EPA-R2-73-242
MAY 1973
f\
invironmental Protection Technology Series
Temporary Detention of
Storm and Combined Sewage
in Natural Underground Formations
Office of Research and Monitoring
U.S. Environmental Protection Agency
Washington, D.C. 20460
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five broad
categories were established to facilitate further
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL
PROTECTION TECHNOLOGY series. This series
describes research performed to develop and
demonstrate instrumentation, equipment and
methodology to repair or prevent environmental
degradation from point and non-point sources of
pollution. This work provides the new or improved
technology required for the control and treatment
of pollution sources to meet environmental quality
standards.
-------
EPA-R2-73-242
May 1973
TEMPORARY DETENTION OF STORM AND COMBINED SEWAGE
IN NATURAL UNDERGROUND FORMATIONS
By
City of St. Paul, Minnesota
Project 11030 DSL
Program Element 1B2034
Project Officer
Clarence C. Oster
Minnesota-Wisconsin District Office
U.S. Environmental Protection Agency
7401 Lyndale Avenue South
Minneapolis, Minnesota 55423
Prepared for
OFFICE OF RESEARCH AND MONITORING
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C, 20402
Price 95 cents domestic postpaid or 70 cents OPO Bookstore
-------
EPA Review Notice
This report has been reviewed by the Environmental
Protection Agency and approved for publication.
Approval does not signify that the contents
necessarily reflect the views and policies of the
Environmental Protection Agency, nor does mention
of the trade names or commercial products constitute
endorsement or recommendations for use.
-------
ABSTRACT
The object of this study was to demonstrate the feasibility of
temporarily detaining storm and combined sewage in natural under-
ground formations and was to proceed in three phases.
Five sites were selected for subsurface geological and geophysical
investigation for the purpose of determining which site possessed
subsurface conditions most suitable for storing and retrieving
storm and combined sewage.
The geophysical work required six resistivity soundings as well
as resistivity survey involving five traverses. Based on this
work, three sites were selected for test boring. A four-inch (4")
test boring was made at each of these three sites. Two of the
sites were too shallow for later demonstration of the technique.
The third site was selected for the test pumping of Phase I.
Because of the small underground storage available, the City of
South St. Paul elected not to continue into Phases II and III.
Included in the scope of work for Phase I was an investigation,
analysis, and discussion of methods of solids separation which
might be used for storm and combined sewage in Phase II and III,
prior to injection of the effluent underground.
Alternate proposals, including surface detention and treatment,
and total separation of storm and sanitary sewers, were also
considered.
This report was submitted in fulfillment of Project No. 11030 DSL,
under the partial sponsorship of the Environmental Protection Agency.
iii
-------
CONTENTS
Section
I
II
III
IV
V
VI
VII
VIII
IX
X
Conclusions
Recommendations
Introduction
Field Investigation and Testing
Suitability of Test Site
Solids Separation Investigation
Discussion of Results
Acknowledgement s
Glossary of Pertinent Terms
Appendices
Page
1
3
5
9
41
45
49
51
53
55
-------
NO.
1 LOCATION MAP 10
2 STANLEY AVENUE SITE 1]-
3 CENTRAL AVENUE SITE 12
4 WEnSTTWORTH AVENUE SITE 13
5 INTERSTATE 494 SITE 14
6 TREATMENT PLANT SITE 15
7 ELECTRICAL RESISTIVITY SOUNDING NO. 1 CENTRAL AVENUE SITE 17
8 ELECTRICAL RESISTIVITY SOUNDING NO. 2 STANLEY AVENUE SITE 18
9 ELECTRICAL RESISTIVITY SOUNDING NO. 3 1-494 SITE 19
10 ELECTRICAL RESISTIVITY SOUNDING NO. 4 1-494 SITE 20
11 ELECTRICAL RESISTIVITY SOUNDING NO. 5 WENTKDRTH AVENUE SITE 21
12 ELECTRICAL RESISTIVITY SOUNDING NO. 6 TREATMENT PLANT SITE 22
13 FOUNDATION BORINGS WEST END 1-494 BRIDGE NO. 5993 23
14 FINAL PUMP TEST SITE 24
15 WELL LOGS TEST WELL NO. 1 25
16 WELL LOGS OBSERVATION WELL 1 26
17 WELL LOGS OBSERVATION WELL 2 27
18 ELECTRIC LOGS TEST HOLES 1 & 2 28
19 PUMP TEST DISTANCE DRAWDOWN 37
20 PUMP TEST WATER LEVELS 38
21 RECHARGE OPERATING CONDITIONS 1000 GPM 43
22 THEORETICAL WELL CONSTRUCTION DIAGRAM 44
23 SCHEME A (TYPICAL SEWAGE TREATMENT FACILITIES) 61
24 SCHEME B (TYPICAL SEWAGE TREATMENT FACILITIES) 63
25 SCHEME C (TYPICAL SEWAGE TREATMENT FACILITIES) 66
26 COMBINED SEWAGE DISCHARGE SEWAGE TREATMENT PLANT 67
vi
-------
TABLES
No. Page
I Water Analysis Test Hole No. 1 Pump Test 30
II Pump Test Measurements Test Well No. 1 31
III Pump Test Measurements Observation Well No. 1 33
IV Pump Test Measurements Observation Well No. 2 35
V Projected Operating Conditions Five Wells 42
VI Frequency of Runoff 69
VII Disinfection 70
V1L
-------
SECTION I
CONCLUSIONS
The storage of storm or combined sewage in underground formations
requires geologic formations that possess sufficient physical capacity
to permit injection of the sewage at a rate that will sufficiently
match the incoming flow rate. Optimization of injection and inflow
rates is imperative, if the need to provide large surface detention
basins is to be avoided - particularly in urban areas.
Based on tests taken at five selected sites along the City river-
front, the most suitable location permitted a maximum injection rate
of 1000 GPM, or 1,400,000 gallons-per-day.
A rainfall equivalent to the test areas' five-year-storm frequency
would result in some 70-million gallons of runoff, or a peak rate of
over 2,500,000 GPM. Thus, the obvious necessity of providing storage
basins to minimize the number and size of injection systems.
In addition, the studies point to a need to remove all solids larger
than 5-microns. To accomplish this, sedimentation basins, chemical
flocculation, and the use of sand filters or fine screens would be
required.
The potential for contamination of underground water supply sources
must also be carefully evaluated where such methods are considered.
It was determined that aforementioned facility requirements were not
economically feasible in view of other methods available. In view
of the need for sedimentation, flocculation, and filters or screens -
it appears that, with few additions, the effluent could be discharged
directly to the river.
Because of the findings, it was decided not to proceed with Phases II
and III, the objectives of which are described in the introduction.
-------
SECTION II
RECOMMENDATIONS
In order to demonstrate feasibility of the underground detention
method of storm water, it is recommended that the Office of
Research and Monitoring consider a new demonstration grant where
a suitable underground formation with sufficient surface ponding
area for solids separation and sufficient underground input
capacity is available.
-------
SECTION III
INTRODUCTION
The City of South St. Paul, Minnesota is a part of the seven county
metropolitan area of the Twin Cities. It is located on the right bank
of the Mississippi River adjacent to the southerly portion of St. Paul.
It is bounded on the west by West St. Paul and on the south by Inver
Grove Heights.
The City has a population of about 24,000 but due to the presence of
large livestock and meat packing industries, the population equivalent
for sewage treatment purposes was approximately 800,000 at the time of
study, now decreased to 400,000 because of the closing down of a major
meat packing industry. The sewage disposal plant at the time of the
study was owned by the City but is presently owned by the Metropolitan
Sewer Board and is in the process of being phased out and will act as
a pretreatment facility for the packing industry waste. All domestic
waste water and pretreated packing waste water will be pumped to the
Pigs Eye Island treatment plant by a 48" force main.
The City is situated principally along the Mississippi River at the
foot of and parallel to a line of bluffs which rise sharply from the
valley on the west side of the river. During periods of high intensity
rainfall, storm water runoff is high and is conveyed to the City
system of combined storm and sanitary sewers. The Sewage Disposal
Plant is bypassed during these periods and storm and sanitary sewage
is discharged into the Mississippi River without treatment.
A study of the combined sewer problem in South St. Paul was under-
taken and completed and data regarding the study has been provided
in the Appendix of this report. As of one of the possible solutions
to this problem and in order to demonstrate and report on the
feasibility thereof, the City Council accepted, on July 22, 1968, an
offer of a Federal Grant by the Federal Water Pollution Control Admin-
istration, predecessors to the EPA and hereafter referred in this
report as EPA, for a demonstration project with temporary detention
of storm and combined sewage in natural underground formations. The
project was originally designated as Demonstration Project No.
WPRD249-01 and was subsequently changed to Project No. 11030DSL.
Under an agreement of 9 September, 1968, the City of South St. Paul
engaged MacKichan and Madsen to undertake the work. At the request
of the EPA, the project was divided into three phases. Phase I
consisted of selecting a site with a suitable natural underground
formation into which storm water could be injected during Phase II
and combined storm and sanitary sewage during Phase III. This report
is concerned with the results of investigation and analysis on Phase I
only of the project.
-------
The objective of Phase I, II, and III of the Demonstration Project
was to demonstrate and report on the feasibility of using natural,
permeable underground formations in South St. Paul for temporary
detention of both storm water and combined sewage during periods
of peak runoff when the wastes must be diverted into the Mississippi
River without treatment. This method could have possible national
applications in areas with similar conditions. It was considered
as one method of solving the combined sewer problem in the City of
South St. Paul and to assist in the abatement of pollution in the
Mississippi River.
This report is limited to a discussion of the results of the basic
investigation called for in Phase I; however, the scope of work for
all three phases is described hereafter.
Phase I has consisted of basic investigations to include geophysical,
geological, and hydrological analysis of underground formations in
South St. Paul, in order to select a site into which, in later phases,
clear water, storm water, and combined sewage could be pumped, monitored
and recovered for demonstration of the technique of temporary detention
in permeable underground formations. Sufficient geophysical surveys,
test drilling, and test pumping were undertaken to search for permeable
formations suitable for developing the technique and subsequent phases.
Phase I also included an investigation analysis and recommendations for
a method of solid separation of storm and combined sewage to be tested
in Phases II and III.
Phase II was to consist of demonstration of the system at the location
selected in Phase I, in order to evaluate the technique under varied
inflow conditions. In this phase, City water was to be introduced
into the permeable formations by a combination of infiltration basins
and gravity or purger wells within the retention pool. Direction and
rate of water movement would be established by quantitative pumping
test procedures. These procedures are established methods of
evaluating movement of liquids in permeable formations. Observation
piezometer wells would be used to monitor the changes in water quality
as the liquid introduced underground moves through the formation.
After testing with City water and after separation of solids by methods
recommended in Phase I, storm water was to be introduced into the
underground system. The storm water would be monitored, analyzed and
finally recovered by pumping.
Phase III was to consist of demonstrating the feasibility for temporary
underground storage of combinations of storm water and sanitary sewage.
The problem of economically separating the solids from the combined
waters would be further investigated and evaluated. The remaining
effluent would then be diverted into the underground system, monitored
and recovered. A final report was to be prepared which would present
the results of the investigation, testing and evaluation undertaken in
all three phases, along with recommendations for further application of
the technique in South St. Paul and nationally.
-------
It should be emphasized at this point that the basic purpose of Phase I
was to locate a site in South St. Paul with an underground formation
considered to be geologically and hydrologically suitable for actual
demonstration of the technique and subsequent phases. The applicability
of the temporary detention method in the City of South St. Paul and other
parts of the nation could only be determined after demonstration of
feasibility for storm water in Phase II and for combined sewage in Phase III.
Phase I of the project was carried out under the general direction of
the EPA and under the direct supervision of the City of South St. Paul by
their former City Engineer, Donald R. Peterson.
In execution of the work, the consultants, MacKichan and Madsen, retained
the services of Eugene A. Hickok and Associates, consulting hydrologists
of Wayzata, Minnesota, on the geophysical, geologic, and hydrologic
aspects of the work. A contractor was also engaged to undertake test
borings and drilling of the test well and observation wells.
To investigate, analyze, and make recommendations for methods to separate
the solids from both storm and sanitary sewage, as was called for in
Phases I and II, the services of Henningson, Durham & Richardson, Inc.
Engineers, Architects, and Planners, Omaha, Nebraska, were retained to
report on this matter. The findings of Eugene A. Hickok & Associates,
and Henningson, Durham & Richardson have been presented in the context
of this report.
-------
SECTION IV
FIELD INVESTIGATIONS AND TESTS
In order to assess the potential locations for underground storage in
South St. Paul, the initial step involved a study of maps and geologic
literature, along with consultation with the City Engineer and Super-
intendent of Sewage Disposal Plant at South St. Paul. This was
followed by field investigations, using electrical resistivity methods
to determine bedrock depths.
Based on geologic and geophysical indications, the most favorable
sites were tested by drilling, Plate 1 is a location map showing all
five sites. Plates 2 through 6 are detailed maps showing the actual
location of the electricl resistivity soundings and the test holes.
Preliminary planning limited the general field investigation to the
strip of land between Concord Street and the Mississippi River. This
area combines potential storage with the use of gravity flow and
relatively uninhabited surroundings. The geophysical method chosen
as being the most advantageous for the area was electrical resistivity.
Geological reconnaissance indicate that, within this area, the bedrock
consists of St. Peter Sandstone which is terraced in most places by
stream action. Most of this terraced area within the existing valley
was subsequently buried by more recent glacial and alluvial materials.
The target of all efforts was to locate permeable lenses within these
recent sediments, preferably underlain by impervious beds and with
enough surface area to allow for possible site development.
Electrical resistivity soundings were conducted at five sites in an
attempt to determine the thickness of recent sediments overlying
bedrock.
The basic operation in this geophysical method is the measurement of
natural electrical resistivity in the ground. The various earth materials
have differing degrees of resistance to an induced electric current,
depending on the presence and nature of contained moisture. The moisture
in a clay formation moves extremely slow, and the formation has a high
content of salts dissolved from the clay, making it a good electrolyte
and thus reducing its electrical resistivity. Sand and gravel permit
relatively rapid movement of any contained water, and they form natural
filters, which results in fresh water, with attendant high resistivity.
Dry sand and gravel would have a high resistivity, and bedrock usually
shows a definite high reading.
-------
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MocKICHAN B MAOSEN
EnglnMri
SOUTH ST. PAUL. MINNESOTA
E.A. HICKOK A ASSOCIATES
Contulting Hydrologillt
LOCATION MAP
SOUTH ST. PAUL
WENTWORTH AVE. SITE
Figure 1.
10
-------
N
0 100 200 300 FEET
E.R. SOUNDING NO. 2
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MacKICHANSMADSEN
Consulting Engineer*
SOUTH ST. PAUL,MINNESOTA
68S4 2
170-7
3-69
PLATE 2
E.A. HICKOK 8 ASSOCIATES
Consulting Hydrotogithi
STANLEY AVENUE SITE
Figure 2.
11
-------
IOO 2OO 3OO FEET
TEST HOLE NO.1
R. SOUNDING WO1
O
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MocKlCHANaMADSEN
Consulting Engine*
SOUTH ST. FftUL,MINNESOTA
EA. HICKOK ft ASSOCIATES
Consulting HydrotogUM
CENTRAL AVENUE SITE
Figure 3.
12
-------
O IOO 2OO 3OO FEET
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. WUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT ^ROJECT NO.11030 DSL
MocKICHAN a MADSEN
Con*ulting EnginMTi
SOUTH ST. PAUL, MINNESOTA
68S4.4
170-7
3-69
PLATE 4
E.A. HICKOK a ASSOCIATES
Coraulting Hydrologittt
WENTWORTH AVENUE SITE
Figure 4.
13
-------
TREATMENT PLANT ROAD /
OMB I NAT I ON
WE'R"
N
450 FEET
ELECTRICAL RESIS-
'IVITY SOUNDING
TEST HOLE
RESISTIVITY CONTOUR
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJ ECT NO. 11030 DSL
MocKICHANSMADSEN
Consulting EnginMn
SOUTH ST. PAUL.MINNESOTA
68S4.5
170-7
3-69
PLATE 5
E.A. HICKOK 8 ASSOCIATES
ConwJting Hydraogwhi
INTERSTATE 494 SITE
Figure 5.
-------
E.R. SOUNDING NO. 6
UNDERGROUND DEMONSTRATfON PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WTER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MacKICHANSMADSEN
Consulting Engine*
SOUTH ST. PAUL,MINNESOTA
68S4.6
N
IOO
200
3OO FEET
ITO-7
3-69
PLATE 6
E.A. HICKOK 8 ASSOCIATES
Consulting Hydrologisti
TREATMENT PLANT SITE
Figure 6.
15
-------
In making an electrical resistivity sounding, electrode configurations
are adjusted to read successively deeper measurements. The results of
these soundings are plotted on graphs- shown in Plates 7 thru 12. At
the Interstate 494 site, a lateral electrical resistivity survey was
made, in which several traverses were run, taking continuous measurements.
The results of this survey are shown on Plate 5 in the form of apparent
resistivity contours.
With completion of the geologic and geophysical investigation, results
were analyzed and sites chosen for test drilling. It is usually de-
sirable to correlate electrical resistivity data with known local sub-
surface conditions, such as drill hole information, as means of in-
creasing the accuracy of interpretation. In this case, there was no
opportunity to do so and, in effect, the first test hole has to provide
this information.
The first hole, TH-1, at the Central Avenue site, found limestone
bedrock at a depth of 30 feet. The electrical resistivity sounding
of this location indicated a bedrock depth range of 25 to 40 feet. The
site was considered unsuitable because of a direct hydraulic connection
between the limestone bedrock and the overlying alluvium that would
allow contamination of the underlying aquifers.
The second hole, TH-2, was located at the Interstate 494 site. For
space and drill access, the hole was located near the west property
line. The electrical resistivity sounding at this site, ER3, ER4, and
ER6, showed an increase in bedrock depth from west to east. At the
west line the sounding data was somewhat ambiguous, indicating possible
bedrock depths of 20 feet and 55 feet. Sounding ER-S3 showed a more
definite depth indication of about 50 feet. Drill hole TH-2 encountered
limestone bedrock at 30 feet. This location was considered unsuitable
for the same reason as the Central Avenue site.
Test holes were not taken at the Stanley Avenue and Wentworth sites.
Poor accessibility and limited working space was one reason for not
putting down a test hole. The electrical resistivity soundings at
both sites indicated bedrock formations at depths of 25 to 40 feet,
thus making it unsuitable for the same reason as the Central Avenue site.
Minnesota Highway Department borings at the west end of the Interstate
494 Bridge, as seen on Plate 13, show that alluvial deposits thicken to
100 feet going east from TH-2 to the bridge abutment. On the basis of
this information, another test site was chosen East of TH-2 and north
of the Interstate 494 Bridge. The final location was determined by
the need of 150 lineal feet that avoided roads, railroad track, low
ground and power line construction. The first hole at this site, TH-3,
was drilled to a 125 foot depth, all in alluvium. Two more holes,
TH-4 and TH-5, were drilled, each to a 125 foot total depth. All of
these holes were subsequently re-numbered. The southermost, an 8-inch
diameter hole to be test-pumped, was designated Test Well No. 1, TW-1.
16
-------
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MacKICHAN 8MADSEN
Consulting Engineers
SOUTH ST. PAUL,MINNESOTA
E.A. HICKOK 8 ASSOCIATES
Consulting Hydrologisfs
ELECTRICAL RESISTIVITY SOUNDING NO
CENTRAL AVENUE SITE
Figure 7.
-------
CO
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MocKICHANa MADSEN
Consulting Engineers
SOUTH ST. PAUL,MINNESOTA
E.A. HICKOK a ASSOCIATES
Consulting Hydrologies
ELECTRICAL RESISTIVITY SOUNDING NO.S
STANLEY AVENUE SITE
5 67891
Figure 8.
-------
89
6
7
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. RWJL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MocKICHAN a MADSEN
Consulting Engineers
SOUTH ST. PAUL .MINNESOTA
68S4.9
170-7
*_
3
PLATE 9
E.A. HICKOK a ASSOCIATES
Consulting Hydrdogists
ELECTRICAL RESISTIVITY SOUNDING NO. 3
1-494 SITE
67
91
5 91
Figure 9.
-------
O
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MocKICHANS MADSEN
Consulting Engineer*
SOUTH ST. PAUL, MINNESOTA
E.A. HICKOK a ASSOCIATES
Consulting Hydr-ologiitt
ELECTRICAL RESISTIVITY SOUNDING NO. 4
(NNE-SSW)
1-494 SITE
Figure 10.
-------
UNDERGROUND OEMONSTBATION PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MocKICHANSMADSEN
CantulTint Engintvn
SOUTH ST. PAUL, MINNESOTA
E.A. HICKOK 8 ASSOCIATES
Conwltma
ELECTRICAL RESBTIVITY SOUNDING NO. 5
WENTWQRTH AVENUE SITE
Figure 11.
-------
NJ
UNDERGROUND DEMONSTRATION PROJECT
CITY OFSOUTH ST.PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT MO. 11030 DSL
MocKICHAN a MADSEN
Consulting Engineer*
SOUTH ST. PAUL,MINNESOTA
E.A. HICKOK a ASSOCIATES
Consulting Hydrologistt
ELEaRICAL RESISTIVITY SOUNDING NO. 6
TREATMENT PLANT SITE
Figure 12.
-------
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MocKICHANSMADSEN
Consulting Engineers
SOUTH ST. PAUL,MINNESOTA
WEST
E.A. HICKOK 8 ASSOCIATES
Consulting Hydrologlsts
FOUNDATION BORINGS
WEST END OF 1-494
BRIDGE NO. 5993
B4
Fine Sandy
Loam
fint Sandy S,//y -
EAST
M5L
MISSiSSIPPi R. D*TU7Mo
WATER. LEVEL
__C/ay Loam
Coarse SaHat
Sea ma
Very flfte Sandy Loam
'
Gxrfs^^. M»d. Coat-tiff SanJ
Sasrct ^&/
-------
N
0 IOO 2OO 3OO FEET
OBSERVATION WELL NO.
OBSERVATION WELL NO.
TEST WELL NO- I
TREATMENT PLANT ROAD
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MacKICHANSMADSEN
Consulting Engineers
SOUTH ST. RftUL, MINNESOTA
68S4.I3
170
3-69
PLATE 14
E.A. HICKOK a ASSOCIATES
Consulting Hydrologists
FINAL PUMP TEST SITE
Figure 14.
24
-------
ELECTRIC-
....
i
~F
'C
tt
f I
i j i
-
TI
"c
r-w
Ol
1
t~*
*»
5
hfi
.C
T-
~A1
r^-
;r|
^
rx-'
H
^
F=
1
1
~~C^
M
1-5
S
K
IV
j-^
I j
X
- f
(-
£
r
i
1
"\
-\
~Y
j^
^T!
<;
ii
f
1
V.
7
/n
? ;
) f
/
/
/ !
1
,
|
'
25
GEOLOGIC LOG
Light gray - brown
s 1 ty fine sand
L ght gray - brown sand
and gravel with thin
clay seams
L ght gray silty sand
and gravel
L ight gray silt and
fine sand
L ght gray silty fine to
coarse sand with silty
clay seam at 70'
L ght gray silty fine sand
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
Mac KICHAN a MADSEN
Consulting Enginterc
SOUTH ST. PAUL, MINNESOTA
68S4 14 E.A. HICKOK 8 ASSOCIATES
171-7
3-69 WELL U)GS
TF9T WFI 1 MH II
PLATE 15
Figure 15.
25
-------
ELECTRIC
-
3*
L
}f
F
SEtf PCJ
.
h=-
-U
-M
"^1
..
:
*~~\-/
~s-
$
<
i
r"
\.
v
.x
>
f
yt
^
>._ .
X
-^
^
^
~ n~r~
' r !
] i
p
w
TEJs
OJ
)
1
f
L^
ON
T.JA
M-
i
=t^
.^r-
i 1
f,mf
^*~
'
S
i_.
r> .
,*
1 i
>^~
>
B^
^
+
1
t
1 T
~
t
'
i
1
^
i
1 1
WE
0
10
20
30
40
. so
60
70
80
90
100
110
122.5
BOTTOM
LOG
'
-
-
-
^Nf
-RF
ShV
tu
1
=}=-£>
j
'
i
-
n ^
i
!
1
1
T
t
1-
-
v
'l
[
i
- 1
rivFT-v r-
30
j
1
~^~
1
fp
n
A
1
1
i
1
1
1 i
-
1 "
H
i '
\
\
/
/
f
\
-------
ELECTRIC LOG
GEOLOGIC LOG
L ght gray - brown s i 1 ty
sand and fine gravel
L ght gray clay wi th
gravel seams
Light gray s i 1 ty sand and
gravel with thin clay
seams
27
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MocKICHANaMADSEN
Consulting Engineers
SOUTH ST PAUL, MINNESOTA
68S4.I6
171-7'
3_6g
PLATE 17
E.A. HICKOK a ASSOCIATES
Consulting Hydrologists
WELL LOGS OBSERVATION WELL NO. 2
Figure 17.
27
-------
SEjLF^-pOT ? NT | At
205
m
HOLE
10
20
31
iREsisnviTYr
£
30TTOM
28
UNDERGROUND DEMONSTRATION PROJE6T
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MocKICHANaMADSEN
Coraultfng Englnttr*
SOUTH ST. PAUL,MINNESOTA
68S4.I7
171-7
3-69
PLATE 18
E.A. HICKOK 8 ASSOCIATES
Consulting Hydrologlsts
ELECTRIC LOGS TEST HOLES I 8 2
Figure 18.
28
-------
The hole 50 feet north of TW-1 was designated Observation Well No. 1,
OW-1 and the hole 150 feet north of TW-1 was numbered Observation
Well No. 2, OW-2. Both observation wells were 4 inches in diameter.
This layout is shown on Plate 14.
All three wells were electric-logged with a Widco Portalogger, as were
TH-1 and TH-2. These logs, shown in Plates 15, 16, 17, and 18, record
self-potential and resistivity, which with data from the driller's log,
gives an accurate picture of subsurface materials and depths.
This subsurface information was used to position 10 foot long well-
screens in each well in order to take advantage of the most permeable
interval encountered in each hole. It is important in this procedure
that each wellscreen intercept essentially the same aquifer. The
electric logs indicated a good correlation between the intervals of
maximum permeability, namely the best aquifer in the three wells.
After placement of the well screen and casing to each well, the hole
was flushed of all drilling mud and developed for about four hours.
When all three wells, TW-1, OW-1, and OW-2, had been developed, pre-
parations were made to pump TW-1 at close to maximum yield while
observing water level fluctuations in all three wells. To assess the
feasibility of underground storage of fluids, it is necessary to deter-
mine the rate at which a given aquifer will accept a charge and yield
a discharge. Both events are functions of the same hydraulic properties
that define the basic capacity of the aquifer. These are the coefficients
of transmissibility and of storage. The first is defined as the quantity
of water in gallons per day, GPD, that is transmitted, under a hydraulic
gradient of one, through a vertical strip of aquifer one foot wide and
extending the full thickness of the aquifer. The coefficient of storage
is defined as the volume of water that an aquifer releases, or takes up,
per unit surface area of aquifer per unit change in the component of
head normal to the surface.
Field pumping tests, to determine the rate of decline or ground water
levels during pumping, provide the most reliable means of determining
these coefficients.
A test was conducted wherein TW-1 was pumped at a rate of 150 GPM for
24 hours while measuring water levels in TW-1 and both observation wells.
The water analysis of Test Hole No. 1 pump test is shown in Table I.
The pump test measurements are listed in Tables II, III, and IV, and
plotted on graphs as Plates 19 and 20.
29
-------
TABLE 1
WATER ANALYSIS
TEST HOLE NO. 1 PUMP TEST
El apsed
Time (Mi n . )
Sampl e No .
30 240
1 2
360 480 600 720 840 960 1080 1200 1320 1442
3 4 5 6 7 8 9 10 11 12
Analysi s
A 1 k a 1 i n i ty
Chi ori des
Calcium Hardness
Total Hardness
I ron
395
10.0
340
230
4.30
380
10.0 10.0 12.5 10.0 10.0 12.5 10.0 10.0 10.0 10.0
340
230
4.49
Sulfates
Manganese 0.60 0.63
Nitrite 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Total Nitrate 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01
Spec. Conductance 650 600 520 590 600 540 530 500 590 510 550 600
Copper 0.00
Coli form Bac. Pos. Neg.
Samples collected December 17, 1968
Analyzed December 19, 1968
-------
TABLE II
PUMP TEST MEASUREMENTS
TEST WELL NO. 1 - PUMPING WELL
DECEMBER 6, 1968
STATIC WATER LEVEL - 15.93' BELOW GRADE - PUMP RATE - 150 GPM
TIME
10:35
10:37
10:39
10:43
10:45
10:47
10:49
10:51
10:53
10:55
10:57
10:59
11 :01
11 :03
11 :05
11:10
11:15
11 :20
11 :25
11 :30
11 :35
11 :50
12:05
12:20
12:35
1 :05
1 :35
2:05
2:35
3:05
3:35
4:05
4:35
5:05
5:35
6:05
6:35
7:05
7:35
8:05
ELAPSED
TIME - MINUTES
0
2
4
8
10
12
14
16
18
20
22
24
26
28
30
35
40
45
50
55
60
75
90
105
120
150
180
210
240
270
300
330
360
390
420
450
480
510
540
570
WATER
DEPTH - FEET
23.50
23.50
23.52
23.54
23.58
23.57
23.61
23.65
23.67
23.68
23.70
23.70
23.70
23.71
23.71
23.71
23.75
23.75
23.78
23.79
23.81
23.80
23.81
23.81
23.67
23.75
23.80
23.82
23.82
23.82
23.80
23.80
23.82
23.82
23.91
23.91
23.91
23.82
23.80
DRAWDOWN
7.57
7.57
7.59
7.61
7.65
7.64
7.68
7.72
7.74
7.75
7.77
7.77
7.77
7.78
7.78
7.78
7.82
7.82
7.85
7.86
7.88
7.87
7.88
7.88
_ _
_
7.87
7.89
7.89
7.89
7.87
7.87
7.89
7.89
7.98
7.98
7.98
7.89
7.87
31
-------
Pump Test Measurements Test Well No. 1 - Pumping Well Page 2
TIME
8:35
9:05
9:35
10:05
10:35
11 :05
11 :35
12:05
12:35
1 :05
1 :35
2:05
2:35
3.05
3:35
4:05
4:35
5:05
5:35
6:05
6:35
7:05
7:35
8:05
8:35
9:05
9:35
10:05
10:35
10:47
ELAPSED
TIME - MINUTES
600
630
660
690
720
750
780
810
840
870
900
930
960
990
1020
1050
1080
1110
1140
1170
1200
1230
1260
1290
1320
1350
1380
1410
1440
1452
WATER
DEPTH - FEET
23.82
23.85
23.80
23.80
23.78
23.78
23.82
23.82
23.82
23.82
23.82
23.82
23.82
23.82
23.82
23.82
23.82
23.82
23.82
23.82
23.91
23.91
23.91
23.91
23.91
23.91
23.91
23.91
23.91
23.91
DRAWDOWN
7.89
7.92
7.87
7.87
7.85
7.85
7.89
7.89
7.89
7.89
7.89
7.89
7.89
7.89
7.89
7.89
7.89
7.89
7.89
7.89
7.98
7.98
7.98
7.98
7.98
7.98
7.98
7.98
7.98
7.98
32
-------
TABLE in
PUMP TEST MEASUREMENTS
OBSERVATION WELL NO. 1
50 FEET NNW OF TEST WELL NO. 1
DECEMBER 6, 1968
TIME
11 :08
11 :37
12:07
12:37
1 :07
1 :37
2:07
2:37
3:07
3:37
4:07
4:37
5:07
5:37
6:07
6:37
7:07
7:37
8:07
8:37
9:07
9:37
10:07
10:37
11:07
11 :37
12:07
12:37
1 :07
1 :37
2:07
2:37
3:07
3:37
4:07
4:37
5:07
5:37
6:07
6:37
7:07
ELAPSED
TIME - MINUTES
33
62
92
122
152
182
212
242
272
302
332
362
392
422
452
482
512
542
572
602
632
662
692
722
752
782
812
842
872
902
932
962
992
1022
1052
1082
1112
1142
1172
1202
1232
WATER
DEPTH - FEET
17.37
17.52
17.45
17.45
17.45
17.45
17.48
17.46
17.50
17.47
17.44
17.44
17.42
17.45
17.49
17.50
17.51
17.52
17.53
17.52
17.51
17.51
17.51
17.52
17.52
17.51
17.51
17.50
17.50
17.50
17.50
17.50
17.50
17.50
17.50
17.50
17.50
17.50
17.51
17.51
17.51
DRAWDOWN
1.77
1.92
1.85
1 .85
1.85
1.85
1 .88
1 .86
1 .90
1.87
1 .84
1 .84
1 .82
1 .85
1 .89
1 .90
1 .91
1 .92
1 .93
1 .92
1.91
1 .91
1 .91
1 .92
1 .92
1 .91
1 .91
1 .90
1 .90
1 .90
1 .90
1 .90
1 .90
1 .90
1 .90
1 .90
1 .90
1 .90
1.91
1 .91
1 .91
33
-------
Pump Test Measurements - Observation Well No. 1 - Page 2
ELAPSED WATER
TIME TIME - MINUTES DEPTH - FEET DRAWDOWN
7:37 1262 17.51 1.91
8:07 1292 17.52 1.92
8:37 1322 17.53 1.93
9:07 1352 17.58 1.98
9:37 1382 17.56 1.96
10:07 1412 17.56 1.96
10:37 1442 17.56 1.96
34
-------
TABLE IV
PUMP TEST MEASUREMENTS
OBSERVATION WELL NO. 2
150 FEET NNW OF TEST WELL NO. 1
DECEMBER 6, 1968
TIME
11 :09
11 :43
12:10 PM
12:40
1 :10
1 :40
2:10
2:40
3:10
3:40
4:10
4:40
5:10
5:40
6:10
6:40
7:10
7:40
8:10
8:40
9:10
9:40
10:10
10:40
11 :10
11 :40
12:10
12:40
1 :10
1 :40
2:10
2:40
3:10
3:40
4:10
4:40
5:10
5:40
6:10
6:40
7:10
ELAPSED
TIME - MINUTES
34
68
95
125
155
185
215
245
275
305
335
365
395
425
455
485
515
545
575
605
635
665
695
725
755
785
815
845
875
905
935
965
995
1025
1055
1085
1115
1145
1175
1205
1235
WATER
DEPTH - FEET
17.18
17.22
17.22
17.25
17.25
17.05
17.30
17.28
17.27
17.28
17.30
17.28
17.27
17.28
17.29
17.28
17.28
17.31
17.34
17.34
17.34
17.33
17.31
17.33
17.33
17.33
17.33
17.33
17.33
17.33
17.33
17.33
17.33
17.33
17.33
17.33
17.33
17.33
17.33
17.33
17.33
DRAWDOWN
1 .28
1 .32
1 .32
1 .35
1 .35
1 .15
1 .40
1 .38
1 .37
1 .38
1 .40
1 .38
1 .37
1 .38
1 .39
1 .38
1 .38
1 .41
1 .44
1 .44
1 .44
1 .43
1 .42
1 .43
1 .43
1 .43
1.43
1 .43
1 .43
1.43
1 .43
1 .43
1 .43
1 .43
1.43
1 .43
1 .43
1 .43
1 .43
1 .43
1 .43
35
-------
Pump Test Measurements - Observation Well No. 2 - Page ?.
ELAPSED WATER
TIME TIME MINUTES DEPTH - FEET DRAWDOWN
7:40 1265 17.33 1.43
8:10 1295 17.33 1.43
8:40 1325 17.33 1.43
9:10 1355 17.33 1 .43
9:40 1385 17.33 1.43
10:10 1415 17.33 1.43
10:40 1445 17.33 1 .43
36
-------
U)
16
17
18
19
25
OBSERVATION
WELL NO. 1
OBSERVATION
WELL NO. 2
f 1
till
25
50 75 100
DISTANCE IN FEET
125
150
UNDERGROUND DEMONSTRATION PROJECT
CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
MacKICHAN SMADSEN
Consulting Engineers
SOUTH ST. PAUL,MINNESOTA
68S4.I9
171-7
3-69
PLATE 19
E.A. HICKOK 8 ASSOCIATES
Consulting Hydrologisti
PUMP TEST DISTANCE
DRAWDOWN CURVE
Figure 19.
-------
Lo
00
15_
16J
SURFACE
V£> 00 ^J
1 1 1
o
id 20^
03
£ 21-
Q
22_
23-
24_
25
(
I OBSERVATION WELL NO. 2
L_^ ^_ \
/
OBSERVATION WELL NO. /
TEST WELL NO. 1
) 1^0 3^0 sio 720 gio 10^0 126.Q 1440
_ 15
_ 16
_ 17
_ 18''
-19 '
_ 20
- 21
- 22
- 23
- 2k
25
UNDERGROUND DEMONSTRATION PROJECT
TIME IN MINUTES CITY OF SOUTH ST. PAUL MINNESOTA
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030 DSL
Mac KICHAN 8 MADS EN
Consisting Enginetr;
SOUTH ST PAUL, MINNESOTA
68S4.20 EA HICKOK & ASSOCIATES
170-f """
3-69 PUMP TEST WATER LEVELS
PLATE 20
Figure 20.
-------
Computations of the test data indicate a coefficient of transmissibility
of 38,500 GPD per foot, a coefficient of storage of 2 x 10-4, and a
specific capacity of 18.8 GPM per foot of drawdown for that particular
well size and screen length.
Conclusions are based on the assumption that the subsurface conditions
found at drill hole TW-1 are indicative of the actual existing condition
for a radius of about 500 feet around TW-1.
39
-------
SECTION V
SUITABILITY OF TEST WELL SITE
The desirable characteristics of a site for demonstration for the
underground detention method includes ease of access to existing sewers;
a sufficient thickness, permeability, and capacity in subsurface forma-
tion to permit storage and demonstration of the method without con-
tamination of existing aquifers; a surface area of sufficient size for
the necessary settling basin and facilities for separation of solids
prior to injection of storm or combined solids underground; and a
sufficiently low elevation to make use of gravity flow.
Results of field investigations showed TW-1, the site of which the pump
test was conducted, appeared to fulfill all these requirements and it
is fairly remote from human activity so as to cause a minimum of di.s-
turbance if the demonstration project would have been continued into
Phase II. This site is also immediately upstream from the Sewage
Disposal Plant.
The results, based on the actual pump test at TW-1 and the observations
made at OW-1 and OW-2 (see Table V), show that for demonstration purposes
a series of five wells spaced at 200 foot intervals with pumping capaci-
ties of 200 GPM each could be constructed. See Plate 21.
Plate 22 is a detail drawing of a theoretical well plan that could be
used for each of the 5 well sites.
41
-------
TABLE v
PROJECTED OPERATING CONDITIONS
FIVE WELLS AT 200 FOOT SPACINGS
RECHARGE RATE 200 GPM PER WELL
SPECIFIC CAPACITY 25 GPM PER FOOT
Well
Numbers
1
2
3
4
5
Interference Cone
Recharge Cone
Total Cone Height
S.W.L.
1
-
1
1
1
1
5
8
13
15
-
.6
.5
.4
.3
.8
.00
.8
.6
2
1
-
1
1
1
6
8
14
15
.6
-
.6
.5
.4
.1
.0
.1
.6
3
1
1
-
1
1
6
8
14
15
.5
.6
-
.6
.5
.2
.0
.2
.6
4
1 .
1 .
1 .
--
1 .
6.
8.
14.
15.
4
5
6
6
1
0
1
6
5
1
1
1
1
-
5
8
13
15
.3
.4
.5
.6
-
.8
.0
.8
.6
Water Depth 1.8 1.5 1.4 1.5 1.8
42
-------
5 -
10 -
Recharge
water level
OJ
-------
Recharge from
settling pond
Horizontal
\ pump
Grout
surface to
20' depth
12" Diameter
ca s i n g
o°o
ifo
12" Diameter
x 20' long
wel1 screen
Armco i ron
Turbi ne
Pump
Discharge to
treatment plant
a -
00
9 .
A '*
Gravel
pack
UNDERGROUND DEMONSTRATION PROJECT
CITY OF50UTH ST.PAUL MINNESOTA
FEDERAL VWER POLLUTION CONTROL ADMINISTRATION
DEMONSTRATION GRANT PROJECT NO. 11030* DSL
MocKICHANaMADSEN
Consulting Engint«ri
SOUTH ST. PAUL,MINNESOTA
68S4.22
I7O-7
3-69
PLATE 22
EA HICKOK 8 ASSOCIATES
CorauM* Hytfreloolst*
THEORETICAL WELL CONSTRUCTION
DIAGRAM
Figure 22.
44
-------
SECTION VI
SOLIDS SEPARATION INVESTIGATION
Included in the scope of work for Phase I of the Demonstration Project
was an investigation, analysis and discussion of methods of solids
separation which might be used for storm and combined sewage in
Phases II and III, prior to injection of the effluent underground.
There are several design parameters which have to be established before
final design or recommendations for separation for solids can be made.
Included in these parameters are such things as the rate in total
volume of storm flow to be handled, the rate at which the storm flow
can be injected into the underground strata and the solids volume con-
tained in the storm or combined flow in terms of gradation of solids
and type of solids. Also, a specific limitation on solid size of
concentration would have to be determined for the hydraulic volumes
to be injected in the subsurface strata.
For injection of the storm or combined flow into the subsurface strata
there are two extreme conditions, the first being that all storm-combined
flow be stored in surface reservoirs and withdrawn at a constant rate
for injection into the subsurface strata, and the second that all storm
and/or combined flow would be injected directly into the subsurface
strata without storage. There would, of course, be an infinite number
of variations between the two extremes. A method which could be
practiced for solid removal is sedimentation or settling of solids in
detention basins with or without the flow receiving chemicals to
assist in flocculation and sedimentation. Sedimentation is accomplished
with a due consideration to velocity control, surface settling rate
and detention time. Additional solids removal could be separated by
straining or filtration of water which could include use of sand
filters or fine screens with a certain size limitation of solids pas-
sage for the screen. A combination of sedimentation and screening
could be practiced depending upon solids concentration or particle
size limitation for wastewater to be injected into the subsurface
stratus.
The preliminary investigation included the assumption that all or
portions of the storm and/or wastewater would be stored in surface
reservoirs with solids separated prior to injection into the under-
ground strata. The problem then resolves to methods of removing solids
from surface reservoirs which settle during storage plus possible fil-
tering or settling of effluent from the basins to a specific quality
prior to discharge to the injection wells plus handling of solids
separated in the process.
45
-------
Soils can be classified by particle size as follows:
Gravel - larger than 2.0 millimeters
Coarse sand - 2.0 to 0.42 millimeters
Fine sand - 0.42 to 0.05 millimeters
Silt size - 0.05 to 0.005 millimeters
Clay size - smaller than 0.005 millimeters
A 200 mesh U. S. Standard sieve has an opening of 0.074 millimeters.
Classification of fine sand can be made to 0.074 millimeters rather
than 0.05 millimeters, as previously noted. The law of averages
narrows the usual range of variation of the true specific gravity of
soils to values between about 2.55 and 2.75.
Specific gravity of organic solids in combined sewage flows can range
from less than 1.0 (flotables such as grease) to 2.65 (soil).
Sedimentation efficiency depends upon many variables such as temperature
of water, specific gravity of materials in suspension and size and shape
of suspended particles.
Sedimentation of 4 micron clay Sp. gr. 2.65 in 10° C (50° F.) water can
be accomplished at an overflow rate of 52 gallons/S.F./day. At water
temperature of 32°F. the overflow rate would be 38 gallons/S.F./day.
Sedimentation alone for organic solids removal cannot be accomplished
to consistently satisfy a maximum particle size of 5 microns. Mechani-
cal screening with micro-screens can, however, be done, as commercially
available screens have a screening capability of 23 to 25 microns. It
is therefore concluded and recommended that if waters to be injected
into the underground strata contain organic solids, provisions be made
in the solids removal system to include or add chemical mixing and
flocculation facilities followed by sedimentation basins and water
filtration facilities, such as rapid sand, mixed or dual made filters.
It is noted that should chemical treatment be practiced, the chemical
balance of the water may have to be re-established prior to subsurface
injection.
Other recommended facilities should include trash screens and facili-
ties for grit removal.
Trash screens recommended are mechanically cleaned type with screen
with 1-inch clear openings. Screen recommended is a front cleaned
cable operated unit. Debris removed should be hauled to a sanitary
landfill. All flow should be screened when received.
Grit removal units recommended would be sized to remove 10070 of 150
mesh (104 micron) material. Facilities proposed would be two units
the first sized to remove 10070 of 35 mesh grit and sized at 80,000
46
-------
gallons/S.F./day. Grit would be removed from the basin with either a
dredging pump or overhead hoist with a clam shell. The second or sub-
sequent unit would be sized for 1007» removal of 150 mesh materials.
Basins would be sized at 14,000 gallons/S.F./day and be equipped with
traveling bridge collectors with bottom scrapers and water jets to
remove settled material. Settled material to be pumped to a cyclone
separator with effluent to sanitary sewer. Grit recovered in either
or both units to be used as fill material, or land filled as organic
contents dictates.
Storage basins would be sized to contain all waters until disposal.
Size of basins would be dependent upon inflow and outflow rates.
Storage basins would be drained to a sump for return as settled
materials to the grit recovery units. Provisions should be made
either to allow flushing of settled material to the sump or to allow
operation of dragline or front-end loader to remove settled materials.
Dependent upon settleability of solids, provisions could be made to
withdraw pond effluent for subsurface injection or subsequent chemical
flocculation, sedimentation, filtration, and injection. Should pond
effluent be withdrawn for direct injection, scum baffles and/or fine
screens should be provided to prevent floating material from entering
the injection system.
Chemical mixing and flocculation should be accomplished in a quick mix
basin with mechanical mixer, 30 seconds minimum detention, to rapidly
dispense chemicals throughout the water. Mixing should be followed by
flocculation basins sized to provide 30 minutes detention with velocity
control by mechanical agitators moving 0.5 to 2.0 feet per second.
Lime and alum chemical feed equipment and chemical storage facilities
are required plus chlorination equipment for possible use in applying
chlorine to raw water or prior to filtration.
Sedimentation after chemical flocculation should be sized on 4 hours
detention time. Basins should be equipped with mechanical sludge
removal equipment. Quite possibly, basins used as grit recovery units
could be used as sedimentation basins during periods of no raw inflow.
Sludge from basins could be discharged to the sanitary system for re-
moval, at the sanitary treatment plant, and possibly be beneficial to
sanitary sedimentation due to coagulants contained.
Filtration units should follow sedimentation tanks to insure removal
of all 5 micron and larger particles. Mixed media or dual media
filtation units operated at 5 gpm/S.F. should provide adequate
solids removal. Backwash water from units should be returned to
storage ponds.
A 1,000 gpm pilot plant for solids recovery and injection was con-
sidered. The following solids recovery facilities are recommended
for consideration.
47
-------
Trash screen, % inch clear openings, hand cleaned, size for a maximum
flow through velocity of 3 fps.
Grit Recovery, size for 100% removal of 150 mesh (104 micron) surface
settling rate 14,000 gallons/S.F./day. Use tank 10' x 10.3' x 7.0 SWD
with hopper bottom with solids removed from the bottom either by gravity
to a grit washer or pumped to a grit washer or cyclone. Dispose of
solids in landfill.
Storage Basin. At a flow rate of 1,000 gpm, 1,440,999 gallons/day
would be handled. For removal of all inorganic materials 5 microns
and larger with specific gravity of 2.65 at a water temperature of
32°F, a settling basin of 38,000 square feet is required. Basin
should be baffled to prevent short circuiting of flow with a maximum
basin water velocity of 0.5 feet per minute. Basin effluent should
pass over a weir at a maximum flow rate of 10,000 gallons/L.F./day.
A scum baffle should be provided at the weir to prevent flotable
materials leaving the basin.
Should chemical flocculation, sedimentation and filtration be required
to remove all particles larger than 5 microns, the following is
suggested.
Quick Mix - Use 500 gallon tank with mixer. Add synthetic polymer as
flocculant.
Flocculation Unit - Non-mechanical, use baffled channel to provide 1 fps
velocity for 30 minutes. Use 1.5' water depth x 3.0' wide channel with
alternate 1.5' x 1.5' baffle plates @ 1.5' 0 center to center spacing.
Sedimentation Unit - Non-mechanical, use basin 10' deep x 20' wide x 160'
long with scum baffle and 72 L.F. of overflow weir. Drain to sump for
solids return to grit unit or to sanitary sewer.
Filtration Unit - Use dual media or mixed media loaded at 5 gpm/S.F.
Return backwash water to storage pond for subsequent settling. Consider
automatic back gravity filter such as Eimco Type SUBG.
Storm water solids captured by screens or settling can possibly be used
as fill material. Solids recovered from combined sewer would have to
be land filled or disposed of with other city sanitary waste solids.
Materials flushed from filters could be re-cycled through the grit-silt
removal or be discharged to the sanitary system.
48
-------
SECTION VII
DISCUSSION OF RESULTS
Phase I of this report has only attempted to locate a site suitable
for subsequent testing. In order to ascertain the feasibility of the
method under operating conditions and to determine cost factors,
Phases II and III would have to be completed. Due to the inadequate
availability of underground storage capacity, it was decided not to
proceed with Phases II and III.
A recently completed study on combined sewage system separation
and treatment for South St. Paul, prepared by Henningson, Durham &
Richardson, evaluated 4 alternate methods of handling the pollution
problems caused by discharging combined storm water and wastewater
into the Mississippi River during periods of high surface runoff.
The methods considered in the study are referred to as Detention &
Treatment; Schemes A, B, and C, and Total Separation.
The study recommends Total Separation of the systems based on economics
and the lack of available land for surface detention basins. See
Appendix A for data relating to the "Combined Sewerage System Separation
and Treatment South St. Paul, Minnesota" study.
49
-------
SECTION VIII
ACKNOWLEDGEMENT
The City of South St. Paul, Minnesota, would like to acknowledge the
people and organizations whose efforts and knowledge are incorporated
into this study.
City of South St. Paul
Mr. John P. Badalich
Mr. Donald R. Peterson
Mr. Thomas J. McMahon, City Engineer
Mr. Richard A. Hudak, Engineering Administrator
Consultants
MacKichan & Madsen, Consulting Engineers
Henningson, Durham & Richardson, Consulting Engineers
Eugene A. Hickok & Associates, Consulting Hydrologists
U.S. Environmental Protection Agency
Minnesota-Wisconsin District Office
Mr. Clarence C. Oster
51
-------
SECTION IX
GLOSSARY OF PERTINENT TERMS
Geophysical - The study of the physical characteristics and properties
of the earth. In this study dealing primarily with the use of seismic
and electrical resistivity methods.
Geological - The science which deals with the history of the earth and
the materials which it is composed of. In this study dealing primarily
with the alluvial strata.
Hydrological - The branch of hydrology that treats ground water; its
occurrence and movements; its replenishment and depletion; the
properties of rocks which control ground water movement and storage;
and the methods of investigation and utilization of ground water.
Combined Sewage System - A system whereas during dry weather conditions,
the sewer conduits direct all sanitary wastewater to the sewage treat-
ment plant during surface runoff conditions due to precipitation or
melting snow, the water is collected in the same sewer conduit as the
sanitary wastewater. All flows exceeding capacity of the conduit lead-
ing to the treatment plant overflow into a pond, lake, stream, river,
etc.
Piezometer Wells - An instrument for measuring pressure head in a
conduit, tank, soil formation, etc. In the case of the study, the
piezometer wells were used to observe the fluctuation of the water
level in the soil formations to be tested, and also to allow sampling
of the water for analysis purposes.
Chemical Flocculation - The introduction into a sewer treatment
process a coagulant to form small gelatinous masses to aid in solids
removal.
Electrical Resistivity Soundings - A method by which earth and rock
materials can be identified by their reaction to the flow of a direct
current of electricity. This is an action of electrolytic nature in
which moisture in the soils and rocks, together with dissolved im-
purities, gives to the several materials characteristic resistances
to the current flow. These characteristic resistances may be used for
locating and identifying subsurface formations. Ordinary moist soils
containing moderate amounts of clay or silt, with some electrolytic
agent more or less active, have a comparatively low resistance. In
contrast, sand, gravel, extremely dry, loose soils and solid rock
usually have high resistivity values.
53
-------
SECTION X
APPENDICES
A. Combined Sewage System Separation and Treatment, South
St. Paul, Minnesota.
55
-------
APPENDIX A
Separation and Treatment of Combined Sewerage System, South St. Paul,
Minnesota, by Henningson, Durham and Richardson, Omaha, Nebraska.
TOPICAL SUMMARY
1. Existing sewage collection system is grossly overloaded for storm
water flow in many locations.
2. The dilutional effect of storm water on the sanitary sewage during
times of overflow to river is insufficient to abate pollution,
particularly from the standpoint of disease bacteria.
3. Either Total Separation - with storm water discharging to the river
and all sanitary flow treated at central treatment plant before
discharge to the river - or sufficient treatment of the combined
sewage is required to satisfactorily abate pollution of the river.
4. Total separation and three methods of treatment were studied in
detail. Other possible methods of treatment were discarded as not
economically feasible.
5. Cost comparisons are as follows:
Detention and Treatment
Detention and Treatment
Detention and Treatment
Total Separation
Method "A"
Method "B"
Method "C"
$4,838,367
$5,609,390
$3,558,782
$4,020,745
6. The additional storm sewer pipe required to bring the storm drainage
system up to a theoretical ten-year storm capacity are estimated at
a cost of $960,372. This additional sewer pipe is not required for
separation and is illustrated for informational purposes only.
7. Total separation is recommended for the following reasons:
(a) Treatment under any of the three (3) methods would
create odor problems due to solids residue in detention
ponds along the river. These detention ponds would
create potential blight areas, particularly to new
industrial expansion along the river front.
(b) To create detention basins of the size required away
from the populated area is totally unfeasible due to
high costs of extremely large trunk outfall sewers
required.
56
-------
(c) Treatment under the least costly Method "C" would only be
partial. At times of low storm flow, the dilution factor
would not be high enough to adequately reduce BOD and solids
content.
Note: Construction cost estimates have not been escalated for future
materials or labor costs.
(d) Elimination of storm water surge to the existing sewage
treatment facilities will reduce treatment costs and allow
the present plant to operate more efficiently.
(e) Separation of storm water from the sanitary sewer system will
eliminate public health hazards of back-up and overflow of
sanitary sewage into basements and onto streets.
(f) Total separation costs are lower than two of the three methods
of treatment and only 6% higher on a 20-year annualized cost
basis than the third Method "C".
8. Sources of financing for the separation project are recommended as
follows;
FWPCA - Sewer Separation Demonstration Grants
DHUD - Community Facilities Construction Grants
DHUD - Urban Renewal Construction Grants
DHUD - Industrial Development Grants
General Obligation Bonds
Sewer Use Revenue Bonds
State Aid - Street Improvements
9. The following is the recommended expenditure schedule for the
construction of storm sewers and sanitary sewers, which will be
required in order to provide separation of storm flows from
sanitary flows.
Summary of Costs on a Yearly Basis:
Capital Engin., Admin., Legal, Total Project
Year Improvements Interest & Contingencies Cost
1970 $206,180 $ 51,545 $ 257,725
1971 338,518 84,629 423,147
1972 650,577 162,644 813,221
1973 653,722 163,430 817,152
1974 682,071 170,518 852,589
1975 685,529 171,382 856,911
$4,020,745
57
-------
10. The construction costs of sewers within State Aid Street
Improvement Boundaries for 1970 equals $107,985. The Urban
Renewal Grant for sewer construction in 1971 approximately
equals $159,000.
58
-------
ALTERNATE METHODS OF TREATMENT
TREATMENT OF COMBINED SEWAGE
1. General
Three different schemes of ponding have been considered. Combining these
different schemes for various systems is not considered practical since
each proposes allowing the passage of different basic mixtures of com-
bined sewage to the river. In each scheme, the flows to the river are
to be chlorinated. Two of the three schemes provide for treatment of
temporarily stored combined sewage at the existing treatment plant.
The third scheme provides for chlorination and a short detention ptior
to passage into the river.
2. Scheme A
In this scheme the combined sewage up to a maximum of two and one-half
(2^) times the average daily flow will be routed directly to the treat-
ment plant for treatment. Flows between two and one-half(2%) and ten
(10) times the average daily flow will be routed to a pond for temporary
storage. Flows greater than ten (10) times the average daily flow will
be routed directly to the river after chlorination. Assuming that the
average daily flow of domestic sewage contains 220 ppm BOD and the storm
runoff contains 20 ppm BOD that combined sewage routed directly to
the river would contain 35 ppm BOD. Currently the BOD for storm water
is higher than 20 ppm. Any combined sewage flows routed to the river
will be chlorinated. The symbol Qsa is used herein to indicate 2% times
the average daily sewage flow (25070) . 3 Qsa represents 750% of the
average daily flow or the amount of storm flow required to dilute the
sanitary flow. The total wet weather flow is identified as 4 Qsa = Qsa +
3 Qsa = 10 times the average daily flow.
Controls will be liquid level sensing controlled gates. When the flow
reaches a depth that produces a flow of 2% times average daily flow the
gate to the pond opens, the gate to the interceptor closes, and the
pumps are started. When the flow reaches a depth that produces a flow
of 10 times average daily flow the gate to the river opens, the gate to
the pond closes, and the chlorinator is started. The reverse control
operation will take effect as the flow diminishes.
Ponds are sized to contain a constant rate equal to 10 times the average
daily flow for a period of 48 hours during which time the rate of pump-
ing equals the plant hydraulic capacity.
The combined sewage left in the pond after a rainstorm will be pumped
to the plant for treatment during the evenings and week-ends. The com-
bined rates of pumping from the ponds will be controlled so as not to
exceed the hydraulic capacity of the plant.
59
-------
Since there are no available areas to construct ponds to serve the
Wentworth Avenue and Grand Avenue systems, they have not been included
for ponding of combined sewage. Also, these two systems are located
a considerable distance from the nearest downstream pond area and would
require more than 7,000 feet of new combined sewer line to connect them
to the nearest pond area.
Plate 23 shows a schematic layout of this proposed combined sewage pond
system.
The following table indicates the basic design required for ponding of
combined sewage under Scheme A for those drainage systems under con-
sideration:
System
Stanley
Ave.
2.5 x Avg. Daily Flow cfs 0.780
10.0 x Avg. Daily Flow cfs 3.120
Max. Flow with 10 Yr. Rain 114.63
Intensity cfs
Pond Volume - Ac-Ft. 11.14
Pumping Capacity Max. GPM 490
Chlorination Capacity Lbs/Day 800
Grit Removal Chamber Sq. Ft. 144
Time Required to empty pond
Hrs. 145
Line Size to Pond In-Dia. 15
Line Size to Overflow
In-Dia. 15
Chlorination Pond Size
Length Ft. 513
Central Ave.
& Simons Ravine
4.585
18.340
358.39
69.11
3040
2500
345
145
30
30
713
Sixth
Street
1.897
7.560
202.09
Maltby
Street
6.914
27.660
772.85
29.17
1285
1400
350
145
18
18
748
104.20
4600
5650
1275
145
30
30
865
It will be necessary to construct additional interceptor line capacity
and increase existing lift station capacity in order to pass the flows
during periods when the ponds are being emptied by pumping. The following
additions to the present interceptor system will be required under this
scheme.
a. Increase pumping capacity from 350 gpm to 800 gpm in the existing lift
station located downstream of Butler Avenue.
b_. Between Central Avenue and Wentworth Avenue outfall lines, construct
2,710 feet of 21" sewer parallel with the existing interceptor.
£. Between Wentworth Avenue and Grand Avenue outfall lines, construct the
following lines parallel to the existing interceptor: 1,360 feet of 10",
250 feet of 15" and 150 feet of 18" sewers parallel with certain portions
of the existing interceptor.
60
-------
Cmitrnl MH
Control MH
Chlorine Feeder
Pump Station
Chlorine Detention
Pond
Storaqe Pond
To River
SCHEME A
COMBINED
SEWAGE TREATMENT FACILITIES
(TYPICAL)
(PONDING 4- QSA)
SOUTH ST. PAUL, MINNESOTA 1969
Plate 23
Figure 23.
61
-------
Flow to be stored to pass thgough a grit removal basin to remove 1007=
of 150 mesh and larger grit sized at 14,000 gallons/SF/day. Solids
settled to be removed with an overhead traveling bridge hoist with clam
shell. Fine settled material to be pumped to a cyclone separator with
effluent to the sanitary sewer. Solids recovered to be hauled to a
sanitary landfill. Solids contained in the cyclone effluent to be dis-
charged to the sanitary plant for removal with other sanitary solids.
3. Scheme B
In this scheme the combined sewage up to a maximum of two and one-half
(2%) times the average daily flow will be routed directly to the plant
for treatment. Flows between two and one-half (2%) times the average
daily flow and the maximum peak for a 10 year rainfall intensity will
be routed to the pond for temporary storage. Flows greater than the
maximum peak for a 10 year rainfall intensity will be routed to the river
after chlorination in the detention pond.
Controls will be similar to Scheme A except for the amounts routed to
the plant, pond or river.
Ponds are sized to contain a 100-yr. volumetric rainstorm (6" of preci-
pitation in 24 hours), following a 24-hour constant rate flow of 10 times
the average daily flow during which time the rate of pumping equals the
plant hydraulic capacity.
The combined sewage lift in the pond after a rainstorm will be pumped to
the plant for treatment during the evening hours and week-ends. The
combined rates of pumping from the ponds will be controlled so as not
to exceed the hydraulic capacity of the plant.
Plate 24 shows a schematic layout of this proposed combined sewage pond
system.
The following table indicates the basic data required for ponding of
combined sewage under Scheme B for the drainage system under consideration:
62
-------
Control MH
To Rlv»r
Control MH
Chlorine Feeder
Grit Removal
35 Mesh
Brit Removal
ISO Mesh
Pump Station
Storage Pond
SCHEME B
COMBINED
SEWAGE TREATMENT FACILITIES
(TYPICAL)
(PONDING 2AHR-IOOYEAR STORM)
SOUTH ST. PAUL, MINNESOTA 1969
Figure 24.
63
-------
2.5 x Avg. Daily Flow cfs.
10.0 x Avg. Daily Flow cfs.
Max. Flow with 10-yr. Rain-
fall Intensity cfs.
Pond Volume Ac-Ft.
Pumping Capacity Max. GPM
Chlorination Capacity
Lbs/Day
Grit Removal Chamber Sq.Ft.
Time Required to empty Pond
Hrs.
Line Size to Pond In-Dia.
Line Size Pond Overflow
In-Dia.
Chlorination Pond Size
Length-ft.
Stanley
Ave.
0.780
3.120
114.63
25.24
670
800
6170
228
60
60
513
System
Central Ave.
& Simons Ravine
4.585
18.340
358.39
69.10
1930
2500
19150
228
90
90
713
Sixth
Streej:
1.897
7.560
202.09
42.90
1200
1400
10810
228
66
66
748
Maltby
Street
6.914
27.660
772.85
198.67
5550
5650
41600
228
120
120
865
It will be necessary to construct additional interceptor line capacity and
increase existing lift station capacity in order to pass the flows during
periods when the ponds are being emptied by pumping. The following ad-
ditions to the present interceptor system will be required under this
scheme.
a. Increase pumping capacity from 350 gpm to 1,000 gpm in the existing
lift station downstream of Butler Avenue.
b_. Between Central Avenue and Wentworth Avenue outfall lines, construct
2,710 feet of 18" sewer parallel with the existing interceptor.
c. Between Wentworth Avenue and Grand Avenue outfall lines, construct
250 feet of 10" and 150 feet of 18" sewers parallel with certain portions of
the existing interceptor.
Grit removal unit recommended would be sized to remove 100%, of 150 mesh
material. Facilities proposed would be two units, the first sized to remove
100% of 35 mesh grit and sized at 80,000 gallons/S.F./day. Grit would be
removed from the basin with overhead hoist with a clam shell. The second
or subsequent unit would be sized for 100% removal of 150 mesh materials.
Basins would be sized at 14,000 gallons/S.F./day and be equipped with
traveling bridge collectors with bottom scraper and water jets to remove
settled material. Settled material to be pumped to a cyclone separator
with effluent to sanitary sewer. Grit recovered in either or both units
to be used as fill material or land filled as organic content dictates.
64
-------
Storage basins would be sized to contain all waters until disposal. Storage
basins should be drained to a sump for return of settled material to the
grit recovery units. Provisions to be made either to allow flushing of
settled material to the sump or to allow operation of dragline or front-
end loader to remove settled material.
4. Scheme C
In this scheme, the combined flow up to a maximu of two and one-half (2%)
times the average daily flow will be routed directly to the treatment plant.
Flows exceeding two and one-half(2%) times the average daily flow will be
chlorinated and routed to the river.
Chlorination before routing to the river will be done by injecting chlorine
in the outfall line ahead of the chlorine detention pond. The chlorination
ponds are sized to allow for fifteen (15) minutes detention time before the
sewage is allowed to pass to the river. The same size of chlorination
detention ponds will be used in Scheme A for each system. In Scheme B,
flows exceeding the maximum peak fora 10-year rainfall intensity are to
be chlorinated in the detention pond with overflow to the river.
Plate 25 shows a typical chlorination detention pond.
The following Table indicates the size of chlorination detention ponds for
each system.
Bottom Width Length
Ft. Ft,
Stanley Avenue 50 513
Central Avenue 75 713
Sixth Street 55 748
Maltby Street 100 865
EXISTING SEWAGE TREATMENT PLANT
The City of South St. Paul has a sanitary sewage treatment facility sized
for an average daily flow of 17.5 MGD, with maximum capacity of 25 MGD.
Plate 26 shows the anticipated hydraulic loading to the treatment facility
during an average weekday, while industry is in operation, and a typical
Saturday or Sunday.
As one means of treatment of combined flows intercepted and stored in
retention ponds, it is suggested the night time and week-end hydraulic
capacity of the existing sanitary treatment facility be utilized to
receive and treat combined sewage. It has been calculated that approxi-
mately 15.4 MGD can be discharged to the sanitary plant on Saturday and
Sunday, to load the plant to a 25 MGD hydraulic capacity. It has also
been calculated that the treatment plant could be loaded to 25 MGD during
week days from the period of approximately 10:00 P.M. to 8:00 A.M. during
off peak hydraulic and organic loads to the facility. Approximately 5 MGD
can be discharged to the sanitary plant on a given week day. Total weekly
sanitary treatment facility capability utilized would then equal approxi-
mately 55 MG/week.
65
-------
Plan
NO SCALE
l g"
Max. Water Level ^\
Q
1% Slope -~- s
//^^
40
t===
4-
2D
~- / % Slope
~ ^fiM ' '
40
l^^~^1
Section A-A
NO SCALE
6 Cone rete
D-Outfall Pipe Diameter
SCHEME "C"
COMBINED
SEWER CHLORINE DETENTION
POND
(TYPICAL)
SOUTH ST. RAUL, MINNESOTA
1969
Figure 25.
66
-------
MAXIMUM HYDRAULIC CAPACITY
25
i
I
b.
20
COMBINED SEWAGE DISCHARGE
WEEKEND \ \ \ \ \
WEEKDAY \\\\\
8 9 10 II 12 I 3 3 4 5 6 7 8 9 10 II 12 I 2345678
P.M.
TIME
COMBINED SEWAGE DISCHARGE
SEWAGE TREATMENT PLANT
SOUTH ST. PAUL, MINNESOTA
Figure 26.
67
-------
It is anticipated that pond storage of combined sewage will effect a
35% reduction in BOD and a 65% reduction in suspended solids. Combined
sewage received by the City Sanitary Treatment Facility should have BOD
and suspended solids reductions approximately equal to that given
sanitary sewage received by the facility.
1. Chlorination
The Minnesota Pollution Control Agency (MPCA) criteria that the total
coliform group organisms be limited to 5,000 most probable number per
100 milliliters when applied to combined sewage is a difficult parameter
to satisfy. It is estimated that an average contribution of 200 million
coliform/person/day is contributed to the system. In raw form, this is
approximately 52,000,000/100 millimeter MPN. A dilution factor of
10,000:1 would be required to satisfy the requirement of 5,000/100 milli-
meter MPN. The problem of effective bacterial reduction of discharge from
combined systems can be solved by either of two methods or a combination
of the two. The most effective method is to separate completely the raw
sewage and collect it for treatment at sanitary facilities. The other
extreme would be to chlorinate all the sewage prior to discharge to the
receiving stream.
With regard to the required chlorine dosages to destroy effectively
coliform bacterial in raw sewage, experiments indicate that a dose of
20 to 30 mg/liter is effective with a 15 minute contact period. Experi-
ments also show that required chlorine dose decreases substantially with
increased dilution of the sewage. The following information is presented
regarding dilution and dosage of chlorine in mg/liter.
(2)
Dilution in Dry Weather Flow Chlorine Pose - mg/liter
10 8.5
25 2.3
50 1.6
100 1.3
As previously stated, a contact period of approximately 15 minutes is
required with chlorine dosage made proportional to flow and dilution
and chlorine residual measured after the contact period to establish
dosage and substantiate disinfection of combined sewage.
Table VI is a Frequency of Runoff tabulation sheet.
Table VII is a tabulation of dry weather and combined flows in multiples
of dilution with chlorine dosages noted and chlorine required in terms
of pounds/day feed rate.
68
-------
Table No. VI
Column No.
Stanley Ave.
Simons Ravine
Central Ave.
Wentworth Ave.
Grand Ave.
6th Street
Maltby Street
A
CXA
Qsa
250%
DWF
cfs
3
Qsa
Frequency of Runoff
j> 6_ 11
Storm % %
Flow (a Storm of Time of Time
intensity of Intensity Rainfall Rainfall
0.01"/ to Produce in Excess Less than
hour 3 Qsa of 3 Qsa 3 Qsa
cfs
Inches/Hr. Runoff
Runoff
% Reduction
in Combined
Discharge to
River
Intercepting
3 Qsa
(CxAxO. 0 1' '/hr) (|. fffi8 ) (FromFig7)(3. 4-Col7) (Column 8 + 3. 4)
;. 6 50.5 0.78 2.34 0-50 0.047 1.4 2.0 59
252 138.2 4.58 13.74
674 356.0 4.92 14.76
188 107.6 2.99 8.97
145 85.8 1.90 5.70
720 397.3 6.91 20.73
1.
3.
1.
0.
3.
38
56
08
86
97
0.
0.
0.
0.
0.
099
041
083
066
052
0.
1.
0.
1.
1.
75
7
85
0
2
2.
1.
2.
2.
2.
65
7
55
40
2
78
50
75
70
65
A = Area, in Acres
C = Coefficient of Runoff
DWF = Dry Weather Flow
cfs = Cubic Feet per Second
Qsa = 250% x DWF (cfs)
3 Qsa = Storm Flow
250 Gal/Capacity/Day
750 Gal/Capacity/Day
Combined Flow
1000 Gal/Capacity/Day = 4 Qsa
-------
Table VII
Cl. @ Cl. @
DWF 10 DWF
#/day rate 10 #/Day
DWF @ 25 DWF Rate @
cfs mg/1 cfs 8.5 mg/1
Stanley 0.31 43 3.1 142
Ave.
Central 1.83 252 18.34 840
Ave.
Went- 1.97 270 19.69 900
worth
Ave.
Grand 1.19 165 11.97 550
Ave.
Sixth 0.75 105 7.56 350
Street
Maltby 2.76 380 27.66 1265
Ave.
DWF = Dry Weather Flow
cfs = Cubic Feet per Second
Cl = Chlorine
Disinfection
Cl. @ Cl. @ Cl. @ 10 10 yr.
25 DWF 50 DWF 100 DWF yr. Cl. @
25 #/Day 50 #/day 100 #/day Max. Max.
DWF @ 2.3 DWF @ 1.6 DFW (§1.3 Flow Flow
cfs mg/1 cfs mg/1 cfs mg/1 cfs #/day
7.75 96 15.5 133 37.0 216 114 800
46 570 92 790 183 1280 353 2470
49 608 98 845 197 1380 532 3720
30 372 60 515 119 834 262 1830
19 236 37.5 322 75 525 200 1400
69 855 138 1190 276 1930 765 5650
-------
1
Accession Number
w
5
2
Subject Field & Group
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
Organization
City of South St0 Paul, Minnesota
Title
TEMPORARY DETENTION OF STORM AND COMBINED SEWAGE IN NATURAL
UNDERGROUND FORMATIONS
10
Authors)
Hudak, Richard A,
McMahon, Thomas J_
16
Project Designation
EPA, WQO Contract No. 11030DSL
21
Note
22
Citation
Environmental Protection Agency Report Number EPA-R2-73-242,
May 1973.
Descriptors (Starred First)
Combined Sewage, Underground Detention
Identifiers (Starred First)
* Detention of Combined Storm and Sanitary Sewage in
Underground Formations
27
Abstract
The object of this study was to demonstrate the feasibility of
temporarily detaining storm and combined sewage in natural underground
formations.
Five sites were selected for subsurface geological and geophysical
investigation for the purpose of determining which site possessed sub-
surface conditions most suitable for storing and retrieving storm and
combined sewage
The geophysical work required six resistivity soundings as well
as resistivity survey involving five traverses. Based on this work,
three sites were selected for test boring, A four-inch (4") test
boring was made at each of these three sites. Two of the sites were
too shallow for later demonstration of the technique,, The third site
was selected for the demonstration.
Abstractor
Richard A. Hudak
Institution
City of South Saint Paul, Minnesota
VVR:102 (REV. j u L Y 1969)
SEND. WITH COPY OF DOCUMENT, TO: WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D0 C. 20240
* GPOS 1970 389-930 J
------- |