yr at a treatment
rate of 295 Mgal/d and a storage volume of approximately 4,5 Hgal, H1th operation
and maintenance taken Into consideration, the optimum combination 1s at a treatment
rate of 250 Mgal/d with storage at 6.0 Mgal, with a total annual cost of $1.55 milllon/yr,
Comnent
Storage is usually required before treatment of storm and combined sewer overflows to attenuate
peak flows and reduce the size of the treatment facility. There is an optimum combination of
storage and treatment that produce the least capital cost solution. When operation and
maintenance cost 1s Included, the least cost combination shifts to a more storage-intensive
solution. Furthermore, as the unit cost of treatment increases, the least cost solution also
favors more storage and less treatment. An evaluation of the optimum combinations of storage/
treatment at unit treatment costs of $35 000, $40 000, and $45 000/Hgal-d using both amortized
capital costs and total annual costs shows that as the unit treatment cost increases, the
264
-------
optimum treatment rate moves toward the minimum treatment rate of 16,3 Hga1/d, The addition of
operation and maintenance costs also shifted the optimum rate toward 16.3 Hgal/d as shown below:
Optimum, treatment rate> Hgal/d
Unit treatment Using amortized Using total
cost, l/Hgal-d capital costs annual cost
35 000 260 195
40 000 220 16.3
45 000 16.3 16.3
EXAMPLE PROBLEM 7-5: LAND TREATMENT OF STQRWATER
Determine the land requirements for wetlands, rapid infiltration, and overland flow stornwater land
treatment systems, Show the maximum and minimum land requirements based on annual and weekly
application rates.
Specif led Conditions
1. Drainage area = 1000 acres.
2. Runoff coefficient = 0.50
3. Average annual rainfall = 44 in.
4. Use the design criteria shown 1n Table 118.
Assumptions
1. The design weekly rainfall equals the total storm rainfall of 1.6 in. as shown in Figure 7-1.
2. The effects of storage or flow attenuation are not considered in determining the land requirements
using the weekly rainfall rate.
Solution
1. Determine the annual and the weekly runoff volume from the 1000 acre area.
.. Annual runoff - (44 in./yr) (Q.50) (jOOO^cres) (43 560 fiacre)
= 79.86 x 106 ft3/yr
b. Meekly runoff * t1'6 !">k) <° 50) ™*s) (43 56°
- 2.90 x 106 ft3/wk
2. Determine the maximum and minimum land requirements for wetlands treatment, using design criteria
from Table 118.
a. Maximum land requirement = 79'86 | f£7yjr /
= 19.97 x l(Pft2
or 458 acres
b. Minimum land requirement °
= 1.39 x l()6~ft
or 32 acres
(2.9 x IP6 ft3/wk) (12 in./ft)
25 In./wk
c. Compute the annual application rate at the minimum land requirement condition.
79.86 x 10s ft3/vr
Maximum annual application rate =
(32 acres) (43 560 ftz/acre)
= 57 ft/yr
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3. Determine the maximum and minimum land requirements and the maximum annual application rate for a
rapid Infiltration system.
u . , . * 79.86 x TO6
a. Maximun land requirement = - go -
b. Minimum land requirement
3.99 x TO6 ft2
or 92 acres
(2 9 x 10^) (121
-*— '- - v — '
= 2.5 x 10= ft2
=6.7 acres
-,, ^ * 79.86 x 106
c. Maximum annual application rate ° "($.7) (43
= 273 ft/yr
4. Determine the maximum and minimum land requirements and the maximum annual application
rate for an overland flow system.
79 85 x 10^
a. Maximum land requirement = —'-—^g
= 7.99 x 106 ft2
or 183 acres
b. Minimum land requirement •= -^-9--x- ]° ) ^
=• 2.18 x 106 ft2
or 50 acres
c. Maximum annual application rate ° (50) {43 §gQ\
= 37 ft/yr
Coment
The ranges of application rates presented in Table 118 were developed for municipal waste-
water treatment systems and, therefore, should serve as first-cut guides until more detailed
studies using land treatment processes for controlling stormwater are evaluated [78]. These
ranges reflect a wide variation 1n soil types, permeability, slope, climate, and vegetation
cover. In this t*xanple, the range of annual application rates was narrowed by considering
land area requirements based on a design weekly rainfall rate. The land requirements for
wetlands range from 3 to 4656 of the watershed area. This land, however, would most
probably be existing marsh or unusable land areas receiving stormwater discharges directly,
or at best an existing marsh operated under a controlled mode of application. Land require-
ments for rapid infiltration range from 1 to 9X, and for overland flow from 5 to 18X of the
watershed area. These land treatment alternatives would require usable or developable land
and thus may be limited by land availability and costs.
As with biological treatment systems, overland flow systems were developed for continuous
wastewater application to maintain a viable biological mass supported by the grass structure.
Because of the intermittent nature of rainfall/runoff, this type of system is reduced to a
grass filter for stormwater flows because of the length of time required to develop,
stabilize, and sustain a biological mass. Supplemental water may also be required to maintain
grass growth during long dry periods. Difficulties may anse with other land treatment
methods due to the variability and characteristics of stormwater runoff. Pretreatment may
be required for rapid infiltration systems to prevent clogging of the soil by high suspended
solids loads.
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SECTION 8
SYSTEM APPLICATIONS
As has been indicated in previous sections, there is no one single method that
is a panacea to all combined sewer overflow or storm drain discharge problems.
The size and complexity of urban runoff management programs are such that
there is a need for an integrated approach to their solution. The type of
problems associated with any given community is dependent upon a number of
variables; as a result, the solution for a community must be developed to fit
the needs of that particular urban area. The solution is. most often a combi-
nation of various best management practices and unit process applications.
Important considerations with respect to development and implementation of an
urban runoff management program are the regulatory constraints and public
attitudes on pollution and environmental objectives that must be met. Often
the constraints and attitudes are subject to change with time. This can
result in alteration of the ground rules for engineering assumptions so that
programs lacking flexibility may be, or in some cases, have been grossly
outdated before implementation can be effected. Thus, the political,
economic, and environmental constraints affecting an urban runoff management
program must be monitored continuously so that the programs can be updated or
modified as necessary.
CASE STUDY DESCRIPTIONS
The presentation of each stormwater management system application is organized
into six parts: (1) problem identification, (2) counter-measure philosophy,
(3) design description, (4) cost data, (5) performance and maintenance, and
(6) ongoing projects. A variety of system applications are described ranging
from major urban metropolitan areas to small suburban communities.
Boston,Massachusetts
Combined sewer overflows have contributed to the deterioration of industrial,
commercial, and recreational resources of Boston Harbor and the rivers
tributary to it [1], Primary treatment is provided to the intercepted flows
at two wastewater treatment plants. However, numerous locations still exist
in the Boston Harbor area where, during rainstorms, combined sewage overflows
into the receiving waters untreated. These result in bacterial pollution,
floating solids, slicks, and sludge deposits.
A wet-weather flow master plan, based largely on preliminary Chicago deep
tunnel studies (discussed later in this section), was presented to the City of
Boston in 1967 [2]. Four alternatives were studied: (1) complete separation,
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(2) chlorination detention tanks, (3) surface holding tanks, and (4) deep
tunnels. The deep tunnel alternative was presented because it appeared to
offer the best and only feasible method for the complete elimination of
overflows. However, following continued review and study of the problems, a
demonstration surface detention and chlorination facility was placed into
operation in May 1971 at Cambridge, Massachusetts (the Cottage Farm Combined
Sewer Detention and Chlorination Station) indicating a viable alternative to
the deep tunnel plan.
In 1975, the combined sewer overflow problem was reviewed again in conjunction
with the needs for the Boston Harbor-Eastern Massachusetts Metropolitan Area
[1], The major alternatives were (1) sewer separation, (2) overflow
diversions via Boston's proposed deep tunnel plan, and (3) intermediate
approaches of a decentralized nature. The recommended course of action was to
upgrade the two existing treatment plants to secondary treatment and to begin
facilities planning for projects identified in the decentralized plan for
combined sewer overflow regulation. The decentralized plan would continue
present remedial practices and allow piecemeal implementation with immediate
opportunities for solving high priority problem areas. The present plan
calls for consolidation of the combined sewer outfalls into several groups,
each of which would be connected by conduits to transport overflows to
regulation facilities for treatment and discharge.
Treatment would consist of several detention facilities located throughout the
area where the flow would be stored or, depending on the magnitude of the
storm event, detained prior to discharging the overflow. The flow would be
disinfected by introducing chlorine upstream from the tanks. The tanks would
be designed to provide 15 minutes detention for the peak design flow. The
tanks would include floating scum baffles and screens installed between the
scum baffle and the overflow weir to polish the overflow before discharge.
The stored flow would be returned to the interceptor to receive secondary
treatment at one of the two treatment plants.
According to the Report:
...the largest benefits in pollution reduction in decentralized systems
will probably come from first flush capture and diversion to the dry
weather flow treatment plant and through sedimentation, skimming and
disinfection as a result of detaining overflows, while other treatment
processes will be employed where such prove to be necessary for further
polishing. [1]
The total cost for the various alternatives ranges from $254 to $279 million
{ENR 2000) excluding projects currently underway (separation in portions of
Cambridge and Somerville and construction of the MDC Charles River
Chiorination-Detention-Pumping Station Project).
Chicago^ Illinois
In 1967, the Metropolitan Sanitary District of Greater Chicago initiated its
wastewater facilities planning study with a 10 year cleanup and flood control
program. A major study to develop a comprehensive program for the 972
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(375 mi"2) combined sewer area was completed in 1972. The program, presently
being implemented, is the Tunnel and Reservoir Plan (TARP). The objectives of
the program are:
...to minimize the area's pollutant discharges and the flooding caused by
overflows of mixed sewage and wastewater elimination of the need to
release polluted river and canal flood waters into Lake Michigan. [3]
This final TARP is a combination of several alternative plans designed to
collect urban runoff during all wet-weather conditions except those storms of
a magnitude equal to the three most severe storms recorded to date by the
National Heather Service.
Four tunnel systems comprise the TARP, Each tunnel system consists of three
components: reservoirs, conveyance tunnels, and sewage treatment plants. A
total of three reservoirs, 201 km (125 miles) of conveyance tunnels, and four
treatment plants are included in the plan. The combined storage capacity of
the olan is approximately 167 750 000 m3 (44 310 Mgal) of which 11 350 000 m3
(3 000 Mgal) is tunnel capacity. The total storage capacity is equivalent to
17.3 cm (6.b' in.) of runoff from the combined sewer area, with 1.2 cm
(0.46 in.) of runoff capacity in the tunnels alone. The tunnels, located 46
to 88 m (150 to 290 ft) below ground level, range in size from 5 to 10.7 m
(17 to 35 ft) in diameter. The total planned treatment capacity will be
approximately 96.4 m3/s (2200 Mgal/d) of which 91.2 m3/s (2150 Mgal/d) is
existing. The stormwater treatment rate would be approximately 31.8 m3/s
(725 Mgal/d) or about 0.5 times average dry-weather flow. More than 640
existing overflow points will be eliminated by the TARP systems. The sub-
systems common to all TARP tunnel systems include drop shafts, collecting
structures, and pumping stations. Pumping stations will be constructed
underground at the end of all conveyance tunnel routes and adjacent to all
storage reservoirs. These stations will be sized to allow a full tunnel to
be emptied within 2 to 3 days.
In addition, instream aeration at more than ten locations along the Chicago
River and Calumet Sag Channel are planned to allow the Illinois standards for
dissolved oxygen concentrations to be met.
The Phase I system (tunnels and pumping stations without reservoirs) is under
construction currently. The TARP costs are estimated at $2 553 200 000 (ENR
2000). The breakdown is as follows:
Conveyance tunnels $ 869 800 000
Instream aeration 14 000 000
Treatment plant upgrading 986 900 000
Reservoirs and flood control 682 500 QUO
$2 553 200 000
Additional costs such as sewers, solids disposal, O'Hare Treatment Plant, and
non-TARP flood control will raise the total cost to 12 979 400 000. To date,
approximately $45 000 000 of tunnel construction has been completed and
another $100 000 000 is under construction.
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It is projected that the Phase I tunnel system, with overflows at the existing
outfalls until the reservoirs are completed, will reduce the number of
overflows to the river system to about ten per year. This will result in a
75% reduction in the volume of combined sewage overflowing to the river and a
90% reduction in the combined sewer overflow BODC mass load to the river.
0
D e t roi t, Michigan
Detroit is served by a combined sewer system and a primary treatment plant.
In May 1966, an agreement between the Detroit Metro Water Department (DMWD)
and the Michigan Water Resources Commission required
..the City of Detroit to take immediate steps to decrease the frequency,
magnitude and pollutional content of all combined sewer overflows from
the City's sewer system to the Detroit and Rouge Rivers. [4]
Detroit considered the following alternatives to meet the agreement:
ID systems management utilizing sewer monitoring and remote control of
pumping stations and selected regulator gates to affect in-system storage,
(2) complete sewer separation, (3) retention basins to capture storm
wastewater, and (4) the above in various combinations. After a review of the
alternatives, the systems management approach was selected for implementation
in a demonstration project [4].
The system developed includes telemeter-connected rain gages, sewer level
sensors, overflow detectors, a central computer, a central data logger, and a
central operating console for monitoring and controlling pumping stations and
selected regulating gates. This system has enabled DMWD to apply such
pollution control techniques as storm flow anticipation, first flush
interception, selective retention, and selective overflowing.
The in-system storage potential at locations where remote control facilities
were installed was 526 500 m3 (139.1 Mgal). In addition, there is
approximately 581 200 m3 (150 Mgal} of uncontrolled storage in the system.
Upon receiving advance information on storms from remote rain gages, the
operator initiates a sewer pumpdown procedure to increase the available in-
system storage capacity. This procedure, along with in-system flow routing,
has enabled DMWD to contain and treat many intense spot storms entirely, in
addition to many scattered citywide rains.
Since the completion of the demonstration project in 1971, DMWD has continued
to expand the monitoring project [4]. The change in the system is indicated
in Table 122. The supervisory control system has been expanded with the
addition of four new control panels in addition to the original three. Remote
control facilities including three wastewater pumping stations, four
interceptor regulators, three fabridams, two in-system storage gates, one flow
routing gate, and one suburban connection have been added. In addition, four
suburban retention basins and 11 suburban pumping stations are now displayed.
The DMWD is utilizing sewer system monitoring data to (1) aid in the operation
of the system, (2) predict and verify system response to storm events,
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(3) establish priorities for overflow abatement projects, and (4) develop
computer control algorithms for the various remote control facilities [4],
Additional in-system and offline storage is being investigated.
TABLE 122. COMPONENTS OF THE MONITORING
AMD REMOTE CONTROL SYSTEM [4]
Item
1971 1975
Rain gages
Level sensors
Status sensors
Pumping stations/ pumps
Radar rernoting
Regulators
14
118
68
7/39
0
4
25
214
110
10/52
1
10
Cost data for the additions to the monitoring and remote control system were
not reported.
Milwaukee, Wisconsin
The older areas of the City of Milwaukee are served almost exclusively by
combined sewers, approximately 6240 hectares (15 400 acres). Along the
Milwaukee River within the City of Milwaukee are 62 combined sewer outfalls.
Most of these outfalls, 52, are concentrated in the last three miles of the
river before it discharges into Lake Michigan. A flushing tunnel which
carries dilution water from Lake Michigan discharges at the head of the reach
where the overflows are concentrated. This tunnel has been used since 1888 to
dilute the river water to reduce odors.
A demonstration project completed in 1974 studied the concept of detention
tanks for attenuating combined sewer overflows. Two of the objectives were
[53:
1
2.
Characterize the performance of a combined sewer overflow detention
tank in reducing the pollutional load to the Milwaukee River caused
by rainfall in the test area.
Project the impact of combined sewer overflow detention tanks on the
quality of water in the Milwaukee River.
A 14 760 m (3.9 Mgal) detention
Detention Tank) serving a 230 ha
During the 12 month test period,
tank (Humboldt Avenue Combined Sewer Overflow
(570 acre) area was constructed and tested.
the tank reduced the volume, BOD,-, and
suspended solids loads from this combined sewer overflow location by 65 to
70%. Studies evaluating detention tank removal efficiencies of BODc and
suspended solids indicated that removal due to volumetric retention is much
more significant than removals due to sedimentation [5], Removals due to
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sedimentation generally increased total removal efficiency by approximately 5%
over removals due to volumetric retention alone.
For purposes of demonstrating the cost impact of the problem, an approximate
cost estimate was developed for construction of 13 detention tanks to receive
flows from all combined sewer overflow points on the Milwaukee River in the
city. These tanks would serve an area of 2350 ha (5800 acre). All tanks
would be similar to the Humboldt Avenue facility as far as design criteria are
concerned. The implementation of such a series of tanks would be expected to
reduce the discharge of pollutants from combined sewer overflows by approxi-
mately 8Q% on an annual basis. The total cost for the facilities would be
approximately $45 050 000. This includes $28 300 000 for the tanks, $8 150 000
for pumping stations, and $8 600 000 for sewers. These costs do not include
land, right-of-way, contingencies, or additional treatment facilities.
At the present time, the city is proceeding with the development of a combined
sewer overflow abatement program incorporating both detention facilities and
other treatment methods.
Mount Clemens, Michigan
Combined sewer overflows from the City of Mount Clemens polluting the Clinton
River led to a "stipulation" from the Michigan Water Resources Commission in
1967. With regard to combined sewer overflows, the stipulation called for the
construction of facilities by June 1972. A demonstration treatment facility
was designed to provide treatment to the overflows by means of a series of
aerated lakelets with intermediate microscreening, disinfection, and high-rate
pressure filtration prior to discharge into the Clinton River [6], The
testing and evaluation of this facility was completed in 1973. One of the
conclusions reached regarding the demonstration project was:
The Mount Clemens treatment concept evaluation indicates that it is a
feasible and reliable concept....sampling data has demonstrated that the
capability of the treatment concept to acceptably renovate combined sewer
overflows for fishing and boating and for lawn sprinkling. All water
quality parameters, except the toxic and deleterious substances parameter
(not studied), were met. [6]
Annual suspended solids and BQD§ removal efficiencies of about 951 were
reported for the demonstration collection and treatment facility.
As a result of the demonstration project findings, the city has developed a
citywide project for the abatement of combined sewer overflows. It was
recommended that for a 610 ha (1500 acre) portion of the city a combined
sewage interceptor be installed to collect the overflows and convey them to a
retention basin, the contents of which would be withdrawn at a slow uniform
rate for further treatment. For the remaining 240 ha (600 acre) area sewer
separation by constructing new collecting sanitary and/or storm sewers was
recommended. Construction of the citywide project began in 1974.
The collection and treatment project involves the interception of overflows
(5 year storm) from combined sewers and conveying them to the main pumping
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station at "the retention basin site. The flow will then pass through
sedimentation-resuspension chambers before discharge to an aerated retention
basin. Any excess will overflow into a chlorination basin before discharge to
the Clinton River. Wastewater will be withdrawn from the retention basin at a
constant 0.18 m3/s (4 Mgal/d) rate and conveyed to the existing demonstration
project site for treatment. (Dry-weather flow is now treated elsewhere as
part of the MACOMB County-Detroit Metro Water Department Regional System.)
Treatment will include clarification and disinfection; future chemical
additions for phosphate removal will occur at this location. The water will
then be discharged to three lakelets in series. The initial lakelet will be
an aerated "flow-through" treatment unit. Effluent from the final lakelet
will be filtered through high-rate pressure sand filters before discharge to
the Clinton River. The city has designated the treatment-park site for
development as a recreational facility. The final lakelet is expected to be
acceptable for recreational use and potential use for watering park
landscaping.
The total construction cost for the sewer separation and the collection and
treatment facilities was estimated at $15 HO 000. The sewer separation
portion was $2 160 000. The total project costs (including engineering,
legal, fiscal, administrative, and property and easement acquisition) were
estimated to be 1251 of the construction cost. The treatment facilities are
expected to be on-line early in 1977.
Rochester, jlew York
Within the Rochester Pure Waters District, combined sewer overflows represent
a major pollutional load to the Senesee River, the Rochester Embayment of Lake
Ontario, and Irondequoit Bay, A study completed in late 1976 developed a
master plan outlining the actions necessary to achieve a cost-effective
solution to the receiving water quality impairment caused by combined sewer
overflows [7, 8, 9],
The study was divided into three parts:
t Monitoring and characterization of combined sewer overflows and the
collection of field data necessary to characterize the drainage
areas serviced by the sewerage system
* Pilot plant study to evaluate the applicability of alternatives
t Application of mathematical models to evaluate the effect of
combined sewer overflows on the receiving waters to evaluate the
effectiveness of various abatement alternatives [8]
Three classifications of processes were piloted: (1) solids removal;
(2) chemical precipitation to achieve a greater degree of fine solids removal
along with phosphorus reduction below the 1 mg/L level; and (3) final
polishing and high-rate disinfection to achieve a secondary quality effluent
with respect to BODs and bacterial contamination. The processes investigated
were flocculation/sedimentation with and without chemical addition,
microscreening, grit swirl and primary swirl concentrators connected in
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series, dual media filtration, carbon adsorption columns, and high-rate
disinfection with chlorine and/or chlorine dioxide.
The alternatives investigated included nonstructural alternatives (source
control measures and improved sewer system maintenance practices); minimal
structural alternatives (improvement of existing dry- or wet-weather storage
and treatment facilities); and structural intensive abatement alternatives
(new storage and treatment facilities). Mathematical models were applied to
evaluate these alternatives. The runoff Dlock of the Storm Water Management
Model (SWMM) was used to evaluate the effects of the nonstructural
alternatives. Minimal structural alternatives were evaluated using the SWMM
transport block. To determine the average annual effect of various abatement
measures, the Simplified Stormwater Model was used [8].
The recommended master plan calls for the implementation of interceptor
improvements, regulator modifications, blockage of high impacting overflows,
addition of control structures, implementation of source control regulations,
implementation of an overall control system, construction of wet-weather
treatment facilities at the existing Van Lare Treatment Facility (dry-weather
flows) site, and inline tunnel storage and conveyance. The cost-effective
optimum structural intensive solution based on the 2 year design storm
involves a 12.05 m3/s (275 Mgal/d) wet-weather treatment capacity and a
storage capacity of 227 100 m3 (60 Mgal). The recommended wet-weather
treatment facilities are chemically assisted flocculation/sedimentation
(1 mg/L polymer and 40 mg/L alum) followed by high-rate disinfection. The
estimated co.sts associated with implementation of this master plan are
$7 140 000 - 25%+for the nonstructural and minimal structural alternatives
and $88 570 000 - 20% for the structural intensive storage and treatment
alternative [7]. These costs do not include drainage relief facilities that
are part of the costs reported in Section 2.
The effectiveness of the proposed master plan was reported as follows:
...incorporating the nonstructural and minimal structural recommendations
is projected to reduce the BODg and TKN (total Kjeldahl nitrogen) annual
wet-weather loading to the Senesee River from approximately 363 600 kg/yr
(800 000 Ibs/yr) and 9 090 kg/yr (20 000 Ibs/yr) to 1360 kg/yr (3000
Ibs/yr) and 114 kg/yr (250 Ibs/yr). This will reduce the average annual
potential of dissolved oxygen contraventions of the Senesee River from
approximately 10 days/yr to 1 day/yr.
...The annual CSO (combined sewer overflow) loading of suspended solids
to the Genesee River as a result of implementing the Master Plan will be
reduced from approximately 1 363 6QO kg (3 000 000 pounds) to a value of
less than 4545 kg (10 000 pounds). [7]
Ro_hnert Park t Cal i f o r n i a
The City of Rohnert Park has separate sanitary and storm sewers. However,
high wet-weather wastewater flows are encountered in the sanitary sewers
during the rainy season (October through April). Approximately 95% of the
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average annual rainfall occurs during this period. Peak wet-weather flows
exceed average dry-weather flows by as much as eight to ten times [10].
A demonstration project, completed in 1973, was undertaken to determine the
effect of a surge facility to provide equalized flows to the dry-weather
treatment plant. A unique methoa for maintaining the flow of solids through
the basin was tested. One of the objectives of the study was to compare the
primary sedimentation tank efficiencies for variable versus uniform flow
conditions [10].
The ability of the equalization basin to produce the design uniform flowrate
was documented. The basin operated less efficiently than a conventional
clarifier for suspended solids and BQDs removal due primarily to the
variability in the detention time. The 8005 removals were quite erratic.
Following completion of the demonstration project Rohnert Park joined in the
Laguna Regional Wastewater Treatment Facility. Rohnert Park (including the
Town of Cotati and Sonoma State College) is limited to an average dry-weather
flow of 0.10 m3/s (2,3 Mgal/d) and a peak dry-weather flow of 0.18 rrp/s
(4.1 Mgal/d} to the regional plant. Peak wet-weather flow at the old,
existing plant site is 0.53 np/s (12.0 Mgal/d}.
The abandoned Rohnert Park treatment plant has been converted to a surge
facility for wet-weather flows. The surge facility has a surge basin (old
primary sedimentation basin), a storage basin with two days' detention at
maximum daily flow, a control building, and a chlonnation facility for
emergency wet-weather overflow. Most of the components were retained from the
abandoned plant. The storage basin is composed of three unlined earthen
basins approximately 1.5 m (5 ft) deep with a combined area of 6.9 ha
(17 acres). Total storage capacity is 83 300 m3 (22 Mgal). Flows in excess
of 0.18 m-Ys (4.1 Mgal/d) (are diverted to the surge facility for storage.
When the flow in the interceptor to the regional plant falls below 0.18 ra^/s
(4.1 Mgal/d), flow is released from the surge facility. Construction of the
surge facility was completed in 1976.
Construction cost for the surge facility was $943 000. This was composed of
$390 000 for pumping station rehabilitation, $273 000 for the diversion
structure and chlorination facility, and $280 000 for storage basin earthwork
(including regrading and sludge removal from existing oxidation ponds).
Sagi'naw, Michigan
The problem at Saginaw was typical of most such systems, namely periodic
overflows from the combined sewer system. The distribution of the total
intercepted flow among the 34 regulators was inequitable with some
contributing a disproportionately large percentage. When flows reached 2.5
times the dry-weather flow, the treatment plant capacity, a valve on the
interceptor was closed manually and the flow from one half of the interceptor
system was pumped untreated to the river. The valve was reopened manually
after the storm when personnel were available. This contributed unnecessarily
to the amount of wastes discharged through overflows [113. In 1969, it was
recommended that existing intercepting and stormwater pumping facilities be
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utilized to their optimum in conjunction with five new stormwater holding
facilities. The holding facilities were to have a storage capacity of
85 100 m3 (22.4 Mgal).
In 1972, following application of the Storm Water Management Model (SWMM) to
simulate the operation of the sewer system and proposed storage facilities,
the plan was revised [12]. The revised plan called for construction of seven
storage facilities with a total capacity of 68 800 m^ (18.2 Mgal). In
addition, revisions to existing regulators would add 70 400 m* (18.6 Mgal) of
in-system storage. The size of the required interceptors was also reduced as
a result of the SWMM simulations. The sizing is based on the 1-year storm,
4.8 cm (1.9 in.) of rain.
To date, one of the storage facilities is under construction and one about to
go to bid. In each facility, as flow enters the covered structure, floating
scum and oil baffles rise with the liquid surface to maximize capture of these
materials. Depending on the magnitude of the storm, when the basin is filled,
effluent passes through horizontal screens (1.25 cm (0.49 in.) mesh) to capture
any floatable and suspended material not captured in the settling bays before
overflow to the Saginaw River. Influent to the facility is disinfected with
sodium hypochlorite. Stored flow is dewatered into the interceptor following
the storm.
The capital costs for the entire system (seven storage facilities, regulator
modification, etc.) were estimated at $44 800 000.
The storage facilities are being designed for multiple use. The two
facilities designed to date include a multistory parking garage above the
storage and treatment basin.
The actual construction cost of the Hancock Street facilities was $5 216 000
[13]. Approximately 80% of this cost is attributable to the storage facility.
The remainder is for the parking garage.
The overall performance of the facilities are estimated to be approximately
30% for BODg and 5Q% for suspended solids removal for the design storm. On
an annual basis, approximately 90% of the BODg and 92% of the suspended solids
presently discharged to the river would be removed. The basins will
completely contain approximately 1.3 cm (0.5 in.) of runoff from the tributary
area without overflowing to the river.
San Franci sco, Gal 1 form'a
Overflows occur from San Francisco's combined sewer system when rainfall
exceeds 0.05 cm/h (0.02 in./h). When rainfall exceeds this amount much of the
city's wastewater, sometime as much as 53 Mm3/yr (14 000 Mgal/yr) flows
untreated into bay and ocean waters at many points around the city.
A wastewater master plan for an improved wastewater treatment system was
developed by the Department of Public Works and its consultants between 1969
and 1974. Since 1974, parts of the plan have been changed as a result of
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further design and planning work. As the city proceeds with its 8-year
program, further changes are anticipated.
The master plan contemplates the establishment of two treatment plants; a
dry-weather flow facility in the southeastern area of the city (San Francisco
Bay side) and a combined dry- and wet-weather flow facility in the south-
western area (Pacific Ocean side). Both plants will ultimately discharge to
the ocean via a common ocean outfall system. Phase I of the plan is shown in
Figure 60 [14].
NORTH SHORE
OUTFALLS
CONSOLIDATION
NORTH
POINT
PUMPSTATION
SEWAGE
PLANT
WASTIWATER TRANSPORT/
STORAGE TUNNEL
FORCE MAIN
NORTH POINT PLANT
(CONVERSION TO INTERIM
WET IEATHER FACILITY)
CHANNEL
DUTFALLS
CONSOLIDATION
PUMP STATION
NEK fASTEWATER
OUTFALL
WEST SIDE TRANSPORT - NORTH
(RICHMOND TUNNEL ALIGNMENT
TO BE DETERMINED)
CHANNEL
PUMP
STATION
SAW FRANCISCO BAY
EXTENDED
SOUTHEAST
OUTFALL
WEST SIDE TRANSPORT
SLA1S
OUTFALLS
CONSOLIDATION
SOUTHEAST PLANT
(EXPANDED)
SLUDGE FORCE MAIN
TO SOUTHEAST PLANT
SOUTHWEST PLANT
SOUTHWEST OUTFALL
Figure 60. San Francisco wastewater
management facilities plan - Phase I.
On the ocean side, the new southwest treatment plant will replace an existing
79 500 m /s {21 Mgal/d) plant. The new plant will treat flows for the western
half of the city during wet- and dry-weather. A new outfall, presently under
design, will be constructed, which will extend out from the southwest plant
approximately 6.4 km (4 mi) offshore. Flows treated at the new plant will be
discharged to the ocean through this outfall. A large sewage
277
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transport/storage tunnel and pumping facilities will be constructed along the
west side of the city to the new plant.
Q
On the bay side, the existing 71 900 m /s {19 Mgal/d) southeast treatment
plant will be expanded to include secondary treatment facilities. The
existing capacity will be expanded to 318 000 m3/s (84 Mgal/d) to treat all
dry-weather flows for the east side of the city. The plant will also handle
sludge for the entire city. As an interim measure, the existing 260 000 m^/s
(65 Mgal/d) North Point treatment plant (dry-weather flows) will be converted
to treat wet-weather flows for the northeastern section of the city. No wet-
weather treatment facilities are proposed to handle flows from the southeast
section of the city during the initial phase of the program.
The large underground interceptor sewers that make up the North Shore,
Channel, and Islais outfalls consolidations and the West Side transport will
transport dry-weather flows to the treatment plants or pumping stations, and,
during storms, store excess wet-weather flows until they can be treated.
These facilities, with the exception of the Channel outfalls consolidation,
are expected to reduce the number of untreated combined sewer overflows to an
average of one per year. The number of overflows in the Channel outfalls area
is expected to be reduced to approximately four per year [14].
As part of the long range plan, a crosstown tunnel and expansion of the
southwest treatment plant are proposed [15]. Untreated wet-weather flows from
the northeast and southeast districts would be transported to the southwest
treatment plant 1n the crosstown tunnel. This tunnel would be designed for
both transport and storage. Treatment of wet- and dry-weather flows from the
west side and, during periods of storm runoff, excess flows from the east side
would be provided at the expanded southwest treatment plant. Wet-weather
treatment capacity at the expanded plant will be approximately 35.0 m3/s (800
Mgal/d).
The total costs for the first and second stage projects are estimated at
$513 300 000 [15]. The estimated cost for the Phase I portion is
$308 100 000. At the present time, four of ten contracts for the North Shore
and Channel outfalls consolidation projects have been awarded. The total bid
costs received for these contracts is |25 700 000 compared to the engineers
estimate of $44 750 000. The estimated cost for this entire consolidation
project is $86 420 000.
A real time automatic control computer program for inline storage and routing
control for the North Shore consolidation project is currently under
development. The objectives of this program, when ultimately applied
citywide, are: (1) minimization of overflows, (2) priority of the location
for discharges when overflows must occur, (3) make maximum use of storage
facilities, and (4) make optimal use of all facilities [16].
At present design studies for the ocean outfall, expansion and treatment
upgrading along with sludge handling at the southeast plant, facilities
planning for the new southwest plant, and the West Side transport and pumping
station are underway. A feasibility study of the crosstown tunnel is
expected to start shortly.
278
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Seattle, Washington
A comprehensive plan for the collection, treatment, and disposal of wastes
from Seattle and other communities within the drainage basin was completed in
1958. Despite improvements brought about by the basinwide construction plan,
Seattle itself was still plagued by overflows from the 60-year old combined
sewer system. A demonstration project was begun in 1967 to achieve "the
ultimate in system storage and control in a combined sewer system through
computerized 'total system management1" [17]. This resulted in the
development known as the "Computer Augmented Treatment and Disposal System,"
or CATAD.
The CATAD system is a computer-directed system for maximum utilization of
available storage in the trunk and interceptor sewers to reduce or completely
eliminate combined sewer overflows. The CATAD system utilizes a computer-
based central facility for automatic control of remote regulator and pumping
stations. The control center includes a computer, its associated peripheral
equipment, an operators console, an interceptor system map display, data
loggers, and event printers.
At the same time that the Municipality of Metropolitan Seattle (METRO) was
developing the CATAD system, the City of Seattle was proceeding with complete
or partial sewer separation projects in several areas of the city. The end
result was that the CATAD system serves approximately 5310 ha (13 120 acres)
of combined sewers. Of the city's total of 21 060 ha (52 000 acres), the
sewer separation area amounted to 7290 ha (18 000 acres).
Remote monitoring and control units were provided to 37 remote pumping and
regulator stations. In addition, six remote rain gages are also monitored.
The CATAD system can be operated in three different modes: (1) local control,
(2) supervisory control, and (3} automatic control. Under local control each
station is operated independently by controllers within the station in
response to local sensing devices. In the supervisory control mode, stations
are operated remotely from the central terminal by the operator via the CATAD
computer in response to telemetered data. Stations are operated from the
central terminal under program control by the CATAD system computer in the
automatic control mode.
Using supervisory control, the volume of overflows was reduced by 35 to B0%.
Adding automatic control strategies improved these reductions to over 901
[18]. An optimizing model is being developed that is expected to maintain a
performance of at least BQ% annual overflow volume reduction. Conclusions
reached as a result of the demonstration project include:
Loading analysis reveals that 80 to 90% of the peak loading has been
reduced, and the peak loading has been shifted to a higher rainfall rate
which occurs less frequently. Total loading in pounds has been decreased
an average of 58% for ammonia; up to 76% for COD.
Rainfall intensity has a considerable effect on overflows. Considering
the average rainfall rate of a storm, the total system reduced overflow
279
-------
volumes by 73.6% in supervisory control, 97.2% in automatic control, and 85.82
under combined advanced control modes.
Each station tended to show a "fingerprint" effect for sequential
overflow data. This fingerprint was generally unique for each station
and usually repeated itself for different storm types. The data
indicated that the first flush of materials is often diverted to the
interceptor in a combined system rather than overflowing to the receiving
water.
Overflow priorities were based primarily upon volume reduction. Station
by station priority varied considerably depending on which pollution
factor was the basis for establishing priority.
During the course of the study, the Duwamish River receiving water has
improved dissolved oxygen content by 1 to 2 milligrams per liter. [18],
The success of the application of total systems management concepts is aided
by the improved surveillance afforded by the continuous monitoring capability.
But the greatest part of the improved performance is due to the ability (under
either supervisory or automatic control) to locate portions of the sewer
system which can be utilized for storage, thereby allowing overburdened
portions of the system to flow more freely [18],
The modifications to the existing combined sewer system included combined
sewer separation work by the City of Seattle affecting about 25% of the
combined sewers in the CATAD area; modifications to and construction of
regulator and pumping stations by the City of Seattle; modification of
regulator stations required for CATAD by METRO; and acquisition and
interfacing of the telemetry system, controls, and computer for CATAD by
METRO. The total cost for the modifications and acquisitions was
|165 650 000. The cost associated with just the CATAD system (regulator
station modifications, telemetry system, and control and computer equipment)
was $8 390 000. These costs on a unit area basis were $5HO/ha and $260/ha
($12 625/acre and $640/acre), respectively.
The Woodlands, Texas
A new town, The Woodlands, is under development 56 km (35 mi) north of
Houston, Texas. The town will contain all services of a modern city,
including facilities for social, recreational, education, commercial,
institutional, business, and industrial pursuits. When development began in
1972, the 7200 ha (17 780 acres) was just heavy forest. Development will span
20 years and lead to homes for approximately 150 000 people.
The basic drainage system planned for The Woodlands was designed on the basis
of what was termed the "natural drainage" concept. This concept consists of
the following principles:
(a) the existing drainage system in its unimproved state is utilized to
the fullest extent possible; (b) where drainage channels need to be
constructed, wide, shallow swales lined with existing vegetation are used
280
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instead of cutting narrow, deep ditches; (c) drainage pipes and other
flood control structures are used only where the natural system is
inadequate to handle increased urban runoff, such as in high-density
urban activity centers; and (d) flow retarding devices such as retention
ponds and recharge berms are used where practical to minimize increases
in runoff volume and peak flow rates due to development. [19]
It was originally estimated that utilizing the "natural drainage" concept
would keep the drainage system costs down to about 50% of that for
conventional systems. As part of the initial planning, the impact of the
planned urbanization in The Woodlands community was evaluated using the Storm
Water Management Model (SWMM). The results were used to develop a program to
minimize impact of further development.
To minimize the amount and rate of increased runoff due to urbanization,
existing drainage courses are grass covered to slow and reduce runoff through
infiltration. Storage reservoirs are used to promote recharge of groundwater
and attenuate runoff. Examples of the use of natural drainage features and
storage reservoirs are shown in Figure 61. Erosion control measures in
construction areas minimize solids loadings in runoff from these areas. The
type and amount of fertilizers, pesticides, and herbicides are controlled to
minimize pollution of runoff [20],
The Woodlands terrain in many places is quite flat. In a recent review it was
reported that in such spots, natural drainage has been found to cause flooding
of homesltes [21]. Also, Houston area officials dislike the natural drainage
idea—drainage swales and ditches accumulate debris and silt, and bushes grow
there. Removing the debris and bushes is a maintenance cost. These officials
feel sewers are less of a problem. The goal is still to use natural drainage
wherever practical, but to balance ecology with practical economics since no
one wants to live on flooded land.
Part of the original intent was to provide multifamily and cluster housing to
keep the developed land to a minimum, thus minimizing the increased runoff
from urbanization. However, many Houstonians who can afford new housing want
single-family housing [21]. This may result in a smaller percentage of The
Woodlands land left in open space than was originally planned. This would
most likely increase the amount and rate of runoff.
SUMMARY
From the case studies presented and summarized in Table 123, it is apparent
that all use an integrated approach toward solving the stormwater pollution
problems. The programs developed by communities with combined sewers
generally rely on structural methods to solve the overflow problems. For
communities with separate sewers, the stormwater abatement programs
incorporate both best management practices and structural solutions. This
difference in approaches is probably best explained by comparing the types
of communities with combined or separate sewers.
Most of the combined sewers are found in the older, highly urbanized cities.
As a result, the more easily implementable and least costly best management
281
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(b)
(c)
Figure 61. Natural drainage and storage reservoir, The Woodlands, Texas.
(a) and (b) Natural drainage swales, (c) Stormwater storage basin used
as a recreational reservoir in planned development.
282
-------
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practices such as onsite retention, erosion control, use of pervious areas for
percolation, and use of natural drainage features to attenuate runoff are
difficult, if not Impossible, to apply. Thus, reliance on structural methods
such as storage and treatment is necessary. Separate sewers may be found in
the newer portions of some old cities and in suburban communities. In these
areas, best management practices are usually more easily implemented.
Incorporating best management practices into the stormwater abatement program
generally reduces the need for structural solutions.
It is noteworthy that all of the programs incorporate storage in one form or
another. This allows a greater stormwater volume to be treated than just
relying on the interceptor capacity to convey stormwater to a treatment plant.
In most cases, inline storage is included; even where offline storage is used.
This allows the stormwater to be treated using the excess capacity at
existing treatment plants or allows the use of smaller new treatment plants.
The unit capital costs for the programs range from $1780/ha to $8660/ha
($4400/acre to $21 375/acre) for communities with combined sewers. There are
insufficient data to determine a similar range of costs for communities with
separate sewers. Direct comparison of the unit costs for the sewer separation
and collection/treatment options for Mount Clemens should not be made since
separation is being done in an area that is primarily industrial and open
space. The costs for collection and treatment of the combined sewer overflows
(in areas where this option was selected) were approximately 30 to 601 of the
cost for sewer separation in the same areas.
285
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REFERENCES
SECTION T
1. Lager, J. A., etal< Catchbasin Technology Overview and Assessment.
USEPA Report No. EPA-6QQ/2-77-051 . May 1977.
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Construction Grants Program for Municipal Wastewater Treatment Works.
Revised TM 76-1. August 1976.
3. Sullivan, R. H., etal. Nationwide Evaluation of Combined Sewer
Overflows and Urban Stormwater Discharges, Volume I: Executive
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SECTION 2
1. Lager, J. A. and W. G. Smith. Urban Stormwater Management and Tech-
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S1CTION 3
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for Optimum Design and Control of Metropolitan Wastewater Management
Systems. Water Resources Bulletin. 9(6):1188-1200, December 1973.
28. Huber, W. C., etal. Storm Water Management Model User's Manual Version
II. USEPA Report No. EPA-670/2-75-017. March 1975.
289
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29. Mevius, F. Analysis of Urban Sewer Systems by Hydrograph-Volume Method.
Paper Presented at the National Conference on Urban Engineering Terrain
Problems, Montreal, Canada, May 1973.
30. Geiger, F. W. Urban Runoff Pollution Derived From Long-Time Simulation.
Paper Presented at the National Symposium on Urban Hydrology and Sedi-
ment Control, Lexington, Kentucky, July 28-31, 1975.
31. Shubinski, R. P. and L. A. Roesner. Linked Process Routing Models.
Paper Presented at American Geophysical Union Annual Spring Meeting,
Washington, D.C., April 1963.
32. Leiser, C. P. Computer Management of a Combined Sewer System. USEPA
Report No. EPA-670/2-74-022. NTIS No. PB 235 717. July 1974.
33. Grimsrud, G. P., eta!. Evaluation of Water Quality Models: A Manage-
ment Guide for Planners. USEPA Report No. EPA-600/5-76-004. NTIS No.
PB 256 412. July 1976.
34. Finnemore, E. J. and G. P. Grimsrud. Evaluation and Selection of Water
Quality Models: A Planner's Guide. {In: Proceedings of the Conference
on Environmental Modeling and Simulation, Cincinnati, Ohio, April 19-22,
1976.) USEPA Report No. EPA-600/9-76-916. NTIS No. PB 257 142. July
1976.
35. Metcalf & Eddy, Inc. Wastewater Engineering and Management Plan for
Boston Harbor-Eastern Massachusetts Metropolitan Area. Technical Data.
Volume 7, Combined Sewer Overflow Regulation, Metropolitan District
Commission. November 1975.
36. U.S. Department of Commerce, Weather Bureau. Technical Paper No. 40.
Rainfall Frequency Atlas of the United States, January 1963.
SECTION 5
1. Sartor, J. D. and G. B. Boyd. Water Pollution Aspects of Street Sur-
face Contaminants. USEPA Report No. EPA-R2-72-Q81. NTIS No.
PB 214 408. November 1972.
2. Weibel, S. R., R. J. Anderson, and R. L. Woodward. Urban Land Runoff
As a Factor in Stream Pollution. Journal of the Water Pollution
Control Federation. 36:914-924, July 1964.
3. Brunner, P. G. The Pollution of Storm Water Runoff in Separate Systems:
Studies With Special Reference to Precipitation Conditions in the Lower
Alp Region. Water Resources and Sanitary Engineering Dept. of Munich
Technical University. 1975. (German Translation).
4. Shaheen, D. G. Contributions of Urban Roadway Usage to Water Pollution.
USEPA Report No. 600/2-75-004. NTIS No. PB 245 854. April 1975.
290
-------
Heaney, J.P., et al. Urban Stormwater Management Modeling and Decision-
Making. USEPA Report No. EPA-67Q/2-75-022. NTIS No. PB 242 290.
May 1975.
Manning, M. J,, et al. Nationwide Evaluation of Combined Sewer Over-
flows and Urban Stormwater Discharges, Volume III: Characterization of
Discharges. USEPA Report No. 600/2-77-064c. At Press.
American Public Works Association, Water Pollution Aspects of Urban
Runoff. USEPA Report No. 11030DNS01/69. NTIS No. PB 215 532.
January 1969.
Amy, G., et al . Water Quality Management Planning for Urban Runoff.
USEPA Report No. EPA 440/9-75-004. 'riTIS No. PB 241 689. December 1974.
9. McElroy, A. D., et al . Loading Functions for Assessment of Water Pol-
lution From Nonpoint Sources. USEPA Report No. EPA-600/2-76-151 . NTIS
No. PB 253 325. May 1976.
10. Black, Crow & Edisness, Inc., and Jordan, Jones & Goulding, Inc. Non
Point Pollution Evaluation Atlanta Urban Area. Contract No. DACW 21-74-
C-0107. May 1975.
11. Davis, P. L. and F. Borchardt. Combined Sewer Overflow Abatement Plan,
Des Moines, Iowa. USEPA Report No. EPA-R2-73-17Q. April 1974.
12. Colston, N. V., Jr. Characterization and Treatment of Urban Land Run-
off. USEPA Report No. EPA-670/2-74-096. NTIS No. PB 240 978.
December 1974.
13. Betson, Roger. Urban Hydrology: A Systems Study in Knoxville, Ten-
nessee. Tennessee Valley Authority. June 1976.
14. AVCO Economic Systems Corporation. Storm Water Pollution From Urban
Land Activity. USEPA Report No. 11034FKL07/70. NTIS Mo. PB 195 281.
July 1970.
15. Mason, D. 6., et _aj_. Screening/Flotation Treatment of Combined Sewer
Overflows. Volume I: Bench Scale and Pilot Plant Investigations.
USEPA Report No. EPA-600/2-77-069a. 1977. At Press.
16. Proposed UHR Filtration Pilot Plant Test Program on Combined Sewer
Storm Overflows and Raw Dry Weather Sewage at New York City's Newtown
Creek Sewage Treatment Plant. USEPA Demonstration Grant No. S-803271 .
May 1975. Draft.
17. Feuerstein, D. L. and W. 0. Maddaus. Wastewater Management Program,
Jamaica Bay, New York. Volume I; Summary Report; Volume II: Supple-
mental Data, New York City Spring Creek. USEPA Report Nos. EPA-600/2-
76-222a and EPA-600/2-76-222b. NTIS Nos. PB 260 887 and PB 258 308.
September 1976.
291
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18. Coyne & Bellier Consulting Engineers. Measurements and Evaluation of
Pollution Loads From a Combined Sewer Overflow. General Report and
Annex 1 Through 4. Ministry of the Environment; Ministry of Public
Works. March 1974. (French Translation).
19. Clark, M. 0., et al. Screening/Flotation Treatment of Combined Sewer
Overflows, Volume I! - Full-Scale Demonstration. USEPA Demonstration
Grant No. 11023FWS. April 1975. Draft Report.
20, Lager, J. A., et a1_. Development and Application of a Simplified
Stormwater Management Model. USEPA Report No. EPA-600/2-76-218.
NTIS No. PB 258 074. August 1976.
21. City of Milwaukee, Wisconsin, and Consoer, Townsend and Associates.
Detention Tank for Combined Sewer Overflow, Milwaukee, Wisconsin,
Demonstration Project. USEPA Report No. EPA-600/2-75-071. NTIS No.
PB 250 427. December 1975.
22. Huber, W. C. and J. P. Heaney. Urban Rainfall-Runoff-Quality Data
Base. USEPA Reoort No. EPA-600/8-77-009. July 1977.
23. Metcalf & Eddy, Inc. Wastewater Engineering: Collection, Treatment,
Disposal. McGraw-Hill, Inc., New York. 1972.
24. Klein, L. A., et_a_K Sources of Metals in New York City Wastewater.
Journal of the Water Pollution Control Federation. 46-2653-2662,
December 1974.
25. U.S. Dept. of the Interior, Geological Survey. Water Resources Data
For California, Part 2, Water Quality Records, 1972.,
26. Olivieri, V. P., et al. Microorganisms in Urban Stormwater. USEPA
Report No. EPA-6QO/2-77-Q87. At Press.
27. Davis, E. M. Maximum Utilization of Water Resources in a Planned Com-
munity: Bacterial Characteristics of Stormwaters in Developing Rural
Areas. USEPA Research Grant R-802433. 1976. Draft Report.
28. Condon, F. J. Methods of Assessment of Non-Point Runoff Pollution.
The Dipi ornate. December 1973.
29. Sullivan, R. H., et al. Nationwide Evaluation of Combined Sewer Over-
flows and Urban Stormwater Discharges, Volume I: Executive Summary.
USEPA Report No, EPA-600/2-77-064a. At Press.
30. Areawide Assessment Procedures Manual, Volumes I and II. U.S.
Environmental Protection Agency. EPA-600/9-76-014. July 1976.
31. Coyne & Bellier Consulting Engineers. Study for Creteil's Lake
Protection. June 1976. {French Translation).
292
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32. Underwater Storage, Inc., and Silver, Schwartz, Ltd. Control of Pol-
lution by Underwater Storage, USEPA Report No. 11020DWF12/69. NTIS No.
191 217. December 1969.
33. Roy F. Weston, Inc. Combined Sewer Overflow Abatement Alternatives,
Washington, D.C. USEPA Report Ho. 11024EXF03/70. NTIS No. PB 203 680.
August 1970.
34. Metcalf & Eddy, Inc., University of Florida, and Water Resources Engi-
neers, Inc. Storm Water Management Model, Volume I. USEPA'Report No.
11024DOC07/71. NTIS No. PB 203 289. July 1971.
35. Gupta, M. K., e t a 1. Handling and Disposal of Sludges Arising From Com-
bined Sewer Overflow Treatment - Phase 1 - Characterization. USEPA
Report No. EPA-600/2-77-053a. May 1977.
36. Clark, M. J, and A. Geinopolos. Assessment of the Impact of the Hand-
ling and Disposal of Sludges Arising From Combined Sewer Overflow
Treatment. USEPA Contract No. 68-03-0242. February 1976. Draft
Report.
37. Poon, C. P. C. and K. H. Bhayani. Metal Toxicity to Sewage Organisms.
Journal of the Sanitary Engineering Division, ASCE. 97:161-169, April
1971.
38. Barth, E. F., M. B. Ettinger, B. V. Salotto, and G. N. McDermott. Sum-
mary Report on the Effects of Heavy Metals on Biological Treatment Pro-
cesses. Journal of the Water Pollution Control Federation, 37:86-
96, January 1965.
39. Nemerow, N. L. Liquid Waste of Industry: Theories, Practices and
Treatment. Addison-Wesley, Menlo Park, California. 1971.
40. McCarty, P. L., I. J. Kugelman, and A. W. Lawrence. Ion Effects in
Anaerobic Digestion. Dept. of Civil Engineering, Stanford University.
Technical Report No. 33. March 1964.
41. Proceedings of the Urban Stormwater Management Seminars, Atlanta,
Georgia, November 4-6, 1975, and Denver, Colorado, December 2-4, 1975.
USEPA Report No. WPD 03-76-04. NTIS No. PB 260 889.
42. Geldreich, E. E. and B. A. Kenner. Concepts in Fecal Streptococci in
Stream Pollution. Journal of the Water Pollution Control Federation.
41:R336-R352. August 1969.
43. Waite, T. D. and L. J. Greenfield. Stormwater Runoff Characteristics
and Impact on Urban Waterways. (Prepublication Copy).
44. Kluesener, J. W. and G. F. Lee. Nutrient Loading From a Separate Storm
Sewer in Madison, Wisconsin. Journal of the Water Pollution Control
Federation. 46:920-936, May 1974.
293
-------
45, Lager, J. A. and W, 6, Smith. Urban Stormwater Management and Tech-
nology, an Assessment. USEPA Report No. EPA-670/2-74-Q40. NTIS No.
PB 240 687. December 1974.
46. Harper, M. E., et al. Degradation of Urban Streams From Stormwater
Runoff. Presented at the ASCE Environmental Engineering Division
Specialty Conference, Gainesville, Florida, July 20-23, 1975. Draft.
SECTION 6
1. Thelen, E., et aj. Investigation of Porous Pavements for Urban Runoff
Control. USEPA Report No. 11034DUY03/720. NTIS No. PB 227 516.
March 1972.
2. Everhart, R. C. New Town Planned Around Environmental Aspects. Civil
Engineering - ASCE. September 1973.
3. Bhutani, J., et al. Impact of Hydro!ogic Modifications on Water Qual-
ity. USEPA Report No. EPA-600/2-75-007. NTIS No. PB 248 523. April
1975.
4. Task Committee on the Effects of Urbanization on Low Flow, Total Runoff,
Infiltration, and Ground-Water Recharge of the Committee on Surface-
Water Hydrology of the Hydraulics Division. Aspects of Hydrological
Effects of Urbanization. Journal of the Hydraulics Division, ASCE. 101:
444-468, May 1975.
5. Syrek, Daniel B. California Litter: A Comprehensive Analysis and Plan
for Abatement. Institute for Applied Research, Carmichael, California.
May 1975.
6. American Public Works Association. Water Pollution Aspects of Urban
Runoff. USEPA Report No. 11030DNS01/69. NTIS No. PB 215 532. January
1969.
7. Sartor, J. D. and S. B. Boyd. Water Pollution Aspects of Street Sur-
face Contaminants. USEPA Report No. EPA-R2-72-081. NTIS No. PB
214 408. November 1972.
8. Amy, G., et al. Water Quality Management Planning for Urban Runoff.
USEPA Report No. EPA 440/9-75-004. NTIS No. PB 241 689. December 1974.
9. McPherson, M. B. Utility of Urban Runoff Modeling. In: Proceedings of
a Special Session, Spring Annual Meeting, American Geophysical Union,
Washington, D.C., April 14, 1976. ASCE Urban Water Resources Research
Program, Technical Memorandum No. 31, July 1976. Draft.
10. Field, R. and J. A. Lager. Countermeasures for Pollution From Over-
flows. The State of the Art. USEPA Report No. EPA-670/2-74-090. NTIS
No. PB 240 498. December 1974.
294
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11. McCuen, R. H. Flood Runoff From Urban Areas. Office of Water Research
and Technology. Technical Report No. 33. June 1975.
12. Heaney, J. P., et al. Storm Water Management Model: Level I - Prelim-
inary Screening Procedures. USEPA Report No. EPA-600/2-76-275. NTIS
No. PB 259 916. October 1976.
13. Casey, J. R. Our Crash Street-Cleaning Program...Covers Every Street
in the City in Five Days. The American City. July 1970.
14. Levis, A. H. Urban Street Cleaning. USEPA Report No. EPA-670/2-75-030.
NTIS No. PB 239 327.
15. Murray, D. M. and U. F. W. Ernst. An Economic Analysis of the Environ-
mental Impact of Highway Deicing. USEPA Report No. EPA-600/2-76-105.
NTIS No. PB 253 268. May 1976.
16. Field, Richard, et al. Water Pollution and Associated Effects From
Street Salting. USEPA Report No. EPA-R2-73-257. NTIS No. 222 795.
May 1973.
17. Edison Water Quality Laboratory, Edison, New Jersey. Environmental
Impact of Highway Deicing. USEPA Report No. 11040GKK06/71. NTIS No.
203 493. June 1971.
18. Lager, J. A. and W. G. Smith. Urban Stormwater Management and Tech-
nology, an Assessment. USEPA Report No. EPA-670/2-74-040. NTIS No.
PB 240 687. December 1974.
19. Murray, D. M., and M. R. Eigerman. A Search: New Technology for Pave-
ment Snow and Ice Control. USEPA Report No. EPA-R2-72-125. NTIS No.
PB 221 250. December 1972.
20. Mammel, F. A. We Are Using Salt - Smarter. The American City.
January 1972.
21. Metcalf, L. and H. P. Eddy. American Sewerage Practice, Volume I, 2nd
Edition. McGraw-Hill, Inc., New York. 1928^
22. American Public Works Association. Survey of Practice as to: Street
Cleaning Catch Basin Cleaning, Snow and Ice Control. March 1973.
23. San Francisco Master Plan for Waste Water Management, Preliminary Com-
prehensive Report. City and County of San Francisco, Department of
Public Works. September 1971.
24. Metcalf & Eddy, Inc., University of Florida, and Water Resources Engi-
neers, Inc. Storm Water Management Model, Volume I. USEPA Report No.
11024DOC07/71. NTIS No. PB 203 289.
25. Lager, J. A., et al. Catchbasin Technology Overview and Assessment.
USEPA Report No. EPA-600/2-77-051. May 1977.
295
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26. Handbook for Sewer System Evaluation and Rehabilitation. USEPA Report
No. EPA-430/9-75-021. December 1975.
27. Pisano, W. C. Cost Effective Approach for Combined and Storm Sewer
Clean-Up. (In: Proceedings of Urban Stormwater Management Seminars.)
USEPA Report No. WPD 03-76-04. NTIS No. PB 260 889. January 1976
28, Process Research Inc. A Study of Pollution Control Alternatives for
Dorchester Bay. Commonwealth of Massachusetts Metropolitan District
Commission. Volumes 1, 2, 3, and 4. December 23, 1974.
29. Cesareo, D. J., and R, Field. Infiltration-Inflow Analysis, Journal
of the Environmental Engineering Division, ASCE. 101(5):775-784»
October 1975.
30. Poertner, H. G. Practices in Detention of Urban Stormwater Runoff, an
Investigation of Concepts, Techniques, Applications, Costs, Problems,
Legislation, Legal Aspects and Opinions. APWA. Special Report No. 43.
1974.
31. Poertner, H. 6. Urban Stormwater Detention and Flow Attenuation for
Water Pollution Control. (In: Proceedings of Urban Stormwater Manage-
ment Seminars.) USEPA Report No. WPD 03-76-04. NTIS No. PB 260 889.
January 1976.
32. Debo, T, N. Survey and Analysis of Urban Drainage Ordinances and a
Recommended Model Ordinance. Environmental Resources Center and Georgia
Institute of Technology. ERC-0475. February 1975.
33. USEPA Contact: Mr. Dennis N. Athyade, Office of Water and Hazardous
Materials, Water Planning Division, 401 M Streel S.W., Waterside Mall,
Washington, D.C. 20460.
SECTION 7
1. Field, R. and J. A. Lager. Countermeasures for Pollution From Over-
flows: The State of the Art. USEPA Report No. EPA-670/2-74-090. NTIS
No. PB 240 498. December 1974.
2. Lager, J. A. and W. G. Smith. Urban Stormwater Management and Tech-
nology, an Assessment. USEPA Report No. EPA-670/2-74-040. NTIS No,
PB 240 687. December 1974.
3. Heaney, J. P., e_t al_. Nationwide Evaluation of Combined Sewer Over-
flows and Urban Stormwater Discharges, Volume II: Cost Assessment and
Impacts, USEPA Report No. EPA-600/2-77-064. NTIS No. PB 266 005.
March 1977.
4. Heaney, J. P., et aT_. Storm Water Management Model: Level I - Prelim-
inary Screening Procedures. USEPA Report No. EPA-6QO/2-76-275. NTIS
No. PB 259 916. October 1976.
296
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5. Leiser, C. P. Computer Management of a Combined Sewer System. USEPA
Report No. EPA-67Q/2-74-022. NTIS No. PB 235 717. July 1974.
6. Metropolitan Sewer Board - St. Paul, Minnesota. Dispatching System for
Control of Combined Sewer Losses. USEPA Report No. 11020FAQ03/71. NTIS
No. PB 203 678. March 1971.
7. Watt, T. R., et al. Sewerage System Monitoring and Remote Control.
USEPA Report No. EPA-670/2-75-02Q. NTIS No. PB 242 107. May 1975,
8. Grigg, N. S., J. W. Labadie, G. L. Smith. D. W. Hull, and B. H.
Bradford. Metropolitan Water Intelligence Systems Completion Report -
Phase II. U.S. Department of the Interior, Office of Water Resources
Research. Colorado State University, Fort Collins. Grant No. 14-31-
0001-3685. Water Resources Systems Program. June 1973.
9. Grigg, N. S., J. W. Labadie, and H, S. Wenzel. Metropolitan Water
Intelligence Systems Completion Report - Phase III. U. S. Department
of the Interior, Office of Water Resources Research. Colorado State
University, Fort Collings. Grant No. 14-31-0001-9028. Water Resources
Systems Program. June 1974.
10. Labadie, J. W., N. S. Grigg, and B. H. Bradford. Automatic Control of
Large-Scale Combined Sewer Systems. Journal of the Environmental Engi-
neering Division, ASCE. 101(1):27-39, February 1975.
11. U.S. Environmental Protection Agency, and Booz, Allen and Hamilton Inc.
Draft Environmental Impact Statement, Tunnel Component of the Tunnel and
Reservoir Plan Proposed by the Metropolitan Sanitary District of
Greater Chicago; Mainstream Tunnel System, 59th Street to Addison
Street. March 1976.
12. Dodson, Kinney, and Lindblom. Evaluation of Storm Standby Tanks,
Columbus, Ohio. USEPA Report No. 11020FAL03/71. NTIS No. PB 202 236.
March 1971.
13. City of Milwaukee, Wisconsin, and Consoer, Townsend and Associates.
Detention Tank for Combined Sewer Overflow, Milwaukee, Wisconsin,
Demonstration Project. USEPA Report No. EPA-600/2-75-071. NTIS
No. PB 250 427. December 1975.
14. Mel par - An American-Standard Company. Combined Sewer Temporary
Underwater Storage Facility. USEPA Report No. 11022DPP10/70. NTIS No.
PB 197 669. October 1970.
15. Underwater Storage, Inc., and Silver, Schwartz, Ltd. Control of Pol-
lution by Underwater Storage. USEPA Report No. 11020DWF12/69. NTIS
No. PB 191 217. December 1969.
16. Karl R. Rohrer Associates, Inc. Underwater Storage of Combined Sewer
Overflows. USEPA Report No. 11022ECV09/71. NTIS No. PB 208 346.
September 1971.
297
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17. Commonwealth of Massachusetts, Metropolitan District Commission.
Cottage Farm Combined Sewer Detention and Chiorination Station, Cam-
bridge, Massachusetts. USEPA Report No. EPA-600/2-77-046. NTIS No.
PB 263 292. November 1976.
18. Liebenow, W. R. and J. K. Bieging. Storage and Treatment of Combined
Sewer Overflows. USEPA Report No. EPA-R2-72-070. NTIS No. PB 214 106.
October 1972.
19. Environmental Assessment Statement for Charles River Marginal Conduit
Project in the Cities of Boston and Cambridge, Massachusetts. Common-
wealth of Massachusetts, Metropolitan District Commission. September
1974.
20. Lynard, W. G. Trip Report; Oil City and Franklin, Pennsylvania, and
Boston, Massachusetts. May 5, 1976.
21. Karl R. Rohrer Associates, Inc. Demonstration of Void Space Storage
With Treatment and Flow Regulation. USEPA Report No. EPA-600/2-76-272.
NTIS No. PB 263 032. December 1976.
22. Feuerstein, D. L. and H. 0. Maddaus. Wastewater Management Program,
Jamaica Bay, New York; Volume II; Supplemental Data, New York City
Spring Creek. USEPA Report No. EPA-60Q/2-76-222b, NTIS No. PB 258 308.
September 1976.
23. Lynard, W. G. Trip Report; Denver, Chicago, Kenosha, Racine, Mil-
waukee, Toronto, and New York City. June 21-25, 1976.
24. City of New York Environmental Protection Administration. Spring Creek
Auxiliary Water Pollution Control Plant Operational Data, January 1974
to January 1976,
25. Feuerstein, P. L. and W. 0. Maddaus. Wastewater Management Program,
Jamaica Bay, New York; Volume I: Summary Report. USEPA Report No.
EPA-600/2-76-222a. NTIS No. PB 260 887. September 1976.
26. Development of a Flood and Pollution Control Plan for the Chicago!and
Area. Metropolitan Sanitary District of Greater Chicago, Institute for
Environmental Quality, State of Illinois, and Department of Public
Works, City of Chicago. August 1972.
27. Benjes, H. H., Jr. Cost Estimating Manual - Combined Sewer Overflow
Storage Treatment. USEPA Report No. EPA-600/2-76-286. NTIS No. 266
359. December 1976.
28. Allen, D. M., et &1. Treatment of Combined Sewer Overflows by High
Gradient Magnetic Separation. USEPA Report No. EPA-600/2-77-015. NTIS
No. PB 264 935, March 1977.
298
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29. Sullivan, R. H., et al. Relationship Between Diameter and Height for
the Design of a Swirl Concentrator as a Combined Sewer Overflow Regu-
lator. USEPA Report No. EPA-670/2-74-039. NTIS No. PB 234 646. July
1974.
30. Sullivan, R. H., et al. The Helical Bend Combined Sewer Overflow Regu-
lator. USEPA Report No. EPA-600/2-75-062. NTIS No. PB 250 619.
December 1975.
31. Process Design Manual for Suspended Solids Removal. U.S. Environmental
Protection Agency, Technology Transfer. USEPA Report No. 625/1~75-003a.
January 1975.
32. Ripkin, J. F., et a_l. Methods for Separation of Sediment From Storm
Water at Construction Sites. USEPA Report No. EPA-600/2-77-033. NTIS
No. PB 262 782.
33. Wolf, H. W. Bachman Treatment Facility for Excessive Storm Flow in
Sanitary Sewers. USEPA Report No. EPA-600/2-77-128.
34. Metea If & Eddy, Inc. Saginaw, Michigan, Combined Sewer Overflow Abate-
ment Plan - Preliminary Design Report (March 1973), and Hancock Steet
Facility Bid Tabulation (September 1976).
35. O'Brien & Gere, Engineers. Disinfection/Treatment of Combined Sewer
Overflows-Syracuse, N.Y. Demonstration Grant No. S-802400. March 1977.
Draft Report.
36. O'Brien & Gere, Engineers. Combined Sewer Overflow Abatement Program,
Rochester, N.Y. Grant No. Y-005141. November 1976. Draft Report.
37. Lancaster Silo Project-Post Construction Evaluation Plan. USEPA
Demonstration Grant No. S-802219 (formerly 11023 GSC). 1973. Draft.
38. Sullivan, R. H., et aJN Field Prototype Demonstration of the Swirl
Degritter. USEPAlFant No. S-803157. August 1976. Draft Report.
3D. Sullivan, R. H., et al. The Swirl Primary Separator: Development and
Pilot Demonstration. USEPA Demonstration Grant No. S-803157. December
1976. Draft Report.
40. Sullivan, R. H., et al. The Swirl Concentrator for Erosion Runoff
Treatment. USEPA Report No. EPA-600/2-76-271. NTIS No. PB 266 598.
September 1975.
41. Design Alternatives and Construction Drawings for Lancaster, Pennsyl-
vania Swirl Project. USEPA Demonstration Grant No. S-802219. November
1976.
42. Field,. R, I. Treatability Determinations for a Prototype Swirl Com-
bined Sewer Overflow Regulator/Sol ids-Separator. (USEPA Demonstration
299
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Grant No. S-802400.) In: Proceedings of the Urban Stormwater Manage-
ment Seminars, Atlanta, Georgia, November 4-6, 1975, and Denver,
Colorado, December Z-4, 1975. USEPA Report No. WPO 03-76-04. NTIS No.
PB 260 889. January 1976.
43. Clark, M. J., et a!. Screening/Flotation Treatment of Combined Sewer
Overflows, Volume II: Full-Scale Demonstration, USEPA Demonstration
Grant No. 11023 FWS. Draft Report. April 1975.
44. Mason, D. G,, et al. Screening/Flotation Treatment of Combined Sewer
Overflows. Volume !: Bench Scale and Pilot Plant Investigations.
USEPA Report No. EPA-600/2-77-069a. 1977. At Press.
45. Bursztynsky, T. A., et a]. Treatment of Combined Sewer Overflows by
Dissolved Air Flotation. USEPA Report No. EPA-600/2-75-033. NTIS No.
PB 248 186. September 1975.
46. Proposed UHR Filtration Pilot Plant Test Program on Combined Sewer
Storm Overflows and Raw Dry Weather Sewage at New York City's Newtown
Creek Sewage Treatment Plant. USEPA Demonstration Grant No. S-803271.
May 1975. Draft.
47. Nebolsine, R., et al. High Rate Filtration of Combined Sewer Overflows.
USEPA Report No. 11023EYI04/72. NTIS No. PB 211 144. April 1972.
48. Operational Data for the Belleville Screening Project. Ontario
Ministry of the Environment. August 6, 1976.
49. Lynard, W. G. Memorandum for the Record. Status Report on Four Storm-
water Treatment Facilities (Norwalk, Euclid, Oil City, and Flint).
September 11, 1975.
50. Prah, D. H. and P. L. Brunner. Combined Sewer Stormwater Overflow
Treatment by Screening and Terminal Ponding at Fort Wayne, Indiana.
USEPA Demonstration Grant No. 11020 GYU. Volumes 1 and 2. June 1976.
Draft Report.
51. Clark, M. J., T. L. Meinholz, and C. A. Hansen. Screening/Dissolved-
Air Flotation With Powdered Activated Carbon Addition for the Treatment
of Combined Sewer Overflows. Wisconsin Department of Natural Resources.
Madison, Wisconsin. Project No. 8110. March 1975.
52. Mahida, V. U. and F, J. Dedecker. Multi-Purpose Combined Sewer Overflow
Treatment Facility, Mount Clemens, Michigan. USEPA Report No. EPA-670/
2-75-010. NTIS No. PB 242 914. May 1975.
53. Environmental Protection Administration, Department of Water Resources,
City of New York. Ultra High Rate Filtration Study. Progress Report
No. 5. USEPA Demonstration Grant No. S-803271. October-November 1976.
54. Lynard, W. G. Trip Report; Chicago, Ft. Wayne, and Syracuse.
Screening Facilities. October 9, 1975.
300
-------
55. Maher, M. B. Microstraining and Disinfection of Combined Sewer Over-
flows - Phase III. USEPA Report No. EPA-670/2-74-049. NTIS No. PB
235 771. August 1974.
56. Glover, G. E. and P. M, Yatsuk. Microstraining and Disinfection of
Combined Sewer Overflows. USEPA Report No. 11023EV006/70. NTIS No. PB
195 674. June 1970.
57. Glover, G. E. and G. R. Herbert. Microstraining and Disinfection of
Combined Sewer Overflows - Phase II. USEPA Report No. EPA-R2-73-124.
NTIS No. PB 219 879. January 1973.
58. O'Brien & Gere, Engineers. Nutrient Removal Using Existing Combined
Sewer Overflow Treatment Facilities. USEPA Demonstration Grant No.
S-802400. September 1976. Draft Report.
59. Charles, Carl 0. A. Mathematical Model of a Filtration Plant. Storm and
Combined Sewer Section. USEPA, Edison, N.J. 197f. Craft.
60. Nebolsine, R., P. J. Harvey, and C. Y. Fan. Ultra High Rate Filtration
System for Treatment of Combined Sewage Overflows. Hydrotechnic Cor-
poration, Consulting Engineers. Presented at the Water Pollution
Control Federation Conference, San Francisco, October 1971.
61. Nebolsine, R. and J. C. Eck. Advanced Pollution Control Technology for
Tertiary Treatment of Sewage. Hydrotechnic Corporation, Consulting
Engineers. Presented Before the Annual Meeting of the New York Water
Pollution Control Association. USEPA Project No. 17030 HMM. January
1972.
62, Shelley, P. E. and G. A. Kirkpatrick. Sewer Flow Measurement: A State-
of-the-Art Assessment. USEPA Report No. EPA-600/2-75-027. NTIS No.
PB 250 371. November 1975.
63. Shelley, P. E. and G. A. Kirkpatrick. An Assessment of Automatic Sewer
Flow Samplers - 1975. USEPA Report No. EPA-600/2-75-065. NTIS No. PB
250 987. December 1975.
64. Wullschleger, R. E., et al. Methodology for the Study of Urban Storm-
Generated Pollution and Control. USEPA Report No. EPA-600/2-76-145.
NTIS No. PB 258 743. August 1976.
65. Neketin, T. H, and H. K. Dennis, Jr. Demonstration of Rotary Screening
for Combined Sewer Overflows. USEPA Report No. 11023FDD07/71. NTIS
No. PB 206 814. July 1971.
66. Personal Communication. Newtown Creek, New York City, New York. High
Rate Filtration of Combined Sewer Overflows. Operation of Discostrainer
as a Pretreatment Device. November 1976.
301
-------
67. Field, R. Design of a Combined Sewer Overflow Regulator/Concentrator.
Journal of the Water Pollution Control Federation. 46:1722-1741,
July 1974.
68. Sullivan, R. H., et a!. The Swirl Concentrator as a Grit Separator
Device. USEPA Report No. EPA-670/2-74-026. NTIS No. PB 233 964. June
1974.
69. Field, R. I, and P. E, Moffa. Treatability Determinations for a Proto-
type Swirl Combined Sewer Overflow Regulator/Solids-Separator.
Prog. Wat. Tech. 8(6):81-91, Pergammon Press (GB). 1977.
70. Cornell, Howland Hayes and Merryfield. Rotary Vibratory Fine
Screening of Combined Sewer Overflows. USEPA Report No.
110234FDD03/70. NTIS No. PB 195 168. June 1974.
71. Welsh, F. L, and D. J, Stucky. Combined Sewer Overflow Treatment by the
Rotating Biological Contactor Process. USEPA Report No. EPA-670/2-74-
050. NTIS No. 231 892. June 1974.
72. Agnew. R, W.s etal. Biological Treatment of Combined Sewer Overflow
at Kenosha, Wisconsin. USEPA Report No. EPA-670/2-75-019. NTIS No.
n PB 242 126. April 1975.
73. Hamack, P., et a 1. Utilization of Trickling Filters for Dual-Treatment
of Dry and Wet-Weather Flows. USEPA Report No. EPA-670/2-73-071. NTIS
No. PB 231 251. September 1973,
74. Parks, J. W., ejt_a]_. An Evaluation of Three Combined Sewer Overflow
Treatment Alternatives. USEPA Report No. EPA-67Q/2-74-079, NTIS No.
PB 239 115. December 1974.
75. Springfield Sanitary District, Springfield, Illinois. Retention Basin
Control of Combined Sewer Overflows. USEPA Report No. 11023—08/70.
NTIS No. PB 200 828. August 1970.
76. Barsom, 6. Lagoon Performance and the State of Lagoon Technology.
USEPA Report No. EPA-R2-73-144. NTIS No. PB 233 129. June 1973.
77. Hickoek, E. A., etal. Urban Runoff Treatment Methods. Volume I, Non-
Structural Wetland Treatment. USEPA Demonstration Grant No. S-802535.
Final Report. Auaust 1977. At Press.
78. Metcalf & Eddy, Inc. Land Treatment of Municipal Wastewater, Tech-
nology Transfer. USEPA and U.S. Army Corps of Engineers. In Prepara-
tion.
79. Popkin, B. P. Effect of a Grass and Soil Filter on Tucson Urban Runoff:
a Preliminary Evaluation. Hydrology and Water Resources of Arizona and
the Southwest, Volume 3, 1972.
302
-------
80. Spang!er, F. L., et al. Wasttwater Treatment by Natural and Artificial
Marshes. USEPA Report No. EPA-600/2-76-207. NTIS No. PB 259 992.
September 1976.
81. Pound, C. E., et al. Costs of Wastewater Treatment by Land Application.
USEPA Report No. EPA-430/9-75-Q03. June 1975.
82. Field, R., etal. In: Proceedings of Workshop on Microorganisms in
Urban Stormwater. USEPA Report No. EPA-600/2-76-244. NTIS No. PB
263 030. November 1976.
83. Engelbrecht, R. S., et_al_. New Microbial Indicators of Wastewater
Chlorination Efficiency. USEPA Report No. EPA-670/2-73-082, NTIS
No. PB 334 169. February 1974.
84. Davis, E. M. Maximum Utilization of Water Resources in a Planned Com-
munity; Bacterial Characteristics of Stormwaters in Developing Rural
Areas. USEPA Research Grant R-802433. 1976. Draft Report.
85. Olivieri, V. P., et al. Microorganisms in Urban Stormwater. USEPA
Report No. EPA-600/2-77-087. 1977. At Press.
86. Weber, James F. Demonstration of Interim Techniques for Reclamation of
Polluted Beachwater. USEPA Report No. EPA-600/2-76-228. NTIS No. PB
258 192. 1976.
87. Lager, J. A. Trip Report; Fitchburg, Massachusetts (Dynactor);
Report on the Operation of the Stormwater Treatment Demonstration Pro-
ject; and RP Industries, Inc., Report - Automatic Storm and Domestic
Sewage Continuous Flow treatment System, March 26, 1974.
88. Pontius, U. R., etal. Hypochlorination of Polluted Stormwater Pumpage
at New Orleans. TWA Report No. EPA-670/2-73-067. NTIS No. HB
-------
93, Metcalf & Eddy, Inc. Report to National Commission on Water Quality on
Assessment of Technologies and Costs for Publicly Owned Treatment
Works Under Public Law 92-500, Volumes I, II, and III. September 1975.
SECTION 8
1, Metcalf & Eddy, Inc. Wastewater Engineering and Management Plan for
Boston Harbor-Eastern Massachusetts Metropolitan Area. Technical Data.
Volume 7, Combined Sewer Overflow Regulation. Metropolitan District
Commission. November 1975.
2. Camp, Dresser & McKee. Report on Improvements to the Boston Main
Drainage System. City of Boston. September 1967.
3. U.S. Environmental Protection Agency, and Booz, Allen and Hamilton Inc.
Draft Environmental Impact Statement, Tunnel Component of the Tunnel and
Reservoir Plan Proposed by the Metropolitan Sanitary District of
Greater Chicago; Mainstream Tunnel System, 59th Street to Addison
Street. March 1976.
4. Watt, T. R,, et a1. Sewerage System Monitoring and Remote Control.
USEPA Report No. EPA-670/2-75-020. NTIS No. PB 242 107. May 1975.
5. City of Milwaukee, Wisconsin, and Consoer, Townsend and Associates.
Detention Tank for Combined Sewer Overflow, Milwaukee, Wisconsin,
Demonstration Project. USEPA Report No. EPA-600/2-75-071, NTIS No,
PB 250 427. December 1975.
6. Mahida, V. U. and F. J. Dedecker. Multi-Purpose Combined Sewer Overflow
Treatment Facility, Mount Clemens, Michigan. USEPA Report No. EPA-670/
2-75-010. NTIS No. PB 242 914. May 1975.
7. Drehwfnq, Frank J., et al. Combined Sewer Overflow Abatement Program -
Alternative Analysis Studies. USEPA Grant No. Y-005141. November 1976.
Draft Report.
8. Drehwing, Frank J., et al. Combined Sewer Overflow Abatement Program -
Network and Water QuaTTEy Modeling Studies. USEPA Grant No. Y-005141.
November 1976. Draft Report.
9. Drehwing, Frank J., et al. Combined Sewer Overflow Abatement Program -
Pilot Plant Studies. USEPA Grant No. Y-005141. November 1976.
Draft Report.
10. Wei born, Harold L. Surge Facility for Wet and Dry Weather Flow Control.
USEPA Report No. EPA-670/2-74-075. NTIS No. PB 238 905. November 1974.
11. Metcalf & Eddy, Inc. Report to the City of Saginaw, Michigan, on Waste
Water Treatment Facilities and Intercepting System. March 8, 1967.
304
-------
12. Metcalf & Eddy, Inc. Report to the City of Saginaw, Michigan, Upon the
Recommended Plan for Abating Pollution From Combined Sewage Overflows.
March 21, 1972.
13. Metcalf & Eddy, Inc. Saginaw, Michigan, Combined Sewer Overflow Abate-
ment Plan - Preliminary Design Report (March 1973), and Hancock Street
Facility Bid Tabulation (September 1976).
14. City and County of San Francisco. Newsletter I, Wastewater Management
Public Participation Program. San Francisco Wastewater Management Pro-
gram Overview. January 1977.
15. Department of Public Works, City and County of San Francisco, Assisted
by J. B. Gilbert & Associates. Overview Facilities Plan, August 1975 -
San Francisco Master Plan Wastewater Management. August 1975.
16. Bureau of Sanitary Engineering, City and County of San Francisco, and
Water Resources Engineers, Inc. Demonstrate Real-Time Automatic Control
in Combined Sewer Systems - Progress Report Number 3. USEPA Demonstra-
tion Grant No. S-803743. April 1977.
17. Municipality of Metropolitan Seattle. Maximizing Storage in Combined
Sewer Systems. USEPA Report No. 11022ELK12/71. NTIS No. PB 209 861.
December 1971.
18. Leiser, C. P. Computer Management of a Combined Sewer System. USEPA
Report No. EPA-67Q/2-74-Q22. NTIS No. PB 235 717. July 1974.
19. Maximum Utilization of Water Resources in a Planned Community. Depart-
ment of Environmental Science and Engineering, Rice University. USEPA
Research Grant No. R-8Q2433, September 1974. Draft Report.
20. Everhart, R. C. New Town Planned Around Environmental Aspects. Civil
Engineering - ASCE. September 1973.
21, What's New in Dallas and Texas? Woodlands - New Town is Planned Around
Ecology. Civil Engineering - ASCE. March 1977.
305
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APPENDIX
Table A-l. NATIONAL RAINFALL-RUNOFF-QUALITY DATA BANK
SUMMARY OF DATA - DECEMBER 1976a
i U
Location
Bronart County,
Florida
San Francisco,
California
Racine,
Mlsccnsln
Lincoln.
fJebrassa
Windsor,
Ontario
Lancaster,
Pennsylvania
Seattle.
Washington
Baltimore,
Maryland
Chicago,
Illinois
Oianpaign-Urbana.
Illinois
Bucynis,
Ohio
Falls Churcn,
Virginia
Durban,
North Carolina
Ulnston-Salen,
North Carolina
.Jackson.
E* ISSlSSippl
Wichita,
Kins os
SJestbury,
Ken York
niltdtlmli.
Fenns/l»ania
Los Angeles,
California
Catchaent
Residential
CfKiraerclal
Transportation
Baker Street
Hariposa Street
Brotharnood May
Vlncenta Street. «
Vlncenie Street, S
Sslby Streat
Laguna Street
Site I
39 and Holdrege
63 ana Koldrege
78 and A
Labadle Road
Stevens Avenue
View Ridge 1
View Ridge 2
South Seattle
Sou tn center
Lake Mills
Highlands
Central Business District
NorUiwDOd
Gray Haven
Oakdalc
Soneyard Creek
Sexer District .No. 8
Trlpps Run
Third For*
Tar Branch
Crano Crcei<
Dry Creek
Uocdeak Drive
Mrn^anortfng
Echo Park
Srea, acre
47 5
39.0
28.4
16S
223
180
16
21
3400
375
329
79
85
35?
29 5
134
630
105
27 5
24
150
as
27. S
47.4
23.3
12 9
2250
179
332
1069
384
285
1883
14 7
5326
252
Drainage
systen
S
S
S
C
C
C
S
S
C
C
C
S
S
S
S
C
S
S
S
S
S
S
C
S
S
C
S
C
S
S
S
S
S
S
C
S
storms
Quantl £/
32b
-.a
-,»
4
4
4
1
1
8
2
9
20
15
14
22
7
30
5
31
30
7
4
5
14
29
21
2B
10
10
15
17
1?
8
10
16
18
r of
witn
Quality
35b
14^
4°
4
4
4
1
1
8
2
9
20
IS
1*
22
7
30
5
31
30
7
4
S
—
„
„
_„
„
__
__
_.
..
^_
a See discussion In Section 1
b Additional daw currently being reduced by USGS.
acres x 0 4fji • ha
306
-------
GLOSSARY
Aerated lagoon—A natural or artificial wastewater treatment lagoon (gener-
ally from 4 to 12 feet deep) in which mechanical or diffused-air aeration
is used to supplement the oxygen supply.
Biological treatment processes—Means of treatment in which bacterial or
biochemical action is intensified to stabilize, oxidize, and nitrify the
unstable organic matter present. Trickling filters, activated sludge pro-
cesses, and lagoons are examples,
BMP--Best Management Practices, Nonstructural and low structurally inten-
sive measures for controlling stormwater pollution by attacking the problem
at its source.
BCD—Biochemical Oxygen Demand. The quantity of dissolved oxygen used by
microorganisms in the biochemical oxidation of organic matter and oxidizable
inorganic matter by aerobic biological action. Generally refers to the stan-
dard 5-day BOD test.
Combined sewage.--Sewage containing both domestic sewage and surface water or
stormwater, with or without industrial wastes. Includes flow in heavily
infiltrated sanitary sewer systems as well as combined sewer systems.
Combined sewei—A sewer "receiving both intercepted surface runoff and munic-
ipal sewage.
Combined sewer overflow—Flow from a combined sewer in excess of the inter-
ceptor capacity that is discharged into a receiving water.
COD—Chemical Oxygen Demand. The quantity of oxygen required to oxidize
organic matter in the presence of a strong oxidizing agent in an acidic
medium,
CSO--Combined Sewer Overflow.
Detention--The slowing, dampening, or attenuating of flows either entering
the sewer system or within the sewer system by temporarily holding the water
on a surface area, in a storage basin, or within the sewer itself.
Pi si nf ection—The art of killing the larger portion of microorganisms in or
on a substance with the probability that all pathogenic bacteria are killed
by the agent used.
307
-------
Domestic sewage—Sewage derived principally from dwellings, business build-
ings, institutions, and the like. It may or may not contain groundwater.
DPP--A method for measuring chlorine dioxide, hypochlorite, free chlorine,
and cloramines using the DPD (N. N. Diethyl-p-phenylenediamine) indicator
solution.
Dual treatment—Those processes or facilities designed for operating on both
dry- and wet-weather flows.
Dynamic regulator—A semiautomatic or automatic regulator device which may or
may not have movable parts that are sensitive to hydraulic conditions at
their points of installation and are capable of adjusting themselves to vari-
ations in such conditions or of being adjusted by remote control to meet
hydraulic conditions at points of installation or at other points in the
total combined sewer system.
Equalization—The averaging (or method for averaging) of variations in flow
and composition of a liquid.
First flush—The condition, often occurring in storm sewer discharges and
combined sewer overflows, in which a disproportionately high pollutional load
is carried in the first portion of the discharge or overflow.
F/M—Food to Microorganism Ratio. Calculated as the rate of BOD loading in
kg (Ibs) per day divided by the kg (Ibs) of mixed liquor suspended solids
under aeration in the contact tank on]y_.
Infiltrated municipal sewage—That flow in a sanitary sewer resulting from a
combination of municipal sewage and excessive volumes of infiltration/inflow
resulting from precipitation.
Infiltration—The water entering a sewer system and service connections from
the ground, through such means as, but not limited to, defective pipes, pipe
joints, connections, or manhole walls. Infiltration does not include, and is
distinguished from, inflow.
Infiltration ratio—The ratio of rainfall volume entering the sewers to the
total rainfall volume.
Inflow—The water discharged into a sewer system and service connections
from such sources as, but not limited to, roof leaders, cellar, yard, and
area drains, foundation drains, cooling water discharges, drains from
springs and swampy areas, manhole covers, cross connections from storm
sewers and combined sewers, catch basins, stormwaters, surface runoff,
street wash waters, or drainage. Inflow does not include, and is distin-
guished from, infiltration.
In-system—•Within the physical confines of the sewer pipe network.
308
-------
Interceptedsurfacerunoff—That portion of surface runoff that enters a
sewer, either storm or combined, directly through catchbasins, inlets, etc.
Interceptor—A sewer that receives dry-weather flow from a number of trans-
verse combined sewers and additional predetermined quantities of intercepted
surface runoff and conveys such waters to a point for treatment,
interim'ttent_point_source—Any discernible, confined, and discrete conveyance
from which pollutants are or may be discharged on a noncontinuous basis.
Muni cipal sewage—Sewage from a community which may be composed of domestic
sewage, industrial wastes, or both.
Npppoi_nt so urce--Any unconfined and nondiscrete conveyance from which pollu-
tants are or may be discharged.
Nonsewered urban _runpf_f--Tnat part of the precipitation which runs off the
surface of an urban drainage area and reaches a stream or other body of
water without passing through a sewer system.
Overflow—Q) The flow discharging from a sewer resulting from combined
sewage, storm wastewater, or extraneous flows and normal flows that exceed
the sewer capacity. (2) The location at which such flows leave the sewer.
Oxidation pond--A basin (generally 2 to 6 feet deep) used for retention of
wastewaters before final disposal, in which biological oxidation of organic
matter is effected by natural or artificially accelerated transfer of oxygen
to the water from air.
Physjcal-chemical^treatment processes—• Means of treatment in which the
removal of pollutants is brought about primarily by chemical clarification
in conjunction with physical processes. The process string generally
includes preliminary treatment, chemical clarification, filtration, carbon
adsorption, and disinfection.
Physical treatment operations--Means of treatment in which the application of
physical forces predominates. Screening, sedimentation, flotations and fil-
tration are examples. Physical treatment operations may or may not include
chemical additions.
Point source--Any discernible, confined, and discrete conveyance from which
pollutants are or may be discharged.
Pollutant—Any harmful or objectionable material in or change in physical
characteristic of water or sewage.
Pretreatment—The removal of material such as gross solids, grit, grease,
and scum from sewage flows prior to physical, biological, or physical-
chemical treatment processes to improve treatability. Pretreatment may
include screening, grit removal, skimming, preaeration, and flocculation.
309
-------
Regulator—A structure which controls the amount of sewage entering an inter-
ceptor by storing in a trunk line or diverting some portion of the flow to
an outfall.
Retention—The prevention of runoff from entering the sewer system by storing
on a surface area or in a storage basin.
Sanitary sewer--A sewer that carries liquid and water-carried wastes from
residences, commercial buildings, industrial plants, and institutions,
together with relatively low quantities of ground, storm, and surface waters
that are not admitted intentionally.
SCS—Soil Conservation Service.
Sewer—A pipe or conduit generally closed, but normally not flowing full, for
carrying sewage or other waste liquids.
Sewerage—System of piping, with appurtenances, for collecting and conveying
wastewaters from source to discharge,
SB—Specific Gravity.
Static regulator—A regulator device which has no moving parts or has movable
parts which are insensitive to hydraulic conditions at the point of installa-
tion and which are not capable of adjusting themselves to meet varying flow
or level conditions in the regulator-overflow structure.
Storm flow—Overland flow, sewer flow, or receiving stream flow caused
totally or partially by surface runoff or snowmelt.
Storm sewer—A sewer that carries intercepted surface runoff, street wash and
other wash waters, or drainage, but excludes domestic sewage and industrial
wastes.
Storm sewerdischarge—Flow from a storm sewer that is discharged into a
receiving water,
Stormwater—Water resulting from precipitation which either percolates into
the soTT, runs off freely from the surface, or is captured by storm sewer,
combined sewer, and to a limited degree sanitary sewer facilities.
•Surcharge--The flow condition occurring in closed conduits when the hydraulic
grade line is above the crown of the sewer.
Surface runoff—Precipitation that falls onto the surfaces of roots, streets,
ground, etc., and is not absorbed or retained by that surface, thereby col-
lecting and running off.
Trickling filter—A filter consisting of an Artificial bed of coarse mate-
rial, such as broken stone, clinkers, slate, slats, brush, or plastic
materials, over which sewage is distributed or applied in drops, films, or
spray from troughs, drippers, moving distributors, or fixed nozzles, and
310
-------
through which it trickles to the underdrains, giving opportunity for the
formation of zoogleal slimes which clarify and oxidize the sewage.
Urban runoff—Surface runoff from an urban drainage area that reaches a
stream or other body of water or a sewer.
Was_tgwate_r—The spent water of a community. See Municipal Sewage and
Combined Sewage.
311
-------
CONVERSION FACTORS
U.S. Customary to SI (Metric)
13.5. custwnary unit
Kama
acre
a ere- foot
acre- 1 neb
cubic foot
cubic feet per Blnute
cubic feet per ralmite oer 100 gallons
cubic feet per pound
cubic feet per second
cubic feet per square foot per irtnule
cubic Inch
cubic yard
degrees Fahrenheit
feet per minute
feet per second
foot (feet)
gallon(s)
gallons per acra per day
gallons per capita per day
gsllons per day
gallons per foot per minute
gallons per tiinuts
gallons per square foot
gallons per square foot per day
gallons per square foot per minute
horsepower
Inch(es)
Inches per hoar
rails
Billion gallons
million gallons per acre
million gallons per acre per day
million gallons per day
relll (on gallons per square mile
parts per billion
parts per 311 1 lion
pound(s)
pounds cer acre per day
pounds per cubic foot
pouncs per 1000 cubic feet
pounds p«r nilc
pounds per million gallons
pound; per square toot
pounds per 1000 square feet per day
pounds per square Inch
squsra foot
square Inch
square mile
square yard
standard cubic feet p«r minute
tan (short)
tons per acre
tons per square mile
yard
/Uibreviatlon
acre
acre-fc
acre- in.
ft3
ftVnln
ft3/mn 100 gal
fi3/ib
ft3/s
ft3/ft2 rein
In.J
yd 3
*T
ft/Bin
ft/*
ft
gal
gM/acTB'*!
gal/capita d
gal/d
gal /ft nin
gal/Bin
gal/ft2
gil/ft2 d
sal/ftZ-nlri
hp
In
1n,/h
mi
Ngal/acre
Hgal/Kre d
Hgal/d
Kgal/irt2
ppb
ppn
Ib
Ib/acre-d
tb/TlJ
lb/1000 ft3
lb/
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reitne be/ore camplctiiiff
1 REPORT NO.
EPA-600/8-77-OH
3 RECIPIENT'S AGCESSIOWNQ,
4. TITLE AND SUBTITLE
URBAN STORMWATER MANAGEMENT AND TECHNOLOGY:
UPDATE AND USERS' GUIDE
5 REPORT DATE
'September 1977 (Issuing Date)
6 PERFORMING ORGANIZATION CODE
7 AUTHORSJohn A< Lager, William G. Smith, William G.
Lynardj Robert M. Finns and E. John Finnemore
8. PERFORMING ORGANIZATION REPORT NO
9, PERFORMING ORGANIZATION NAME AND AOOHESS
Metcalf & Eddy, Inc.
1029 Corporation Way
P.O. Box 10-046
Palo Alto, California 94303
10 PROGRAM ELEMENT NO,
1BC6H
11. CONTRACT
68-03-2228
NO
12, SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory--Cin.,QH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final Report
14 SPONSORING AGENCY CODE
EPA/600/14
IB. SUPPLEMENTARY NOTES
Supplement to EPA-670/2-74-040, "Urban Stormwater Management and
Technology, An Assessment." Project Officer; Richard Field, Chief, Storm and
Combined Sewer Section. (201) 321-6674, 8-340-6674
16. ABSTRACT
ft continuation and reexamlnatJon of the state-of-the-art of storm and combined sewer overflow technology is presented.
Essential areas of progress of the stornwtter research and development program are keyed to the approach methodology and
user assistance tools available, stormwater characterization, and evaluation of control measures. Results of the
program are visible through current and ongoing master planning efforts. Assessment of urban runoff pollution 1s
referenced to the developing national data base, localized through selective monitoring and analysis, and quantified as
to potential source and magnitude using techniques ranging from simplified desktop procedures to complex simulation
models. Stontwater pollutants are characterized by (1) source potential, (2) discharge characteristics, (3! residual
products, and 14) receiving water Inpacts. Control and corrective measures are separated Into nonstruetural, termed
Best Management Practices (BHPs), and structural alternatives. Best Management Practices focus on source abatement,
whereas structural alternates roughly parallel conventional wastewater treatment practices of end-ot-the-pipe
correction. Structural alternatives may Include storage (volune sensitive) and treatment (rate sensitive) options and
balances. Hultlpurpose and Integrated Idry-ttet) facilities have been the most successful vrith process simplicity and
operational control flexibility prime considerations. Best Management Practices have decided benefits over structural
alternatives--Including lowr cost, earlier results, and an improved and cleaner neighborhood ewiroraient—-but lack
quantified action-Impact relationships. For combined sewer overflow abatement, increasing degrees of structural control
1s necessary. Successful program Implementation is Illustrated for several selected case histories.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Disinfection, Drainage, *Water pollution, *Waste treat-
ment, *Surface water runoff, *Runoff, *Wastewater,
*Sewage, Contaminants, *Water quality, Cost analysis,
*Cost effectiveness, *Storage tanks, *Storm sewers,
*0verflows--sewers, *Combined sewers, Hydrology,
Hydraulics, *Mathernatica1 models, Remote control
b, IDENTIFIERS/OPEN ENDED TERMS
Drainage systems. Water pollution
control, Biological treatment,
Pollution abatement, *Storm run-
off, *Water pollution sources.
Water pollution effects, Source
control, *Urban hydrology,
*Con\bined sewer overflows.
Physical processes
18, DISTRIBUTION STATEMENT
Release to Public
19 SECURITY CLASS (ThtsReparl)
Unclassified
21, NO OF PAGES
331
20 SECURITY CLASS (This page I
Unclassified
22 PRICE
EPA Form 2220-1 (9-73)
313
5. GOTOKHENT PRIHTIHG OFFICE 1977-757" 1W6582 Region Ho. 5-11
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TECHNICAL REPORT DATA
(Please read Instructions on the m erSf beicre compk ting}
1 HEPOST NO,
EPA-600/8-77-014
3 RECIPIENT'S ACCESS]Of*NO.
i, TITLE AND SUBTITLE
URBAN STORMWATER MANAGEMENT AND TECHNOLOGY;
UPDATE AND USERS' 6UIDE
5, REPORT DATi
September 1977 (I s s u1ng Date)
6 PERFORMING ORGANIZATION CODE
7 AUTHORCS) John ft_ Lager, Will 1 am G. Smith, William G.
Lynard, Robert M. Finn, and E. John Finnemore
8. PERFORMING ORGANIZATION REPORT NO
i. PERFORMING ORGANIZATION NAME AND ADDRESS
Metcalf & Eddy, Inc.
1029 Corporation Way
P.O. Box 10-046
Palo Alto, California 94303
10 PROGRAM ELEMENT NO.
1BC611
11. CONTRACT
68-03-2228
NO
12 SPONSOBING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory—Cin.,OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13 TYPE OF REPORT AND PERIOD COVERED
Final Reoort
14 SPONSORING AGENCY CODE
EPA/600/H
is SUPPLEMENTARY NOTES; Supplement to EPA-670/2-74-040, "Urban Stormwater Management and
Technology, An Assessment." Project Officer: Richard Field, Chief, Storm and
Combined Sewer Section, (201) 321-6674, 8-340-6674
16 ABSTRACT
A continuation ind reexanlnation of the state-of-the-art of storm and couwlned sewer overflow technology Is presented.
Essential areas of progress of the storawater research and development program ere keyed to the approach methodology and
user assistance tools available, storawater characterization, and evaluation of control measures. Results of tne
program are visible through current and ongoing master planning efforts. Assessment of urban runoff pollution is
referenced to the developing national data base, localized through selective monitoring and anil/sis, and quantified as
to potential source and aagmtude using techniques ranging frora simplified desktop procedures to complex simulation
models. Stormwater pollutants are characterized by (1) source potential, (2) discharge characteristics, (3) residual
products, and (4) receiving water Impacts. Control and corrective measures are separated into nonstructural, termed
Best Management Practices (BMPs), and structural alternatives. Best Management Practices focus on source abatement,
whereas structural alternates roughly parallel conventional xastewater treatment practices of end-of-the-pipe
correction. Structural alternatives may Include storage (volume sensitive) and treatment {rate sensitive! options and
balances. Multipurpose and integrated (dry-wet! facilities have been the most successful with process simplicity and
operational control flexibility prloe considerations. Best Management Practices have decided benefits over structural
alternat1ves--fncluding lower cost, earlier results, and an improved and cleaner neighborhood environment—but lack
quantified action-Impact relationships. For combined sewer overflow abatement, increasing degrees of structural control
is necessary. Successful progran implementation is Illustrated for several selected case histories.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.JDENTIFlERS/OPEN ENDED TERMS
c cos AT i Field/Group
Disinfection, Drainage, *4ater pollution, *Waste treat-
merit, *Surface water runoff, *Runoff, *Wastewater,
*Sewage, Contaminants, *Water quality, Cost analysis,
*Cost effectiveness, *Storage tanks, *Starm sewers,
*0verflows—sewers, *Combined sewers, Hydrology,
Hydraulics, *Hatheraatical models. Remote control
Drainage systems, Water
control, Biological treatment,
Pollution abatement, *Storm run-
off, *Water pollution sources,
Mater pollution effects, Source
control, *Urban hydrology,
*Coinbined sewer overflows,
Physical processes
13B
13. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (Tills Report)
Unclassified
21. NO OP PAGES
331
20 SECURITY CLASS (Tliispage)
Unclassified
22. PRICE
EPA Form 2220-1 (8-73)
313
-ft-U S GOVidSBENT HINTIHG OFFICE 1977-757-1"(0/6582 Region Ho. 5-11
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