PB83-217745
Evaluation of Catchbasin Performance for
Urban Stormwater Pollution Control
Environmental Design and Planning, Inc.
Boston, MA
Prepared for
Municipal Environmental Research Lab,
Cincinnati, OH
Jun 83
U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
-------
EPA-600/2-83-043
June 1983
EVALUATION OF CATCHBASIN PERFORMANCE FOR
URBAN STORMWATER POLLUTION CONTROL
Gerald L. Aronson
David S. Watson
Wil11am C. Pisano
Environmental Design & Planning, Inc
Boston, Massachusetts 02134
Grant No. R-804578
Project Officer
Richard Field
Wastewater Research Division
Municipal Environmental Research Laboratory (Cincinnati)
Edison, New Jersey 08837
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
-------
TECHNICAL REPORT DATA
(Please read Inwnjct ions on the reverse before completing)
I REPORT NO 2
EPA -600/2-83-043
3 &fLgNT’S ACCESSION NO
1DO5 21774 1 r
4 TITLE AND SUBTITLE
B REPORT DATE
EVALUATION OF CATCHBASIN PERFORMANCE FOR URBAN
STORMWATER POLLUTION CONTROL
June 1983
B. PERFORMING ORGANIZATION CODE
REPORT NO
7 AUTHOR(S)
B PERFORMING
Gerald L. Aronson, David S. Watson, and William C.
Pi sano
ELEMENT NO
9 PERFORMING ORGANIZATION NAME AND ADDRESS
10 PROGRAM
Environmental Design & Planning, Inc.
19 Fordham Road
Allston, Massachusetts 02134
1 1-B0e 1Tn . IT/GRANi’NO
R-804578
12 SPONSORING AGENCY NAME AND ADDRESS
13 TYPE OP REPORT AND PERIOD COVERED
Municipal Environmental Research Laboratory- Cm.,
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
OH
14 SPONSORING AGENCY CODE
EPA/600/14
15 SUPPLEMENTARY NOTES Project Officer: Richard Field, Chief, Storm and Combined Sewer
Program. Coml. (201) 321-6674; FTS 340-6674.
lB ASS ’
ThIs report siesnarises the results of a field oriented data collection effort aired at evaluating the performance
and utility of catchbasins from a pollutIon control standpoint me project was fanctisnal ly dl vided into three phases.
with the fIrst being field data collection efforts and the last relegated to data reduction and analysis
In the first phase of field work, three catchbasies In the West Rosbury section of Boston were selected from a can-
didate list over 40 sites throughout the city The catchbasins chosen illustrated a diversity of land use and trsffit
situations, as well us design type Each cutchbasln was then cleaned using traditional cethods Subsequent to clean-
leg four runoff enencs were emnitored at each catchbasin to evaluate perforinaece itsitoring included inf lsent.
effluent. srp liquid and sunip sediment Catthbasln pollutant removals were found to nary widely, fron a sInus ten
percent (dIscharging prior swap accionajlatisns) to a posItive 90 percent. dependent on rainfall intensity and duration
On the whole. catchbasins were shown to be quite effectIve for eel ida redaction. ia the order of 60—97 percent Catch-
ba,in reemvale of associated pollutants such us chemical osygee demand (COO) and biochemical onygen deinued (BOO) were
also significant, on the order of 10-56 percent and 54-88 percent. respectively.
The second phase of wort involved the addition of an inlet strainer to each of the catchbesina as accseiplished in
European practice The inlet strainers were cooiprlsed of a meter of B mesh (0 0937 In /2 36 sin) brass screee, per-
recently amunted an an aleminic backing plate Runoff for an additional three eveets was nmeitored at each site during
this phase of worh lelet strainers were found to provIde a marginal increase in pollutant removal (up to tee percent).
In addition to that generated by the catchbasin. One interesting phensceinue was observed, ie that significant accina—
lations of dirt, leaves, grit and paper were collected daring dry weather periods between stares
ThIs work was subsisted in partial fulfillment of Grant lb R-8G4578 by Northeastern University. under joint spon-
sorship of the U S Envi ronsental Protection Agency and the Division of Water Poll stisn Control. Cssemswnal th sf
Massachusetts This report covers the period July 1978 to April 1980 and work was cosipleted April 1980
17 KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b IDENTIFIERS/OPEN ENDaD TERMS
c COSATI ricld(Group
Catchbasins, Combined sewers, Storm
sewers, Surface waters, Runoff, Water
pollution, Water quality
Catchbasin effectiveness,
Economic assessment,
Pollution abatement,
Storm runoff, Urban hy-
drol ogy
13B
18 DISTRIBUTION STATEMENT
RELEASE TO PUBLIC -
19 SECURITY CLASS (ThtsReportf
UNCLASSIFIED
21 NO CF PAGES
91
20 SECURITY CLASS (Thu page)
22 PRICE
EPA Fain, 2220—1 (Ran. 4—77) PREVIOUS EDITION Is 0050LETE
-------
DISCLAIMER
Although the Information described in this article has
been funded wholly or in part by the United States Environ-
mental Protection Agency through Grant No. R—804578 to Envir-
onméntal Design & Planning, Inc., it has not been subjected
to the Agency’s required peer and administrative review and
therefore does not necessarily reflect the views of the Agency
and no official endorsement should be inferred.
I I
-------
FOREWORD
The Environmental Protection Agency was created because
of increasing public and government concern about the dangers of
pollution to the health and welfare of the American people.
Noxious air, foul water, and spoiled land are tragic testimony to
the deterioration of our natural environment. The complexity of
that environment and the interplay between its components require
a concentrated and integrated attack on the problem.
Research and development is that necessary first step
in problem solution and It involves defining the problem,
measuring its impact, and searching for solutions. The Municipal
Environmental Research Laboratory develops new and improved
technology and systems for the prevention, treatment and
management of wastewater and solid and hazardous waste pollutant
discharges from municipal end community sources, for the
preservation and treatment of public drinking water supplies and
to minimize the adverse economic, social, health, and aesthetic
effects of p01 lution. This publication Is one of the products of
that research, a most vital communications link between the
researcher and the user community.
The deleterious effects of storm sewer discharges and
combined sewer overflows upon the nation’s waterways have become
of increasing concern In recent times. Efforts to alleviate the
problem depend in part upon the development of integrated
technologies involving non—structural best management practices
with structural storage and treatment concepts.
This report presents the summary of a field oriented
data collection effort aimed at evaluating the performance and
utli ity of catchbasins from a pollution control standpoint.
CatchbasinS were monitored during seven runoff events and
performance assessed. During three of the events specially
designed insert strainers were used to assess their efficiency.
Francis 1. Mayo, Director
Municipal Environmental
Research Laboratory
iii
-------
ABSTRACT
This report summarizes the results of a field oriented
data collection effort aimed at evaluating the performance and
utility of catchbasins from a pollution control standpoint. The
project was functionally divided into three phases, with the
first two being field data collection efforts and the last
relegated to data reduction and analysis.
In the first phase of field work, three catchbasins In
the West Roxbury section of Boston were selected from a candidate
list of over forty sites throughout the city. The catchbasns
chosen ill ustrated a diversity of land use and traffic
situatIonS, as well as design type. Each catchbesin was then
cleaned using traditional methods. Subsequent to cleaning four
runoff events were monitored during the month of December, 1979
at each catchbasln to evaluate performance. Monitoring included;
lnfluent,.efflUeflt, sump liquid and sump sediment. Catchbasln
poiiutantremoval 5weref0 uu1dt0 tY widely, from a minus 10%
(discharging prior sump accumulations) to a positive 90%. On the
whole, catchbasins were shown to be quite effective for solids
reduction, in the order of 60—97%. Catchbasin removals of
associated pollutants such as Chemical Oxygen Demand (COD) and
Biochemical Oxygen Demand (BOD) were also significant, on the
order of 10—56% and 54—88%, respectIvely.
The second phase of work involved the addition of an
inlet strainer to each of the catchbaslns as accomplished In
European practice. The inlet strainers were comprised of a number
B mesh (0.0937 i n./2.36mm) brass screen, permanently mounted on
an aluminum backing plate. Runoff for an additional three events
was monitored at each site during the month of January, 1980.
Inlet strainers were found to provide a marginal increase In
pollutant removal (up to 10%), In addition to that generated by
the catchbasln. One Interesting phenomenon was observed, In that
significant accumulations of dirt, leaves, grit and paper were
collected during dry w ather periods between storms.
This work was submItted In partial fulfillment of Grant
No. R804578 by Northeastern University, under Joint sponsorship
of the u.s. Environmental Protection Agency and the Division of
Water Pollution Control, Commonwealth of Massachusetts. This
report covers the period July 1978 to April 1980 and work was
completed April 1980.
iv
-------
I ntroduct ion
I • I Foreword
1.2 Purpose of Study
I .3 Background
1.4 Historical Review
1.5 Description of the Study/Report
Format
Concl us ions
Recommendations
Detailed Catchment Area DescrIptions
4.1 Criteria Used in the Selection of
Catchbas ins
4.2 Individual Site DescriptIons
Sample Collection and Analytical
Proced ures
5.1 Field Sampling Procedures—Liquid
Samples
5.2 Field Sampling Procedures—Solids
Samples
5.2.1
5.2.2
5.3 Other
Results of
Program
6.1 Summary of Results—Liquid Samples
6.2 Summary of Results—Sump Sediment
TABLE Q.E CONTENTS
Foreword
Abstract
List of FIgures
List of Tables
List of Abreviatlons and Symbols
Acknowledgments
Chapter I
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
ii
111
vi i
lx
x l
xli
2
4
6
8
10
11
11
12
21
21
27
27
27
30
32
32
57
Sump Sediment Samples
Inlet Strainer Samples
FIeld Determinations
the Catchbasin MonitorIng
V
-------
6.3 Summary of Results—Influent 65
Stral ners
6.4 RevIew of Catchbasin MonItoring 67
Data
Chapter 7 Analysis of Catchbasin Cleaning Costs in
City of Boston 69
7.1 Foreword 69
7.2 Boston Catchbasin Cleaning Costs 69
7.3 Catchbasln Cleaning Costs Comparison 70
7.4 Economic Analysis of Increased Catch—
basin Cleaning FrequencIes 72
References and BIbliography 78
vi
-------
LIST E FIGURES
Page
Figure I Representative catchbasln designs In the 3
United States and Canada.
FIgure 2 Locational map of West Roxbury. 13
Figure 3 LocatIonal map of catchbasin monitoring sites. 14
FIgure 4 SprIng Street catchbasln configuratIon. 15
FIgure 5 Map of Spring Street drainage area. 16
FIgure 6 Baker Street and Glenhaven Road catchbasln 18
configurations.
Figure 7 Map of Baker Street end Glenhaven Road 19
drainage areas.
FIgure 8 Photographs of Baker Street and Glenhaven 20
Road catchment areas.
Figure 9 Diagram of sampling and sample handi Ing— 22
liquid samples.
FIgure 10 Photograph of catchbasln at Spring Street 24
and pre—sump sampling at Baker Street.
Figure II Gutter and effluent grab sampling procedures. 25
Figure 12 Diagram of sampling and sampling handling— 28
solids samples.
Figure 13 Photographs of Inlet strainer unIt. 29
Figure 14 Photographs of debris collection and 31
collected debris from strainer bag.
Figure 15 Typical plots of Total Solids Influent/ 58
effluent concentrations.
Figure 16 Typical plots of TSS influent/effluent 59
concentrations.
vii
-------
Figure Ii Typical plots of COD influent/effluent 60
concentrations.
FIgure 18 Typical plots of BOD Influent/effluent 61
concentrati ons.
Figure 19 Composite plot of sediment analysis 62
for Spring Street.
Figure 20 Composite plot of sediment analysis 63
for Baker Street.
Figure 21 Composite plot of sediment analysis 64
for Glenhaven Road.
viii
-------
Tabi e
LIST QE TABLES
P ge
I
SUMMARY OF ANALYTICAL METHODS
2
SIEVE SERIES UTILIZED FOR SUMP SEDIMENT ANALYSIS
27
3
CHRONOLOGY OF CATCHBASIN MONITORING PROGRAM
33
4
CATCHBASIN MONITORING DATA — SPRING STREET 12/5/79
34
5
CATCHBASIN MONITORING DATA — BAKER STREET 12/5/79
35
6
CATCHBASIN MONITORING DATA — GLENHAVEN RD. 12/5/79
36
7
CATCHBASIN MONITORING DATA — SPRING STREET 12/7/79
37
8
CATCHBASIN MONITORING DATA —BAKER STREET 12/7/79
38
9
CATCHBASIN MONITORING DATA — 12/7/79
39
10
CATC1-IBASIN MONITORING DATA — 12/12/79
40
11
CATCHBASIN MONITORING DATA — 12/12/79
41
12
CATCHBASIN MONITORING DATA 12/12/79
42
13
CATCHBASIN MONITORING DATA 12/27/79
43
14
CATCHBASIN MONITORING DATA 12/27/79
44
15
CATCHBASIN MONITORING DATA 12/27/79
45
16
CATCHBASIM MONITORING DATA 12/28/79
46
17
CATCHBASIN MONITORING DATA 12/28/79
47
18
CATCHBASIN MONITORING DATA 12/28/79
48
19
CATCHBASIN MONITORING DATA 1/11/80
49
20
CATCHBASIN MONITORING DATA 1/11/80
50
21
CATCHBASIN MONITORING DATA 1/11/80
51
GLENHAVEN RD.
SPRING STREET
BAKER STREET
— GLENHAVEN RD.
— SPRING STREET
— BAKER STREET
— GLENHAVEN RD.
— SPRING STREET
— BAKER STREET
— GLENHAVEN RD.
— SPRING STREET
— BAKER STREET
— GLENHAVEN RD.
ix
-------
Table P ge
22 CATCHBASIN MONITORING DATA — SPRING STREET 1/14/80 52
23 CATCHBASIN MONITORING DATA — BAKER STREET 1/14/80 53
24 CATCHBASIN MONITORING DATA — GLENHAVEN RD. 1/14/80 54
25 AVERAGE FLOW RATES FOR RUNOFF EVENTS MONITORED 55
26 MASS AND PERCENT REMOVALS WITHOUT INLET STRAINERS 56
27 MASS AND PERCENT REMOVALS WITH INLET STRAINERS 56
28 MONITORING OF SUMP LEVELS IN CATCHBASINS 65
29 RESULTS OF THE INFLUENT STRAINER STUDIES 66
30 PRESENT BOSTON CATCHBPtSIN CLEANING COSTS 71
31 PERTINENT DATA — WEST ROXBURY, BOSTON TEST CASE 73
32 WWTP SOLIDS HANDLING COSTS W. ROXBURY CASE EXAMPLE 75
33 COMPARATIVE ECONOMICS OF CATCHBASIN CLEANING FREQUENCY 75
-------
ABBREVIATIONS ANQ XMBOLS
Abrev I ati on
cf cubic feet
cfs cubic feet per second
cm centimeter
cm/h centimeter per hour
fpm feet per minute
fps feet per second
ft feet
ft 2 square feet
ft 3 cubic feet
g gram
h hour
ha hectare
ID inner diameter
in/h inch per hour
lb pound
kg kilograms
km kilometer
liter
m meter
m 3 cubic meter
mg/i mu ligram per liter
ml milliliter
mm millimeter
rn/s meters per second
vs. versus
Symbols
BOD Biochemical Oxygen Demand (5 days)
COD Chemical Oxygen Demand
TKN Total KJeldahl Nitrogen
TP Total Phosphorus
TSS Total Suspended Solids
VSS Volatile Suspended Solids
WWTP Wastewater Treatment Plant
Percent
x l
-------
ACKNOWLEDGMENTS
The authors would like to commend the Environmental
Design & Planning, Inc. (EDP) staff who worked so hard to make
this program a success. This study, through its efforts
collected the first simultaneous performance data on catchbaslns.
We would like to particularly express appreciation to
the members of the EDP field crew, including David Walsh, Stephen
Becrgstrom and Robert SilverIo for their many hours of inclement
weather endured.
Final ly, last but certainly not least, we would I Ike to
express our sincerest appreciation to Nora W. Scanlan and Nickle
Kronenberg for their patience in typing this report.
Northeastern University (NU)was the recipient of the
combined grants from the U.S. Environmental Protection Agency and
the Division of Water Pollution Control, State of Massachusetts.
Drs. Frederic C. Blanc, James C. O’Shaughnessy and Professor
Richard J. Scranton were the project officers for Northeastern
University. Environmental Design & Pianning, Inc. was the major
engineering subcontractor to NU for the project. Mr. Gerald
Aronson, Executive Vice President, EDP, was the project manager.
Mr. David Watson, EDP’s Supervisor of Field Services supervised
all the field work. Mr. David Kippenberger, EDP’s Supervisor of
Technical Services supervised fabrication of the inlet strainers
and special sampling equipment used In this program. Dr. William
C. Pisano, President, EDP, was the principal investigator for
this project and provided aid in report preparation. The final
report was prepared by EDP, mc.
PROJECT OFFICERS/SPONSORS
Richard Field, Chief
Robert Turkeltaub, Staff Engineer
Storm and Combined Sewer Section
Wastewater Research Division
Municipal Environmental
Research Laboratory
U.S. Environmental Protection
Agency
Charles Button, Chief Engineer
Boston Water & Sewer Commission
Boston, Massachusetts
Thomas McMahon, Director
Water Resources Commission
Massachusetts Division of
Water Pollution Control
Westboro, Massachusetts
Northeastern University
Department of Civil Engr.
Boston, Massachusetts
xii
-------
#APTER 1
INTRODIJCT ION
1 • I Foreword
The purpose of this study is outlined In Section 1.2.
Background materials describing catchbasin functions and American
and European design and maintenance practices are given in
Section 1.3. An historical review of literature dealing with the
pollution control aspects of catchbasins is given in Section 1.4.
Section 1.5 contains a description of the study and report
format.
1 .2 Pijreose j _____
Control of stormwater runoff is a problem of increasing
importance in the field of water quality management. Over the past
70 years, there has been extensive use of catchbasins for coarse
material removal from stormwater runoff, yet catchbasin pollutant
removal effectiveness has not been evaluated in depth.
In a recent study entitled “Catchbasin Technology
Overview and Assessment,”(l) it was recommended that monitoring
programs should be undertaken to: 1) determine the impact of best
management practices in reducing sol ids and other pollutant loads
in surface runoff that must be collected from urban areas and,
introduced to the sewer through catchbasins; 2) evaluate the
effectiveness of closely monitored catchbasin cleaning programs
with respect to impacts of cleaning frequency and, techniques on
solids carryover as well as general pollution abatement and; 3)
determine the extent to which sol ids deposition can be mitigated
by properly designed and functioning catchbasins.
These recommendations were based on an analysis of
catchbasifl pollutant removal performance using secondary data
synthesized from a variety of sources. Direct and concurrent
measurement of influent and effluent pollutant characteristics
had not been previously performed. Prior measurements Included
either street surface pollutant characteristics or spot grab
sampling of catchbasifl sump volumes.
The basic thrust of the research was to careful ly
monitor simultaneous Influent and effluent characteristics for
several catchbasinS in the Boston Metropol itan area. The primary
emphasis of this study focused on the characterlzaton of the
pollution load attenuation characteristics of a catchbasin. A
secondary goal examined the pollutan$ reduction effectiveness of
insert strainers In several catchbeslns within the study area.
1
-------
These dev.iceS are commonly used in European practice and have
been shown effective for removing gross floatables and settleable
solids, such as cigarette butts, eaves, lawn clippings and
pa per.
1 .3 kçr iind
!A catchbasin is defined as a chamber or well, usually
built at the curbline of a street, for the admission of surface
water to a sewer or subdra ln, having at its base a sediment sump
designed to retain grit and detritus below the point of overflow.
Because some communities call any device that receives stormwater
a catchbasifl, the distinction is made between those devices that
intentionally trap sediment and those that do not. In this
report, the device that traps sediment Is what is referred to as
a catchbasln.
Stormwater runoff In urban areas normally fiows for a
short period of time in the gutter and is diverted by an inlet
structure. leading to an underground conduit or open channel for
transportation to a receiving body of water. The underground
conduit, either a storm or combined sewer, may be protected from
clogging by catchbasins built in conjunction with the inlets.
Catchbasins serve two main purposes: to prevent sewer
gases from escaping through the inlet gratings and; to prevent
heavy or large solid matter from the street from entering the
sewers. The trapping of sewer gases is accomplished by a water
seal. The retention of soi Ids is achieved by providing a sump or
settling basin in which the heavy solids settle to the bottom,
w hi I e the light sol I ds float on top. Water drai ns to the sewers
through the outlet of the catchbasin which is generally a few
Inches below the water surface. These basins are normally built
under the inlet gratings or opnings, either under the gutter or
just back of the curb. Occas,onally, one catchbasin will serve
two or more standard inlets.
In American practice, a standard catchbasin appears to
be nonexistent (I). Attempts at uniformity within individual
cities (Figure 1) show varying degrees of success. The
effectiveness of the water seal gas trap is an Important issue in
American practice, since it is directly proportional to the
antecedent dry period and the corresponding evaporation rate, in
addition, organics in the catchbasifl if allowed to accumulate,
may decompose with time and contribute odors similar to sewer gas
even if the water seal has not evaporated.
In Europe catchbasin sizes vary, except in Germany
where they have been standardized. Two types of catchbasins are
used: a simple depositary type and another type generally called
2
-------
2 It — 0 Ii.
ATLANTA TORONTO
Figure 1. Representative catchbasin designs in the United States and Canada.
Source: Mstcalf & Eddy, Inc. (1)
0
“4
z
C
0
NEW YORK
SAN FRANCISCO
3
-------
a “selective” catchbasin In which a bucket sieve or some other
means is used to select and separate various solid materials. The
latter type varies greatly in different countries and various
cities. The buckets provide an easy and rapid method for cleaning
by street crews. As part of this effort, Inlet strainers were
fabricated and installed in the monitored catchbasins to assess
their pollutant removal effectiveness, thus simulating the
European practice.
European catchbaslns tend to be small r in size,
reflecting closer spacing, i.e., smaller drainage areas per unit.
Most European cities are located on relatively flat terrain with
long—duration, low—intensIty, high—frequency rain patterns and
most catchbasins do not include gas traps because of the frequent
flushing by storm runoff. Catchbaslns are usually circular in
shape. A perforated removable bucket is used to catch large
objects, and the runoff flow Is rel led on to carry the smaller
material on into the sewer.
There is a definite tendency in most of the textbooks
in Europe to discount, or not recommend, depository type
catchbasins, because the material that accumulates with the water
is subject to fermentation odors and other problems of
stagnation. When depositary type basins are requlred, a siphon
modification, in which a separation baffle is Installed, Is often
used. The solid material is left in one compartment and the flow
Is basically drained through the siphon and underneath the
baf f I e.
1.4 HIstorical Review
Historically, the purpose of catchbasins is to prevent
sewer clogging by trapping coarse debris and to prevent odor
emanations from the sewers by providIng a water seal. The
prevention of sewer clogging was especially Important prior to
the existence of good quality street pavements. In areas where
streets were partially or wholly unpaved, significant quantities
of stone, sand, manure and other materials were washed into the
sewer system during periods of rainfall. Al so, during the earl ier
years of sewer construction, lIttle attempt was made to maintain
self—cleaning velocIties In sewers of at least .61m/s (2 fps)
(2).
The u5efulness of catchbaslns was considered marginal as far
back as 1900 (3). Most modern texts generally agree and only
provide short disclaimers regarding the value of catchbasins,
except where deposition of large amounts of grit Is expected In
the sewer without them (4,5). Despite the purported reduced need
for catchbaslns, they are stilt used widely In many parts of the
country (6).
4
-------
Little investigation has been conducted on the
hydraulic characteristics of flow within a catchbasin. The
University of ill Inols conducted some investigations and
concluded that catchbaslns are hydraulically inefficIent (7). In
another study of hydraulic characteristics by the APWA, it was
found that for all practical purposes complete mixing occurs
within a catchbasin (8). This seems to fit In with the University
of Illinois’ studies which indicated that a catchbasin is a poor
sedimentation device because of its tendency to re5uspend the
solids in the sludge deposits even at moderate inflow rates.
Attempts by the University of Illinois group to improve
settling by baffling, showed additional adverse effects. However,
a more recent study of catchbasins with large antecedent debris
contents indicated that only about one percent of the antecedent
content washed out (9). it was concluded, however, that the
material flushed out as the initial slug would have a substantial
p01 lutlonal impact on the receiving waters. In the APWA study, It
was also concluded that catchbasins may be one of the most
important singie sources of pollution from storrnwater flows (8).
All of the studies concluded that catchbasins cannot efficientiy
satisfy the competing objectives of good hydraulic
characteristics and solids retention.
Pertinent conclusions relating to catchbasln pollutant
removal effectiveness from a recent assessment study (1) are
excerpted as follows:
1. Existing catchbasins exhibit mixed performance with
re5pect to pollution control. The trapped liquid purged from
catchbaslns to the sewers during each storm generally has a high
poll ution content that contributes to the intensification of
first—flush loadings. Countering this negative impact Is the
removal of poll utants associated with the solids retained in, and
subsequently cleaned from, the b&sin.
2. The collection of conclusive field data is hindered
by the prevailing poor conditions found in most basins resulting
from under financed and poorly monitored cleaning programs.
3. Approximately 95 to 98% of the BOD load in the
liquid contained in a catchbasin prior to a storm will be
displaced to the sewer by a rainfall of as little as 0.05cm/h
(0.02 ln./h) lasting four hours. As a side note, the displacement
of catchbasin surnp volume is also dependent on the size of the
tributary area as well as the rainfall intensities. This is
approximately equivalent to the waste discharged by one person in
one day. -.
5
-------
4. On an annual basis, the amount of material that
would be retained in a catchbasin is given in the foliowing
tabulation:
Percentage j Mater ia -i Retained J.j
Ce-tchbasln jg Individual Storm
Range 1 Material Retained ( Percentage)
High
Total soiids 42.1 75.0
Vo latilesoiids 15.2 25.5
BOD5 15.5 25.6
COD 7.5 14.1
KJeldahI nitrogen 14.6 27.4
Nitrates 9.5 17.1
Phosphates 2.3 6.0
Total heavy metals 37.4 64.4
Total pesticides 13.6 29.7
5. From a pollution abatement standpoint, the benefits
of catchbasins appear limited. For example, the net removal of
BOD from a well—designed and maintained system of catchbaslns
based on conformance to observed data, is expected to be in the
range of five to 10% of the applied load. ,A potential exception
may be the removal of heavy metals which, as tabulated above,
could be significant.
M.I j these conclusions reached ir ni desk—top
1 L .i i Qm x i i i.e., cel-chbasin sump
information from San Francisco and nationai assessments of street
load solids characteristics. These results e.r tentative e.n4
± uiti. . JLtLn. j Ln.g Lr..Q ± .p cIm c. mr Qm n.i.
from programs such as those conducted In this study.”
1.5 DescriDtion j jh. Study/Report Format
This report details a field monitoring effort aimed at
assessing the pollutant removal effectiveness of catchbasins. As
mentioned in the prior sections, aithough catchbasins have been
in use for roughly 70 years little actual monitoring of
performance has been conducted and no studies have collected both
influent and effluent data simultaneously. During the period of
November 1979 through January of 1980 a total of seven runoff
events were monitored at three separate catchbasin sites,
yielding a total of 21 runoff events monitored. All of the catch—
basins were located in the West Roxbury section of the city of
Boston. Anaiyses were conducted for Total Suspended Solids (TSS),
Volatile Suspended Solids (VSS), Chem ical Oxygen Demand (COD),
6
-------
Biochemical Oxygen Demand (5 days) (BOD), Total KJeldahl Nitrogen
(TKN), Total Phosphorus (TP), sediment particle sizing and,
percent volatile. Special analyses were conducted to assess the
sump liquid and solids conditions prior to and subsequent to the
runoff events. Inlet strainers similar to those used In Europe
were specially fabricated, Installed and monitored over three
runoff events to assess their impact on overall performances.
Site selection and details of the various catchbaslns
monitored are described in Chapter 4. Sample collection and
analytical procedures are described in Chapter 5 and finally,
monitoring results are shown in Chapter 6. Estimates of
catchbasin cleaning costs In the City of Boston are presented in
Chapter 7 and compared with national average results.
7
-------
CHAPTER 2
CONCLUSIONS
The conclusions of this investigation are as follows:
1. Catchbasins were very effective in removing suspended solids—
related pollutants from influent waste streams. Pollution mass reductions
of 60 to 97 percent suspended solids, 48 to 97 percent VSS for relatively
low intensity storms during December and January, 10 to 56 percent COD, and
54 to 88 percent BOD were observed. No data were obtained for summer type
storms.
2. The limited data collected indicated that catchbasins do little
with respect to nutrient removal.
3. Though the total mass of the influent to the catchbasins varied
widely, the concentration profiles of both the influent and effluent with
time were very consistent.
4. Sieve analyses of catchbasin sump sediment samplings (taken 21
times over the course of the evaluation program) yielded results consis-
tent with those found in the literature.
5. Sump sediment was highly organic-—on the order of 60 to 90
percent, depending on particle size range.
6. Inlet strainers were designed, fabricated, and installed on the
three test catchbasins for three runoff events each. The strainers
consistently retained significant dry weather accumulations ranging from
150 to 500 g of dry solids per day.
7. Accumulation of dry weather solids in the catchbasin inlet
strainers seemed to be primarily a function of degree of vehicular traffic
at each location.
8. Inlet strainers offered a slight gain in overall pollutant
removal efficiency of catchbasins, but they would not be functional on a
large scale. These devices are effective for the removal of course
8
-------
material that could cause visual upsets. Problems with clogging and
potential for decomposition and ultimate discharge of pollutants negated
their value unless weekly (or more frequent) maintenance was employed.
9
-------
CHAPTER 3
RECOMMEN DAT IONS
The following are recommendations generated from this
study.
I. Catchbasins, if maintained, are an efficient
pollutant reduction/maintenance tool and should continue to be
utilized.
2. Similar monitoring studies such as conducted in
this study should be conducted in other geographic areas to
substantiate the findings of this study. Regions recommended are
the midwest, south and west because of their differences in
climate, hydrology and system characteristics.
3. Since energy dissipation is of prime importance
to the function of catchbasins, further research should be
conducted into simplistic ways of reducing infiuent energy.
4. FIeld scale demonstration of closely monitored
concurrent street sweeping, catchbasin cleaning and sewer
maintenance programs should be conducted in varying terrain for
both separate and combined sewerage systems to investigate the
optimal mix of best management practices from maintenance and
pollution control viewpoints. The main emphasis of the studies
should be devoted to carefully monitoring the separate and Joint
effectiveness of these techniques and conclude with an assessment
of the impacts of cleaning frequency and mechanisms of sol ids
carryover, general poliutlon abatement and associated costs.
5. Additional monitoring studies should investigate
the effectiveness of catchbasins for removal of heavy metals as
well as oil and grease poll utant removals.
-------
CHAPTER 4
DETAILED CATCHNENT AREA DESCRIPTIONS
4.1 Criter1 a Used in ±J Seleclion j Catctibaslfls
Although, it would logically seem that site selection
for a catchbasin monitoring program would be a simple matter,
that was not the case. Prior to inspection of possible candidate
sites an exhaustive review of detailed sewer maps for
approximately 3000 acres of the City of Boston was conducted.
This review of mapping information provided a pre—screen for
candidate sites. Criteria utilized in the pre—screen were as
follows: 1) All catchbasins to be monitored had to be indicated
to discharge directly to a receiving manhole and not into the
sewer line; 2) The catchbasln had to have a readily definable
fixed tributary area and; 3) Traffic patterns and land use
density had to vary. Unfortunately, it seems that most catch—
basins in Boston are connected directly to the adjacent receiving
sewer without access formed by a manhole. For the purposes of
this study, it was deemed that access to the catchbasin discharge
via a manhole connection would be most desirable for the purpose
of monitoring. The catchbasin effluent sampling would be
conducted at the discharge of the catchbasin to the receiving
sewer in a manhoie. As a result of this criteria, of the
literally thousands of catchbas Ins within the area, a list of
approximately 50 candidates were generated from the mapping
review. This list was reduced to 40 potentIal sites on the basis
of the other two criteria.
Approximately 40 catchbasins in the metropolitan area
were field inspected prior to choosing the three whose
performance was to be evaluated during this study. The three
specific criteria used In the final selection are described below
in the order of importance.
Of foremost value to the study was the selection of at
least two different catchbesin design configurations. The second
priority was to assure that all catchbasfn catchment areas were
of varying tributary acreage and more importantly, showed
differences of automobile traffic density and surrounding land
use. Thirdly, the physical dimensions of the catchbasin and the
receiving manhole were reviewed to ensure proper space and access
required for sampling equipment. The most important requirement
of the monitoring manhole was adequate height between the outlet
and the sewer free water surface to permit placement of a
specially constructed sampling device. The receiving manhole also
had to be large enough to house two sampling devices (influent
11
-------
and effluent) and a discharge flow monitor. After careful review
of the approximately 40 catchbasins, three test sites were chosen
in the West Roxbury section of Boston.
4.2 IndivIdual Si±eDes riptioitS
The West Roxbury section of Boston is depicted In
Figure 2 and may be typified as moderate income residential, with
mixed commercial occurring primarily along several main road
tracts. General housing density in the area Is moderate, with
lawns and streets in generally good condition. The sewer system
In this area Is entirely separated (as constructed), with the
exception of a few streets. The approximate median age of the
housing in the area is 40 years. Drainage from the area
discharges rprimarlly into the Upper Charles River through an
extensive drainage system. Topography in the area varies from
moderately hilly to flat.
The three catchbaslns selected for the study, which are
shown in Figure 3, are located on the corners of Spring and
Alaric Streets, Baker Street and Joyce Kilmer Road and Glenhaven
Road and Keystone Street. Ee.ch site area is described In detail
below.
The catchbasln at Spring and AlarIc Streets Is of a
different configuration than the other basins selected. Whereas
the other two catchbaslns selected are comprised of single sumps,
this design utilized a double surnp arrangement. Figure 4 Is a
diagram of the catchbasin. Gutter flow Is initially coi lected by
a shallow b sln with a non—trapped outlet pipe, eight inches in
diameter, discharging the flow into a oval shaped settling basin
approximately three feet by four feet In plan and 3 1/2 feet
deep.ThesumpundertheCurb measures24 inchessquarewith six
inches of depth beneath the discharge inlet. The grates covering
all the selected catchbasins are square with lengthwise silts
averaging two inches In width.
The area tributary to the Spring Street site Is shown
in Figure 5 and equals approximately 3.42 acres. The area along
Spring Street is characterized by eight old large single family
houses and a mechanic’s garage. Open space comprises about 30% of
the catchment area along Spring Street. The drainage area along
Alaric Street and Alaric Terrace represents about 27% of the
total catchment area. The street slope is about 20%. Traffic on
Alaric street Is light and services a very srnal I residential
area. Conversely, Spring Street is a major commercial four—lane
traffic route with parking on both sides of the street. The area
is generally littered with paper and other debris and exhibited
high rates of grit accumulation over short periods of time.
12
-------
.1
(
Figure 2. Locational map of West Roxbury.
13
-------
Figure 3. Locational map of catchbasin
monitoring sites.
meters
LEGEND
• Monitoring site
o Catchbasin
Scale
o ioo 200 300
feet 400 800
4
N
14
-------
TOP VIEW
48
Figure 4. Spring Street catchbasin configuration.
PROFILE
STREET
A
Slope Unlwown
To
SEWER
48’ ‘ li -I
T
T
CURB
15
-------
Figure 5. Map of Spring Street draitiage area.
TEST CATCHBASJN
DRAINAGE AREA
BOUNDARY
C,
)Q.
—
SCALE
meters I I
O 10 20 30
feet — —
0 40 80
16
-------
The catchbasin design of the sites on Baker Street and
on Gienhaven Road (Figure 6) are very similar and conform to the
typical configuration referred to as the SAN FRANCISCO style. The
only difference between the basins other than capacity, is how
gutter runoff enters the sumps. The Baker Street site has a brick
table constructed one foot below the street grating. Runoff then
drops from this table to the water surface, approximately two
feet below. The sump is oval shaped (four feet by 4—1/2 feet) and
drops 3 feet below the invert of the outlet pipe. The outlet pipe
diameter Is eight inches.
This site is the smallest area In tributary acreage as
shown in Figure’ 7.Vehicular traffic Is moderate in comparison to
observed traffic along Spring Street. Total catchment area size
is approximately 1.56 acre. Flow to the catchbasln comes from
only one direction, on Baker Street. The street Is a two—laned,
medium—traveled secondary road. It Is without curbstones for 75%
of its length; however, the pavement over this area is continuous
to the sidewalk. General condition of the pavement is very good.
The Baker Street cetchment area’s land use is shown in
Figure 8 and is characterized by eleven small single family
dwellings with lawn areas averaging 300 square feet and single
car paved driveways. Few trees and bushes grow near the roadside.
On—street parking is exhibited to a relatlveiy high degree due to
two factors. First, many households own two automobiles, but have
driveway space for only one. Second, a pre—elementary school Is
located on the opposite side of the street, responsible for
increasing daily children delivery and pickup parking. School bus
traffic to the school comprises the only heavy vehicle traffic on
Baker Street. Overall street appearance is always very clean.
The catchbasln at the Glenheven Road location is of the
SAN FRANCISCO type catchbasin design. The sump is located
directly below the street grating, with a five—foot drop from the
street to the water surface. The capacity of this sump is greater
than the other two catchbosins, measuring 5—1/2 feet in diameter
and dropping five feet below the eight—inch outlet pipe invert.
Flow to the catchbasin comes from both ends of Gienhaven Road,
yielding a total tributary area of 1.21 acre. Glenhaven Road is
located within a residential area with only iight vehicular
traffic. Vehicular traffic is slight In comparison to observed
traffic along Spring Street. The entire area is curbed and has
paved sidewalks. Many large older trees line both sides of the
street, yielding a very high leaf and twig concentration in the
catchbasin sediment. Street pavement is in good repair.
17
-------
To
SEWER
54”
BAKER STREET
To
SEWER
48”
PROFILE
TOP VIEW
CURB
K “
PROFiLE GLENHAVEN ROAD TOP VIEW
Figure 6. Baker Street and Glenhaven Road catchbasin configurations.
18
-------
Figure 7. Map of Baker Street and
Glenhaven Road drainage areas.
4
N
meters i I
0 10 20 .30
feet — — —
o 40 80
Iw j
I-jo
I
‘U
I)-
I 0-i
L
C ..
T ST C ATC H BASIN
DRAINAGE AREA
BOUNDARY
SCALE
-------
Baker Street catch ent area Glenbaven Road catcluient area
Figure 8. Photographs of Baker Street and Clenhaven Road eatchment areas.
1%)
-I
-o
-------
CHAPTER 5
SAMPLE COLLECTION AND ANALYTICAL PROCEDURES
l-ntrod ucl Ion
Successful monitoring of catchbasin performance
required sampling from several waste streams containing
relatively high amounts of grit and floatable material. In order
not to bias the catchbasin performance results, a series of
special devices were fabricated to allow for representative
sampling of the various waste streams. This chapter outlines the
various sample types and procedures used in the field, as well as
analytical procedures utilized in the laboratory.
5.1 Field pling Proce ures—Liqu-id mples
The catchbasin monitoring program was designed to
collect representative and simultaneous influent and effluent
samples, to assess true pollutant removal performance. As
mentioned in Chapter 4, considerable effort was expended in
selecting catchbasins suitable for monitoring. Prior to the
initiation of the sampling program, each catchbasin was cleaned
by the Boston Water and Sewer Commission cleaning crews, using
typical clamshell bucket equipment. No attempt was made to
further clean the catchbasins beyond that accomplished by the
clamshell bucket, since the purpose of this study was to assess
the effectiveness of catchbasins on a” real I Ife” basis.
Clamshell bucket cleaning equipment is the most predominate type
used in the United States for catchbasin cleaning and although
convenient, is not totally effective. Subsequent to cleaning,
each catchbasin had at least 12 inches of residual materials on
the bottom and substantial accumuiations stuck to the sidewalls
of the sump. Undoubtedly, the remaining residuals effected the
overall catchbasin performance.
Figure 9 depicts the sampling and analytical procedures
used for the various liquid samples taken. As may be noted from
the figure, samples taken included: sump grab sample prior to
runoff event (pre—sump sample); gutter or influent samples at the
inlet to the catchbasin during storm event; effluent samples taken
at the outlet to the receiving sewer manhole during storm event
and finally, samples taken in the sump subsequent to the runoff
event (post—sump sample). Sampling of the various liquid sample
types were conducted for al I runoff events at the three
catchbasins monitored.
21
-------
I.
Pre Sump Sample
TSS
I
vsS
1 liter
Sample
COD
BOD
TKN*
TP*
- Influent Sample
— I
Effluent Sample
Two Samples 1—2 Gallon Sample
350 ml 1 Liter
TSS COD
I BOO
TKN* I
VSS TP* I
TSS
vSS
Post Sump Sample
1 Liter Sample
Poured back
& forth 3x
100 m l -
Sample
I
COD
BOD
TKN*
TP*
-
S Shaken
lOOmi
TSS
I
VSS
I
COD
BOD
TKN*
TP*
*Selected Samples
F
I
Figure 9. Diagram of sampling and sample handling—liquid samples.
-------
Initially, the primary thrust of the catchbasin
monitoring program was to be conducted by automated sampling and
flow gaging equipment. Since both the influent and effluent
samples would have significant fractions of grit and sin_ce
commercial sampling equipment will not adequately capture grit,
special sampling equipment had to be designed. The special
sampling equipment was in essence, a mechanical grab sampler.
Monitoring of the influent utilized a specially constructed
mechanical scoop to take gutter samples and discharge them
directly into the appropriate sample bottle in a sample bottle
cassette. Effluent samples were collected by passing a sampling
scoop through the free effluent discharge Into the receiving
sewer manhole, collecting a complete “slice” of the discharge
volume and discharging the collected fraction into a sample
bottle In a sample bottle cassette.’
During the sampling program both automated end manual
techniques were employed. Since EDP field crews were able to be
onsite during most of the runoff events, grab sampling techniques
were used for those events. The grab sampling procedures
employed are shown in Figures 10 and Ii.
Figure 10 shows the pre—sump sampling procedure. A
specially designed sample bottle holding device was constructed
for this purpose to allow obtaining cross sectional sump
samples. lnitlaliy, a sample bottle was loaded in the device and
the trigger released, tightly sealing the bottle closed. The
bottle was then lowered in the surnp to the appropriate depth(s)
and the trigger mechanism pulled, allowing the bottle to fill.
At any time, release of the trigger mechanism would close off the
sample bottle, allowing movement to another position for cross—
sectional sampling. The post—sump sample was taken In a similar
manner as the pre—sump sample (within two to five minutes of
cessation of runoff).
Grab sampling of the gutter influent and catchbasln
effluent flow is shown in Figure II. Grab sampling of the gutter
was accomplished by collecting a cross section of the flowing
gutter materials and depositing the contents into a sampie
bottle. in all cases the gutter area where samples were taken
was maintained clean prior to runoff events, to ensure no
sampling bias. Influent grabs were taken via a series of
scooplngs deposited into two bottles, as shown in Figure 9. Due
to the great difficulty in obtaining a thoroughly mixed 100 ml
fraction of a one liter sample, a single 350 ml sample was used
for the suspended solids determination. The second sample was
used for the determination of all other parameters.
* it should be pointed out that even this method of sampling
would not account for the slower movement of the particulate
(Foot note continued on top of page 26)
23
-------
F ’.)
Catchbasin at Spring Street
Figure 10. Photograph of catchbasin at
Technician taking pre—suinp sample at
Baker Street
Spring Street and pre—sump sampling at Baker Street.
-------
Collection of gutter grab samples
Figure 11. Cutter and effluent grab sampling procedure.
Collection of full volume effluent samples
C )’
-4
rn
-------
*flowfleld compared to the liquid flowfield and samples are only
taken for an instantaneous period of time as opposed to
throughout the entire influent — effluent period. These
deficiencies disallow totally representative sample collection.
Effluent grab sampling and flow monitoring was
accomplished by suspending a sampling pall beneath the discharge
of the catchbasln to the receiving sewer manhole for a timed
period. In this manner, both flow and quality were determined
simultaneously. The total volume sampled was returned to the
laboratory for analysis. The total volume collected and measured
per sampling interval was divided by the collection time to yield
flow rate. The collected effluent sample, in the order of one to
three gallons, was then mixed by pouring from one pail to another
three times. During the final pouring, an approximately 100 ml
sample was decanted rapidly into a graduated cylinder for the
suspended solids determination. All other parameters analyzed
for were determined from samples drawn from the large pail.
Table I presents a summary of the analytIcal procedures
used during the cetchbasin monitoring program. Replicate analyses
were performed every sixth to eighth sample for all collected
sets.
TABLE I
JMM R 3 1 ’ f AN Y1-ICiM ME-THOOS
Parerneter na -1 t1 ta-i Netfrods
Suspended Solids Total Residue Dried at l03—105c
S.M. 208A*
Volatile Suspended Solids Total Volatile and Fixed Residue
at 550c S.M. 208E
Total 1 Jeldahl Nitrogen Nitrogen (Organic) S.M. 42i
BOD Oxygen Demand (Biochemical)
S.M. 507
Total Phosphate Preliminary Digestion for T.P.
S.M. 425c
Stannous Chloride Method
S.M. 425E
COD Oxygen Demand (Chem.)”
Ampule COD Method
26
-------
* (10) Standard Methods for the Examination of Water and
Wastewater 14th EditIon, 1975 APHA—AWWA—WPCF.
** (II) OCEANOGRAPHY INTERNATIONAL CORP. E.P.A. approved
Alternative Method Federal Register Vol. 43, No. 45, Tues., March
7, 1978.
5.2 F1e{d o11i ’ç ff ere So1+ds S rio-Ie-s
5.2. I uinp Sedlineirt amo1es
Prior to each runoff event the level of sediment in the
catchbasin sump was measured and then sampled. Samples were
taken by means of a cross sectional scooping as depicted in
Figure 12, to assure a representative sample. Each sediment
sample so collected was then air dried, weighed and then a sieve
analysis conducted. The sieve series employed was the following:
TABLE 2
S1€ fE SE -IES 1 [ 1 E R StJt’W S€D-IMEWT At4ALYSIS
Stai dard leve thnnber Size Opening
- In 1 es
8 0.0937 2.36
6 0.0469 1.18
30 0.0234 0.600
50 0.0117 0.300
100 0.0059 0.150
200 0.0029 0.075
Pan
Subsequent to the sieve analysis, each sieved fraction was fired
to conduct a percent volatile analysis. All procedures followed
the prior referenced Standard Methods”.
5.2.2 - lwIet Sti-elfler Satne-les
Inlet strainers were fabricated and installed to
assess their additional pollutant removal benefit on catchbasins.
A typical inlet strainer is shown on Figure 13. The inlet
strainers were constructed of United States standard number 8
mesh brass screening (0.0937 in., 2.36 mm), attached to an
aluminum plate. Samples from the first four runoff events were
collected without the use of inlet strainers. Subsequently,
samples from three additional events were monitored using the
inlet strainers. Two types of samples were collected from the
strainers; I) accumulations occurring during the dry period
between sampled events and 2) accumulatIons generated during
the runoff events.
27
-------
Sump Sediment
Inlet Strainer Samples
Cr088 Sectional
Scoop Sample
+
Air Dry
+
Sieve Analysis
+
Firing of each
Sieve Fraction
Figure 12. Diagram of sampling and sample handling—solids samples.
Entire Contents
put Into bucket
I
Air Dry
Weigh Total Contents
+
Sample Splitting
+
Weigh
+
Firing of Representative
Sample
N)
OD
Runoff Samples
I
-------
Strainer bag insert
Figure 13. Photographs
of inlet strainer unit.
‘ .0
I
Typical dry weather collected debris
-------
The field procedure was such that the Inlet strainer
was left in place between events. Prior to an impending event,
the Inlet strainer would be removed from the catchbasin and all
contents put into a collection pail for transport to the
laboratory. The inlet strainer would then be reinstalled Into
the catchbaslfl for collection during the event Itself.
Subsequent to the runoff event, the Inlet strainer would again be
removed and all contents put Into a separate collection container
for subsequent analysis. All samples so collected were then air
dried, weighed and a representative fraction fired (same
procedure as VSS analysis), to ascertain total mass collected and
percent volatile. Figure 14 Is a photograph of debris collection
in an Inlet strainer and collected debris in the laboratory.
5.3 O-tlier f -I el d De-terml ira H n s
Monitoring of precipitation during a runoff event was
conducted using an automated recording rain gage located adjacent
to the site. Additional depth and velocity measurements were
taken in the gutter during runoff events to provide additional
flow data.
30
-------
Dry Weather debris collected
Glenhaven 8.oad Baker Street
Spring Street
rn
-u
CA )
Wet weather debris collection
Figure 14. Photographs of debris collection and collected debris from strainer bag.
-------
CHAPTER 6
RESULTS QE fli.E CA-TCHBASIN MONITORING PROGRAM
I ntr duct Ion
A total of seven runoff events were monitored during
the period of December 5, 1979 — January 4, 1980. The first
four events were monitored without inlet strainers and, the last
three with them in place. The following Chapter presents a
summary of results of the catchbasin monitoring program. Section
6.1 presents a summary of results for all stations including
chronology, sump sampling data and all water qual ity data
collected. Section 6.2 presents the results of the sump sediment
testing program. lnfluent strainer results are presented in
Section 6.3 and finally Section 6.4 presents a review of
findings.
6.1 Summary j Results—Liquid Samo-ies
A chronology of the catchbasin monitoring program is
shown in Table 3. As may be noted from the table, the total
program extended from December 5, 1979 through January 29, 1980.
During that period a total of nine runoff events occurred, of
which seven were sampled, plus one minor snow melt occurring
December 14—16. Tables 4—24 present all water quality data
generated during the catchbasln monitoring program. Average flow
rates for each of the measured runoff events are shown in Table
25. Two points of Interest may be generated from the table; I)
the average flows measured tended to be somewhat lower than
expected and 2) runoff to each catchbasin was proportional to
catchment area. The first point of interest is most important In
assessing the data presented in this chapter. Given the
tributary areas and probability of various intensity events in
the Boston area, runoff to the catchbasins in the order of 0.01—
0.12 cfs would be expected. All of the average flows measured
were In the range of 0.013 — 0.05 cfs. Average runoff correlated
reasonably with average rainfall. Lower flow rates would
naturally yield less turbulence in the catchbaslfl and, ideally
correspondingly higher removals.
Table 26 Is a summary of the total computed mass and
pollutant removals measured during the first four runoff events
at each location. These data represent events without the use of
inlet strainers. As may be noted from the data In the table,
very high removals of solids ranging from 60—97% were evidenced.
Correspondingly high removals were observed for VSS (48—97%), COO
(10—56%) and BOD (54—88%). Although some negative removals were
observed for all parameters except VSS, the overall solids
32
-------
TABLE 3. CHRONOLOGY OF CATQIBASIN MONITORING PROGRAM
Date
12/5/79 Runoff event monitored Moderate intensity/short duration
(Average Intensity = 0.09 in./h)
12/7/79 U I I U II
(Average intensity 0.06 th./h)
12/12/79 “ II It It It I I
(Average intensity — 0.08 in./h)
12/14/79 Snow Approximately one inch
12/14/79 Snow Melt
12/25/79 Runoff event Nighttime precipitation 0.33 in.
cyclic periods of high intensity long
.durat ion
12/27/79 Runoff event monitored Rain gage inoperative
12/28/79 Insert strainers instal—CAverage intensity 0.11 in./h)
led/runoff event
monitored
11 11/79 Runoff event monitored Late night storm high ntensity
Insert strainers 0.49 inch rain — short duration
installed (rain gage inoperative)
1/14/80 Runoff event monitored (Average intensity = 0.09 in./h)
Insert strainers
installed
1/29/80 Insert strainers removed
33
-------
TABLE 4. CATCItBASIN MONITORING DATA I
LOCATION SPRING STREET I
EVENT DATE 12/5/79 I
_I
ISAMPLE SAMPLING SOD COD TSS VSS TKN TP I
TYPE TIME* I
(minuteB) mg/I mg/I mg/I mg/i mg/i mg/i I
I I
IINFLUENT 0.0 — 730 10167.2 1382.2 5.0 0.48 I
I 0.5 132 665 4396.4 498.3 — 0.56 I
I 1.0 72 370 2085.7 170.8 5.6 0.32 I
I 1.5 52 235 1805.4 167.8 — 0 .18 I
I 2.0 42 185 1320.0 130.9 — 0.17 I
I 2.5 27 210 1426.9 145.8 5.0 0.24 I
I 9.0 11 45 798.2 57.1 2.1 0.08 I
I 16.0 12 60 303.5 25.2 — 0.10 I
I 17.0 17 55 267.8 27.7 — 0.05 I
I 18.0 12 25 491.4 57.7 — 0.09 I
I 19.0 — 10 465.9 63.7 — — I
IEFFLUENT 16.0 122 235 1097.7 241.1 7.4 0.37
I 17.0 112 130 1168.6 265.9 — 0.30 I
I 18.0 — 180 578.1 87.7 — 0.24 I
I 19.0 75 95 659.0 143.2 6.0 0.24 I
I 20.0 57 155 369.2 51.7 — 0.17
21.0 62 130 606.4 55.1 — 0.18
IPRE—SUMP — 130 1097.7 241.1 — 0.12
IPOST-SUMP — - — — — —
* Time since start of storm
-------
TABLE 5. CATCHBASIN
LOCATION
MONITORING
BAKER STREET
DATA
I
I
EVENT DATE 12/5/79
I
SAXPLE
SAMPLING
ROD
COD
TSS
VSS
TKN
TP
TYPE
TIME*
(minutes)
mg/I
mg/i
mg/I
mg/i
mg/I
mg/I
INFLUENT
0.0
270
540
540
1146.5
1041.4
167.7
126.8
9.2
—
0.18
0.50
0.5
252
795.7
103.4
—
0.22
1.0
317
555
867.0
122.4
8.2
0.24
1.5
846.1
108.7
—
0.05
2.0
312
530
525
642.3
79.5
—
0.04
2.5
280
161.6
26.3
2.2
0.07
15.0
142
—
165
174.2
26.8
—
0.06
23.0
130
142.7
20.5
—
0.05
24.0
127
70
103.9
18.1
—
0.06
25.0
105
99.3
15.9
—
0.06
26.0
122
345
573.5
148.4
7.6
0.13
.EFFLUENT
23.0
335
348.0
76.2
—
0.14
I
IPRE-SUMP
24.0
25.0
26.0
27.0
28.0
192
187
172
217
82
310
270
320
250
290
287.5
243.5
255.0
241.7
162.0
56.8
52.3
52.3
51.3
24.3
—
3.8
—
—
7.6
0.18
0.12
0.14
0.14
0.09
IPOST-SUMP
* Time since start of storm
-------
(..)
o
TABLE 6.
CATCHBASIN
LOCATION
EVENT DATE
MONITORING DATA
GLENNAVEN ROAD
12/5/79
I
I
ISAMPLE
SA}IPLING
BOD
COD
TSS
VSS
TKN
TP
I
I
TYPE
TIME*
I
(minutes)
mg/i
mg/I
mg/i
mg/i
mg/I
mg/i
INYLUENT
0.0
1075
1321.8
214.2
3.4
0.24
0.10
0.5
86
765
636.0
83.8
—
0.08
1.0
61
335
452.3
57.9
4.2
I
1.5
52
335
214.4
24.7
—
0.04
2.0
44
270
145.9
20.5
—
0.03
I
2.5
43
180
115.5
12.8
3.6
6.5
11
145
15.5
—
—
—
26.0
8
25
18.1
2.4
—
—
27.0
8
130
10.1
1.3
—
—
—
28.0
7
180
7.0
—
—
I
29.0
8
85
9.8
2.3
—
—
IEFFLUENT
26.0
45
740
308.9
93.0
—
0.12
I
27.0
35
500
175.5
41.7
4.7
0.15
I
28.0
35
295
155.7
38.4
—
0.14
I
29.0
35
260
136.4
34.4
—
0.08
I
30.0
35
255
178.6
42.2
3.4
0.08
31.0
35
255
147.3
35.9
—
0.09
IPRE-SUMP
27
210
208.5
22.9
IPOST-SUMP
—
—
—
—
—
—
* Time since start of storm
-------
TABLE 7
.
CATCHBASIN
LOCATION
EVENT DATE
MONITORING DATA
SPRING STREET
12/7/79
I
SAMPLE
SAMPLING
BOD
COD
TSS
VSS
I
TYPE
TIME*
(minutes)
mg/i
mg/i
mg/i
mg/i
INFLUENT
0.0
5.0
10.0
15.0
20.0
25.0
150
17
22
9
13
9
530
180
70
70
70
130
510.0
394.9
264.5
198.8
235.7
182.5
76.7
44.0
27.3
21.7
21.1
21.4
I
I
I
I
I
EFFLUENT
1.0
6.0
11.0
16.0
21.0
26.0
16
14
22
16
8
25
295
130
155
143
85
120
103.8
107.7
228.9
226.0
183.8
130.0
10.5
5.3
19.9
17.2
23.3
5.0
I
IPRE-SUMP
20
80
77.9
—
IPOST—SUMP
13
255
134.5
5.9
I
I
I
* Time since start of storm
-------
I TABLE
8.
CATCHBASIN MONITORING
DATA
I
I
LOCATION BAKER STREET
I
I
EVENT DATE 12/7/79
I
I
I
I
I
I
I
ISAMPLE
SAMPLING
BOO
COD TSS
VSS
I
I TYPE
TIME*
I
I
I
(minute8)
mg/i
mg/i mg/i
mg/i
I
IINFLUENT
0.0
80
880 2409.4
164.6
I
I
5.0
55
270 222.6
27.0
I
I
10.0
13
80 771.0
43.2
I
I
15.0
13
— 161.5
16.1
I
I
20.0
4
25 342.1
26.4
I
I
25.0
5
30 128.4
15.4
I
IEFFLUENT
1.0
42
45 50.9
2.0
I
I
6.0
42
155 70.8
—
I
I
11.0
45
130 62.8
—
I
I
16.0
20
285 65.1
1.0
I
I
21.0
26
125 51.8
—
I
I
26.0
24
75 54.4
1.0
I
IPRE-SUMP
20
55 4.5
6.2
I
IPOST-SUMP
21
— 54.5
—
I
I
I
I
I
!
I
I
I
I
(.)
* Time since start of storm
-------
I
I
I TABLE 9.
CATCHBASIN
MONITORING
DATA I
I
LOCATION
CLEN1JAVEN
ROAD I
I
EVENT DATE
12/7/79
I
I
I
ISAMPLE
SAMPLING
BOB
COD
TSS
VSS
I TYPE
TIME*
I
(mLnuteo)
mg/i
mg/i
mg/i
mg/i
IINFLUENT
0.0
76
380
1075.7
267.6
I
5.0
33
195
220.5
35.3
I
10.0
35
80
109.1
16.8
I
15.0
32
60
85.9
12.9
I
20.0
32
—
83.4
12.3
I
25.0
39
25
65.5
9.8
IEFFLUENT
2.0
82
235
106.6
10.7
I
7.0
72
155
118.3
14.1
I
12.0
75
—
159.0
37.4
I
17.0
76
260
101.8
7.6
I
22.0
75
105
167.7
19.1
I
27.0
66
70
164.6
17.3
IPRE-SUMP
39
215
—
—
IPOST-SUMP
83
290
84.9
7.1
* Time since start of storm
-------
I TABLE 10. CATCHBASIN MONITORING DATA
I LOCATION SPRING STREET
EVENT DATE 12/12/79
ISAMPLE SA}IPLING BOD COD TSS VSS
I TYPE TIME*
(minutes) mg/i mg/I mg/i mg/i
INFLUENT 0.0 270 918 20017.2 6422.1
10.0 75 118 305.4 79.0
20.0 23 70 207.3 36.2
I 30.0 19 60 187.6 15.3
I 40.0 16 70 145.7 30.1
I 50.0 8 50 114.9 31.3
IEFFLUENT 2.0 18 215 746.4 398.1
I 12.0 8 165 201.0 52.7
22.0 4 143 260.9 70.6
32.0 2 143 214.7 58.7
42.0 10 95 156.9 41.6
52.0 4 70 101.5 30.1
IPRE-SUMP 20 — 32.7 15.7
IPOST—SUMP 36 50 99.0 28.7
* Time since start of storm
-------
-J
TABLE
11.
CATCIIBASIN
LOCATION
EVENT DATE
MONITORING DATA
BAKER STREET
12/12/79
I
I
I
• 1
I
I
SAMPLE
SAMPLING
BOD
COD
TSS
VSS
I
TYPE
TIME *
(mlnute8)
mg/i
mg/i
mg/i
mg/i
INFLUENT
0.0
220
580
4399.8
2939.5
10.0
20
130
346.7
45.8
I
20.0
16
50
277.2
135.3
I
30.0
5
70
166.7
35.8
I
40.0
20
35
152.3
28.1
I
50.0
28
25
110.7
27.7
IEFFLUENT
2.0
12
60
132.9
43.1
I
12.0
19
178
120.3
42.5
I
22.0
15
143
77.9
30.3
I
32.0
13
70
58.3
20.3
42.0
11
12
58.6
22.9
52.0
5
12
48.1
21.1
PRE-SUMP
32
53
71.2
50.0
POST-SUMP
28
60
49.9
21.2
* Time since start of storm
-------
I
I TABLE 12.
CATCIIBASIN MONITORING
CLENIIAVEN ROAD
I
LOCATION
12/12/79
I
EVENT DATE
SA)4PLE
SAMPLING
BOB
COD TSS
VSS
I
I
TYPE
T IME*
I
I
(minutea)
mg/i
mg/i mg/I
mg/i
I
I
I
1403.9
IINFLUENT
0.0
90
260 1814.1
207.0
I
10.0
63
50 277.3
58.9
I
20.0
50
60 111.2
33.1
I
30.0
48
35 73.1
24.1
I
40.0
60
12 54.9
I
I
50.0
58
12 94.9
57.2
181.5
EFFLUENT
3.0
40
480 617.3
120.9
13.0
44
238 401.3
23.0
31
190 238.0
33.0
19
143 146.3
I
43.0
5
118 104.9
I
53.0
11
60 76.4
IPRE-SUMP
24
70 89.6
46.2
27.6
I
IPOST-SUMP
92
125 70.8
I
I
I
I
I
I
I
I
I ’)
* Time since start of storm
-------
TABLE
I
I
13.
CATCHBASIN MONITORING DATA
LOCATION SPRING STREET
EVENT DATE 12/27/79
ISAMPLE
SAMPLING
COD TSS
VSS
I
I TYPE
TIME *
I
(minutes)
mg/i mg/i
mg/i
I
INFLUENT
0.0
755 14299.2
4726.2
1.0
580 1905.2
275.5
5.0
310 791.7
169.6
10.0
115 624.0
91.5
15.0
83 490.6
88.4
30.0
103 287.5
78.9
I
I
45.0
103 234.9
97.1
60.0
— 585.2
101.5
IEFFLUENT
2.0
320 150.6
58.3
I
I
15.0
335 142.8
53.9
I
30.0
215 58.8
18.0
I
45.0
125 87.2
27.4
I
I
60.0
110 95.3
20.0
IPRE—SUMP
103 —
—
I
I
IPOST-SUMP
130 —
I
I
I
I
I
* Time since start of storm
-------
I
TABLE 14. CATCUBASIN MONITORING DATA
LOCATION BAKER STREET
EVENT DATE 12/27/79
SAMPLE SAMPLING COD TSS VSS I
ITYPE TIME* I
(minutes) mg/I mg/i mg/I I
INFLUENT 0.0 355 4378.5 776.6
1.0 215 941.9 282.4
5.0 — 232.8 57.1
I 10.0 — 165.5 48.3
I 15.0 90 142.1 31.5
I 30.0 35 129.1 28.3
I 45.0 30 — —
I 60.0 70 — —
IEFFLUENT 1.0 170 409.8 137.6
15.0 140 346.0 86.6
30.0 75 195.0 44.4
45.0 70 112.2 26.7
60.0 30 88.8 23.0
PRE-SUMP 30 — —
POST-SUMP 70 — —
* Time since start of storm
-------
TABLE 15.
CATCHBASIN
LOCATION C
EVENT DATE
MONITORING DATA
LENHAVEN ROAD
12/27/79
ISANPLE
SAMPLING
COD
TSS
VSS I
TYPE
TIME*
I
(minutes)
mg/i
mg/i
mg/i
INFLUENT
0.0
440
2887.4
2245.8
1.0
220
357.8
171.6
5.0
30
431.8
339.4
I
10.0
65
113.3
42.5
15.0
60
41.7
26.2
30.0
30
48.2
25.5
45.0
40
68.8
36.4
60.0
—
50.3
20.5
IEFFLUENT
1.0
20
98.9
75.3
I
15.0
420
680.2
198.5
I
30.0
120
192.1
65.1
I
45.0
110
87.3
32.0
I
60.0
70
47.4
15.0
IPRE-SUMP
65
—
—
IPOST-SUMP
—
—
—
01
* Time since start of storm
-------
TABLE 16.
CATC1IBASIN MONITORING
LOCATION SPRING STRE
EVENT DATE 12/28/79
DATA I
ET
.
ISAMPLE
SAI(PLING
COD TSS
VSS I
I
I TYPE
TIME*
I
(minuteB)
mg/i mg/i
mg/i
IINFLUENT
0.0
430 267.2
143.6 I
48.5 I
I
1.0
155 184.7
I
I
5.0
156 64.8
25.0 I
10.0
110 132.2
I
15.0
106 23.2
—
I
20.0
120 143.5
115.1
I
30.0
155 230.2
73.3
I
40.0
130 253.3
101.2
I
I
50.0
107 142.4
30.9
I
IEFFLUENT
1.0
1073 819.3
100.4 I
I
15.0
118 1006.9
I
I
30.0
120 1144.4
I
I
45.0
96 533.4
I
I
60.0
73 447.1
46.7
I
I
75.0
98 2350.0
109.8
I
IPRE-SUMP
- -
-
I
IPOST—SUMP
— -
—
* Time since start of storm
-------
CATCWASIN MONITORING DATA
LOCATION BAKER STREET
EVENT DATE 12/28/79
I TABLE 17.
SAMPLE
TYPE
SAMPLING
fl *
(minutes)
COD
mg/i
TSS
mg/i
VSS
mg/i
INFLUENT
0.0
370
1574.9
1113.3
1.0
346
1202.8
730.3
5.0
188
591.2
128.2
10.0
170
759.8
134.5
15.0
156
285.8
107.3
20.0
93
477.3
80.8
I
30.0
118
168.0
62.1 I
40.0
118
206.9
52.0 I
50.0
80
235.5
90.8
EFFLUENT
1.0
163
118.9
69.3
I
15.0
123
92.0
29.7
I
30.0
78
82.8
43.8
I
45.0
73
54.6
31.3
I
60.0
70
82.8
43.4
I
75.0
63
67.9
33.5
IPRE-SUMP
-
—
IPOST-SUMP
-
64.7
29.7
* Time since start of storm
-------
TABLE 18. CATCIIBASIN MONITORING DATA I
LOCATION CLENHAVEN ROAD I
EVENT DATE 12/28/79 I
ISAMPLE SAMPLING COD TSS VSS I
TYPE TIME *
(minutes) mg/i mg/i mg/i I
INFLUENT 0.0 258. 6167.3 4245.2
1.0 170. 343.7 67.0 I
5.0 — — — I
10.0 — — —
15.0 70. 45.7 14.6 I
20.0 45. 18.1 5.8 I
30.0 49. 57.7 19.7 I
40.0 — — — I
50.0 2. 51.2 13.5 I
EFFLUENT 1.0 131. 164.1 55.1 I
15.0 95. 110.3 35.8 I
30.0 58. 79.6 31.7 I
45.0 25. 60.9 32.5
60.0 35. 50.9 28.1 I
75.0 18. 34.4 16.7 I
PRE-SUMP — 14.6 12.0 I
POST-SIJMP — 55.3 27.1 I
* Time since start of storm
-------
I TABLE 19. CATCIBASIN MONITORING DATA I
I LOCATION SPRING STREET I
I EVENT DATE 1/11/80 I
SAMPLE SAMPLING BOD COD TSS VSS
I TYPE TIME * I
I (minutes) mg/i mg/i mg/i mg/i I
I I
I I
IINFLUENT 0.0 225 968 31558.5 8211.8 I
I 2.0 70 757 5044.8 723.1 I
I 10.0 11 238 1808.1 153.0
I 20.0 22 238 3292.2 177.5
30.0 5 95 351.8 52.1
40.0 5 118 256.2 46.1
EFFLUENT 2.0 65 730 569.4 247.0
10.0 33 213 217.7 65.3
20.0 80 382 89.5 49.9 I
30.0 43 213 74.5 40.7
I 40.0 38 118 52.8 37.6
I 50.0 21 118 98.8 49.0
IPRE-SUMP 7 48 15.9 4.9
IPOST—SUMP 16 — 115.2 28.1 I
‘.0
* Time since start of storm
-------
U,
I
I
TABLE 20. CATC1U3ASIN MONITORING DATA I
LOCATION BAKER STREET I
EVE1IT DATE 1/11/80 I
ISAMPLE SAMPLING BOD COD TSS VSS
I TYPE TIME* I
I (minutes) mg/i mg/i mg/i mg/i
I
I
IINFLUENT 0.0 110 863 32250.2 10497.5 I
I 2.0 60 843 3675.1 1173.8 I
I 10.0 16 260 591.8 144.4 I
I 20.0 14 190 598.8 145.4 I
I 30.0 4 143 497.9 100.3 I
I 40.0 3 118 341.9 71.8 I
IEFFLUENT 2.0 33 333 326.5 118.8 I
I 10.0 35 260 259.8 91.0 I
I 20.0 27 188 170.5 61.1 I
30.0 26 167 60.3 47.9 I
40.0 22 118 76.3 28.9 I
50.0 24 118 74.3 26.5
IPRE-SUMP 26 70 3.2 1.2
IPOST-SUMP 7 143 129.4 42.4 I
I
* Time since start of storm
-------
C . ,’
TABLE 21.
I
I
CATCRBASIN MONITORING
LOCATION CLENIIAVEN
EVENT DATE 1/11/80
DATA I
ROAD
SAMPLE
SAMPLING
SOD
COD TSS
VSS I
I
I TYPE
TIME*
(minutes)
mg/I
mg/i mg/i
mg/i
PRE-SUMP
0.0
2.0
10.0
61
48
19
757 10550.1
260 429.0
238 182.7
8210.6 I
170.0 I
56.4
I
20.0
30.0
40.0
25
10
9
95 133.1
95 127.9
70 96.5
50.2
39.9
36.0
EFFLUENT
1.0
10.0
20.0
30.0
63
62
26
21
188 217.5
238 274.3
167 307.9
118 122.5
86.5 I
64.4
32.4
I
40.0
18
— 236.4
146.9
I
50.0
18
70 93.9
I
IPRE—SUMP
27
118 36.6
IPOST—SUMP
22
358 141.6
44.9
* Time since start of storm
-------
TAflLE 22. CATCIIBASIN MONITORING DATA I
LOCATION SPRING STREET I
EVENT DATE 1/14/80 I
I
ISAMPLE SAMPLING COD TSS VSS TEN T-PHOS
I TYPE TIME*
I (mlnute8) mg/i mg/i mg/i mg/i mg/i
INFLUENT 0.0 885 16251.9 4537.7 14.0 13.60 I
10.0 155 546.0 128.0 2.2 9.10
20.0 107 118.2 29.3 — 8.00
I 30.0 70 143.0 26.6 1.2 1.30
40.0 53 73.1 21.0 — 4.40
50.0 48 86.5 23.4 1.5 6.40
EFFLUENT 1.0 166 273.4 66.9 1.9 12.50
10.0 115 205.9 49.5 1.9 5.00
20.0 45 127.5 30.4 1.5 4.20
30.0 97 92.9 24.4 1.9 8.10
40.0 53 85.1 23.2 — 4.00
50.0 45 59.5 23.2 1.4 3.90
IPRE—SUMP 107 52.1 14.1 1.2 6.30
IPOST—SUMP 95 51.8 13.3 1.1 —
(7 1
F’)
—I
* Time since start of storm
-------
I I
I TABLE 23. CATCUBASIN MONITORING DATA I
LOCATION BAKER STREET I
EVENT DATE 1/14/80 I
SAMPLE SAMPLING COD TSS VSS TEN T-PHOS
TYPE TIME*
I (mlnute8) mg/I mg/i mg/i mg/i mg/I
IINFLUENT 0.0 578 2364.6 765.3 7.8 7.00 I
I 10.0 143 259.0 109.2 1.7 5.20
20.0 115 192.7 32.4 — 5.10
30.0 93 142.9 34.7 1.6 5.10
40.0 118 119.9 19.7 — 3.80
50.0 — 78.6 41.7 — —
EFFLUENT 1.0 215 83.2 28.9 1.8 —
10.0 190 80.0 26.2 2.2 —
20.0 137 70.4 26.1 1.9 8.10
30.0 170 56.1 21.1 1.4 2.50
40.0 155 60.3 23.8 — 2.80 I
50.0 118 208.3 68.9 2.1 1.40
IPRE—sUKP 107 27.6 11.6 1.5 2.60
POST-SUMP 188 247.9 82.4 3.0 —
(71
(.1
* Time since start of storm
-------
I I
I TABLE 24. CATCHBASIN MONITORING DATA I
LOCATION CLENHAVEN ROAD I
EVENT DATE 1/14/80 I
I I
I I
I I
ISAMPLE SAMPLING COD TSS VSS TKN T-PHOS
TYPE TIME *
(minuteB) mg/i mg/i mg/i mg/i mg/i
INPLUENT 0.0 668. 13445.3 8424.8 11.3 —
10.0 200. 660.9 104.9 3.7 5.70 I
20.0 170. 129.0 45.5 — 7.30 I
30.0 162. 98.5 35.7 2.6 — I
40.0 137. 81.9 30.6 — 9.50 I
50.0 123. 89.6 38.4 — 8.10 I
IEFFLUENT 1.0 395. 260.0 81.0 7.0 2.80 I
I 10.0 188. 385.9 117.7 5.1 8.20 I
I 20.0 223. 3.8 219.1 72.5 6.30 I
I 30.0 190. 2.9 145.5 54.2 9.60 I
I 40.0 123. — 111.3 41.6 10.30 I
I 50.0 155. 2.4 106.5 38.4 6.30 I
IPRE-SUMP 73. 1.8 27.8 12.9 5.50 I
IPOST-SUMP I
* Time since start of storm
-------
TABLE 25. AVERAGE FLOW RATES FOR RUNOFF EVENTS MONITORED
Runoff Event
Date SPRING ST. BAKER ST. GLENIIAVEN RD.
(Flow Rates in cfs)
12/5/89 0.050 0.025 0.008
12/7/79 0.037 0.022 0.017
12/12/79 0.039 0.018 0.014
12/27/79 0.045 0.027 0.023
12/28/79 0.045 0.015 0.012
1/11/80 0.047 0.023 0.022
1/14/80 0.047 0.022 0.030
55
-------
tilt T CTPAINFRC
TABLE 26.MASS AND PERCENT REMOVALS WITHOUT
C 0* (* F 6* H I
12/05/79 38120 6309 83 4 4419 360 91 8 3872 394 89 8
12/07/79 2780 3040 —9 4 330 126 61 8 1630 1450 10 9
12/12/79 70072 5615 91 9 22092 2177 90 1 4296 2776 35 3
12/27/79 88356 2376 97 3 25876 789 96 9 7065 4911 30 5
12/05/19 6657 414 93 8 903 93 89 1 4408 55 98 8
12/07/79 3820 336 91 2 2780 827 70 5 1260 700 44 4
12/12/79 8353 760 90.9 4920 276 94 4 1363 727 46 6
12/27/79 8304 3140 62 2 1697 868 48 8 3050 1322 56 4
12/05/79 6 83 75 5 -10 5 71 20 88 5 1340 172 87 2
12/07/79 1863 581 68 8 252 75 70 2 556 734 -32 0
12/12/79 2823 2891 —2 4 2076 574 72 4 443 1430 —22 2
11/27/79 9540 2594 72 8 6936 905 87 0 2159 1736 19.6
U i
TARIF 27. MASS AND PERCENT mFM0V*lc WITH INLET STRAINERS
* All mass units are In grams
Column Reference
A TSS Influent H IF Influent
B ISS Effluent N TP Fffluent
C S Removal 0 0 Removal
o yss Influent
E 755 Effluent
F S Removal
Spring Street
Baker Street
Glenhaven Road
579 222
343 157
1373 154
2550 250
161 188
473 115
344 1511
175 317
436 177
L
61 7
54 2
888
90 0
-16 7
7 7
- 339
-81 1
59 4
M N ’
3484 640
1692 181
218 45
0
81 6
893
79 4
12/28/79
01/11/80
0 1/14/80
12/28/79
01/11/80
01/14/80
12/28/79
01/11/80
01 / 14/80
Spring Street 5498*
— 135723
69333
Baker Street 6811
- 59328
— 5901
Glenhaven Rd 7338
— 17536
21109
35570’
4245
3332
922
1815
1012
762
2336
1204
96 9
95 2
86 6
96 9
82 7
89 6
86 7
95 0
28 88 2 *
30036
19190
3111
18965
1875
4596
13036
16222
3064
1684
859
464
702
357
305
811
5402
89 4
93 8
95 5
85 1
96 3
81 0
93 4
93 8
68 9
TEN TEN S TP TP S
5603*8908*_58 9 -* -* lnf.Eff Remov lnf Eff Remov
7743 6823 11 9 1084 1078 0 6 88 40 54 5 172 148 13 9
5307 2056 61 3
2041 1053 48 6
3778 2221 41 2 324 313 3 4 14 20 —42 9 39 17 56 4
2067 1804 12 7
885 561 366
2306 1632 29 2 262 388 —48 1 32 546 -16 0 79 109 -38 0
2729 2333 14 5
S COD Influent
H COD Effluent
I S Removal
J ROD Influent
K BOO Effluent
S Removal
-------
related pollutant removals due to the catchbaslns were extremely
high. Although not measured, it Is uni Ikely that the overall
removal efficiencies of the catchbasins would drop to low levels
at higher flow rates. Table 27 presents similar results as Table
26 for the events monitored with inlet strainers. The net effect
of the inlet strainers was a removal efficiency improvement of I—
10% percent.Nutrient data collected indicated no realizable
treatment gain.
Figures 15—lB present typical plots of the catchbasln
data. The plots Illustrate three important findings; I) the
influent characteristics to the catchbasins were surprisingly
consistent over a series of events; 2) no significant effluent
“first flush” was observed even though infiuent levels rose
dramatically; and 3) effluent concentrations yielded an almost
immediate baseline which the influent gradually tapered to meet.
6.2 . j Resu-1ts-Sum SedIm n±
As noted in Chapter 5, suinp sediment quality and level
was monitored prior to each measured runoff event. Figures 19—21
present composite sieve analyses results for Spring Street, Baker
Street and Glenhaven Road, respectiveiy. Comparison of these
data to other samples collected throughout the United States
yields very comparable results. The results of firing each
sieved fraction separately, are shown as a residual sieve
analysis on the bottom of each figure. The difference between
the two curves represents the percent volatile material present
in the samples. In all cases, the percent volatile organic
matter found was very high for all fractions, averaging
approximately 70%.
Table 28 presents the monitoring results of sedIment in
the catchbasin sumps over the two month evaluation period. As a
means of roughly cross—checking the monitoring data, the
approximate Increase In mass in the sump was compared to the
total measured amount deposited in the sump during the runoff
events. Assuming that the sump materials have a specific gravity
of 1.4, indicative of the mix of sand and organics found,
computed accumulations of solids were 111, 117 and 39kg for
Spring Street, Baker Street and, Gienhaven Road, respectively.
With the exception of Spring Street, these results compare
reasonably with the 349, 91, and 56 kg, respectively, deposited
during the monitored runoff events (cumulated from Table 27).
Although it is difficult due to the limited data set avai iabie to
predIct the exact dry weather additional accumulated load, some
dry weather load would have to be added to these numbers. The
phenomenon of dry weather accumulation is discussed in more
detail in the next section. Even with the addition of a miminal
dry weather load there is reasonable comparability between the
57
-------
4000
TIME0 315585mg/I
TIME I mmite 5044 7mg/I
SPRING STREET
C
a,
0
C
0
0
0
0
0
I—
C),
0:,
3000
2000
1000
0
/ TI 79
0
IS
30
Time (minutes)
1/11/80
Figure 15. Typical plots of Total Solids influent/effluent
concentrations.
45
60
LEGEND
Influent
Effluent — —
-------
4000
TIME 0 32,250 mg/I
E
C
0
C
0
U
0
0
0
I-
3000
2000
1000
0
TIme (minutes)
Figure 16. Typical plots of TSS influcnt/effluent concentrations.
LEGEND
Influent
Effluent — —
BAKER STREET
U,
0
I / II / 80
12 / 7/79
IS
45
-------
GLENHAVEN ROAD
D
Time (minutes)
Figure 17. Typical p]ots of COD Influent/effluent concentrations.
LEGEND
Influent
Effluent — —
-------
350
C)
0
300
250
200
250
100
50
0
Time (minutes)
Figure 18. Typical plots of BOL) influenh/effluent Loncentrations.
BAKER STREET
12/7/79
LEGEND
Influent
L tluent — —
0
30
45
-------
U.S. Standard Sieve Numbers
100
90
80
70
60
w
50
c 40
U-
30
20
I0
0
Grain Size in mm
Figure 19. Composite plot of sediment
analysis for Spring Street.
16 20 30 40 50 70 tOO 140
4 2 I 0.6 0.4 0.2 0.1 0.075
LEGEND
Sediment Fractions
Tss
Solids remaining
of fer firing
62
-------
U.S. Standard Sieve Numbers
.0
L I-
Grain Size in mm
Figure 20. Composite plot of sediment
analysis for Baker Street
4 6 810
16 20 30 40 50 70 100 140 200
100
90
80
70
60
50
40
30
20
I0
0
-
-..----v
‘
\
. _ - —
—.-—-—-
h b1 ç
.:s __
ki 1
4 2 I 0.6 0.4 0.2 0.1 0.075
LEGEND
Sediment Fractions
TSS
Solids remaining
after firing
63
-------
l00
90
80
70
60
30
20
I0
0
Figure 21. Composite plot of sediment
analysis for Glenhaven Road.
U.S. Standard Sieve Numbers
4 6 8 tO 16 20 30 40 50 70
4 2 I 0.6 0.4 0.2 0.1 0.075
Grain Size in mm — — -
LEGEND
Sediment Fractions
Tss
Solids remaining
after firing
64
-------
accumulations measured in the sump and, the sum of residuals from
the runoff events. This data further corroborates the monitored
evidence Indicating catchbasin performance to be very high.
TABLE 28
MONI-TOR-ING QE SUMP I.EVELS IN CATCHBASINS
Level’ Level’ Level’
Spring St. Baker St. Glenhaven Rd.
(Inches) (Inches) (inches)
12/5 — 74 70
12/7 70 75 69
12/12 68 ii 66
12/27 68 71.25 68.50
2/28 68 71 68
I/lI 67.25 71 72
1/14 66.30 71.50 69.50
1/29 66.50 71.50 69.50
Overall increase (Inches) 3.5 2.5 0.5
*lndicates Istance to sediment from ca*chbasln rim In inches
6.3 Summary f Results—Influent Strainer-s
As noted in Chapter 5, inlet strainers were specially
designed, constructed and installed in each of the three
monitored catchbaslns during the last three storm events. As
Indicated In Table 3, the influent strainers were Instal led Just
prior to the runoff event occurring on 12/28/79 and maintained
for two weeks subsequent to the final monitored event (until
1/19/80) to give additional data on dry weather accumulations.
Table 29 presents a summary of the influent strainer data. Data
shown includes; accumulation period (if dry weather), total dry
mass of solids collected and percent organic. The inlet
strainers collected substantial amounts of materIals durIng dry
weather. As may be noted from the data, Spring Street exhibited
continuously higher accumulation rates than Baker Street and
Gienhaven Road, with significantly more of the matter collected
inorg8fliC sand and dirt. This would be indicative of greater
wash—off soils loadings from the open areas along Spring Street
as well as the much greater traffic density on Spring Street,
being a major local commuter road, versus the other two sites
65
-------
TABLE 29. RESULTS OF THE INFLUENT STRAINER STUDIES
Total Dry Mass Collected — grams Percent Volatile
Date A B C D E F G H
I. Wet Weather Accumulation (During Event)
12/28/79 X 1293 5.5 12.2 17.0 68.2 74.3
1/11/80 X 984 556.7 56.7 16.8 34.2 52.3
1/14/80 X 159 214.8 53.8 24.6 60.8 74.4
II.Dry Weather Accumulations (Between Events)
1/11/80 14 3311 387 102.7 34.2 65.8 70.4
1/14/80* 2 3246 245 718.7 22.9 57.8 71.8
1/29/80 15 1758 539 194.0 24.0 54.2 76.2
Legend
A — Antecedent dry period days
B — Runoff event
C — Spring Street
D — Baker Street
E - Glenbaven Road
F — Spring Street
C — Baker Street
H - Glenhaven Road
*
Heavy accumulations due to high intensity short duration storm evening of
1/11/80 0.49 inches rain.
66
-------
being primarily residential. The major fraction of collected
materials from Baker Street and Glenhaven Road was organic leaves
and decomposing lawn clippings, as exhibited by the high organic
content.
Pollutant removal of the influent strainers during
storm events was small in relation to that removed in the sump
during the same event, ranging from two to ten %. During dry
weather significant accumulations were observed in the inlet
strainers, but these accumulations by weight were small In
relation to the mass removed in the sump during a storm event.
Although, the design size of the inlet strainers used in this
program was set at an initial number 8 mesh, (0.0937 in. 2.36mm)
this size could have been reduced to gain greater removals. Even
so, It Is unlikely that the overall efficiency of the units would
be great enough to warrant their wide spread use.
The reasons for this conclusion are twofold. First, the
Inlet strainers detain large amounts of materials, forming a
filter cake of progressively finer opening as deposition occurs.
This phenomenon would lead to rapid clogging and subsequent
localized flooding due to blockages of the catchbasln inlets. It
is estimated that required maintenance frequency of the inlet
strainers would be weekly making overall maintalnenCe costs
high. Secondly, detained materials in the inlet strainers are
subject to decomposItion between storms as are materials In the
catchbasin sump. Unlike the catchbasin sump, the materials in
the inlet strainers are held above the overflow outlet making
them available for dischage during the next runoff. Organics
entrained in the Inlet strainers would tend to break down to fine
settleable and colloidal particles unsuitable for removal by the
catchbasin sump. In contrast, decomposing materials in the
catchbasin sump would tend to migrate into the pores between the
grit particles. The overall result of a poorly maintained inlet
filter, (over one week in cleaning interval) could be local
flooding and increased pollutant discharge to the receiving sewer
due to build up and decomposition in the strainer.
6.4 RevIew t Catc-hfraslfl f4011-itor-ln9 Data
The catchbasin monitoring program collected a large
amount of simultaneous performance data on three test catch—
basins in the West Roxbury section of Boston. The catchbasins
were divided into two types, direct discharges from the gutter
Into the receiving sump and discharge to a transmission sump
prior to the receiving sump. The latter type, as shown by the
Spring Street catchbasin, offers seemingly better energy and
thus turbulence dissipation. However, this could not be verified
by the performance data, In that removals from all three
catchbasins were comparable.
67
-------
The effects of higher traffic density were dramatically
Illustrated in the very high influent levels monitored on Spring
Street, relative to the other two sites. This effect was
Illustrated during both dry weather, where significant deposition
occurred and, during runoff. See study by Saheen.
Initially, pre—sumP samples indicated moderate
pollutant levels. In almost every case initial effluent
concentration levels were less than the measured pre—sump sample,
even though the influent concentrations rose dramaticaily at the
same time yielding no significant “first flush” effects. Overall
sol Ids related pollutant removals were generally quite high with
few exceptions, although periodic negative removals or fiushout
were observed for all parameters except VSS. Catchbasin removals
for nutrients generally were negligible to negative, indicative
of the transfer of nutrients from being bound in sol ids in the
sump to dissolved, after decomposition in the sump.
Sediment accumulation analysis indicated that the
materials deposited in the sump at a rate such that cleaning
every six months to one year, dependent on conditions, would
maintain observed pollutant removals. Analyses of the sump
sediments yielded data consistent with that generated in other
cities. No appreciable difference was observed in the sediment
characteristics between the initial sample (old material left as
residual of cleaning operations) and those collected after
significant fresh deposition.
inlet strainers collected substantial amounts of dry
weather and runoff Induced solids, but their overall
effectiveness and potential for widespread utilization was deemed
limited by high maintenance requirements vs. limited pollutant
removal gains.
68
-------
CHAPTER 7
CATCHBASIN CLEANING COSTS IN CITY OF BOSTON
7 • I Fore,ror
In this chapter excerpts from an analysis conducted on
the City of Boston sewer system for the Boston Water & Sewer
Comm i ss ion (BW&SC) by EDP are presented (12). Avernga
maintenance costs for cleaning of catchbaslns (based on present
operating data) are presented in section 7.2. The costs
generated were then compared to data for other cities of similar
size end weather conditions in section 7.3. In section 7.4 the
relative economics of increased catchbesin cleaning frequency
are assessed using Boston data for combined sewer systems.
7.2 Büst’on Ca-f’c1ibe-s1i C1eeii1i Ces+s
Cost estimates were generated for cleaning of
catchbesiflS as presently being conducted by BW&SC crews. Costs
were broken down into four categories: labor (including
overhead), energy usage, vehicle and equipment maintenance, and
finally, disposal costs. The break—down and total cost figures
are sumarized in Table 30. Rates of catchbasln cleaning were
obtained from the analysis of crew performance data supplied by
BW&SC and through direct observation of cleaning operations by
EDP personnel.
After careful review of labor rates with the BW&SC
financial division, labor costs were estimated at $8.83 per
hour for catchbasin cleaners. These average figures include
overtime and burdening factors. Under present conditions an
average of 5.2 catchbasins are cleaned per man per day. The
resulting labor cost is $13.60 per basin cleaned. This cost is a
citywide overall average based on 1979 reported results and
Includes travel and paid break—time.
Energy costs are based on average vehicle fuel usage.
Catchbasin cleaning trucks were determined to average 10 gallons
per day based on BW&SC reported volume data. Fuel was estimated
at $1.25 per gal Ion.
Fuel costs could not be linked to miles traveled due to
the large idling times and usage of fuel for operating cleaning
machinery. Resulting energy costs were $2.40 per basin.
Vehicle and equipment maintenance costs were more
difficult to estimate. Maintenance costs were estimated to be
proportional to vehicle fuel costs. A proportionality constant of
2 was determined by examining the expenditures for 1980. For 1980
69
-------
the following figures were determined for the entire 144 vehicle
BW&SC fleet:
Maintnenance $200,000
Insurance 75,000
Fuel 148.000
$423,000
Resulting maintenance costs are $4.80 per basin.
Disposal costs can and do vary rapidly. In the fal I,
1980, the BW&SC was forced to change Its dump site. The new
(temporary) site charges $15 per dump, regardless of the size of
truck.
An analysis of catchbesin dimensions of approximately
80 catchbasins representatively scattered throughout I-he BW&SC
sewerage system indicated that the average sump and total volumes
equal 2.4 and 3.6 cubic yards (1.83—2.75 cubic meters),
respectively. Disposal costs range from $7.20 (sump f ii led) to
$10.80 (entire basin tilled) per cleaned catchbasin using an
average catchbasln cleaning truck volume of 5 cubic yards (3.81
cubic meters).
As shown in Table 30, average Boston catchbasin
cleaning costs range from $28.00 to $31.60.
7.3 Boston/National Catchbasln Cleaning Cost Comparison
National catchbasin cleaning cost figures vary
considerably. The average cost per basin, based on 17 communities
with high snow falls, is $15.8 per basin with a standard
deviation of $6.8 per basin (ENR = 3000)(I). Cleaning costs per
basin ane expected to be higher as Boston catchbasin sumps (2.4
cubic yard or 1.83 cubic meters) are iarger than the national
average sump volume (I) (1.7 cubic yards or 1.30 cubic meters).
Based on 10 communitIes, a national average of $10.4 per cubic
yard is reported with a standard deviation of $11.6 per cubic
yard (1). For a typical Boston basin, the national average would
predict $37 per basin to clean where the basin is full and $25
per basin to clean where only the sump is full. Similar estimated
BW&SC costs (shown in Table 30) of $31.60 and $28.00 per basin
are within the national averages for comparable situations and
techniques. These costs reflect labor, energy, maintenance and
dumping charges. No cost of capital investments are included.
70
-------
TABLE 30. PRESENT CATCHBASIN CLEANING COSTS
(1980, ENR 3OOO, BOSTON)
Based on Full Basin Volume Based on Full Sump Volume
(97 ft 3 per basin) (65 ft 3 per basin)
Labor 13.60 13.60
Energy 2.40 2.40
Vehicle & -
Equ I pment
MaIntenance 4.80 4.80
Disposal 10.80 7.20
Total S 3i.60 28.00
71
-------
Sect I on 7.4. £ mi Aji i siS i Ir i
Cleaning Fre uenc
in this section two typical scenarios are examined using
Information generated from an analysis of catchbasin cleaning
maintenance practices in the City of Boston (12). First, the
issue of whether Increased catchbasin cleaning frequency in
combined sewer systems is worth the benefits of decreased Waste—
water Treatment Plant (WWTP) solids handling Is examined using
a 162 acre (65.6 ha) test area in West Roxbury, Boston.
Second, pollutant removal I cost effectiveness of increased
catchbasin cleaning frequency practices versus in—line storage
and swirl treatment technology is examined, in both cases an
existing WWTP is assumed to exist with adequate solids
handling capacity.
Case
Pertinent data used in this analysis are discussed in detai i
elsewhere (12) and are summarized in Table 31. in that
study an empirical catchbasln solids accumulation simulation
model was developed and used to estimate solids retained In
typical Boston catchbasins as a function of intervals between
catchbasin cleaning and solids input during storm events.
These results are summarized In Table 31.
If solids are not removed by the catchbasins then the
solids will increase both sewer cleaning and solids removal
costs at the treatment plant. To address this problem
catchbasln cleaning costs were estimated from the previously
described BW&SC data for cleaning frequencies of 2, I and 1/2
years for the West Roxbury test area (85 basins). Present
values were calculated for a twenty year planning period and a
6 1/8% annual discount rate. Present worth of these annual
costs over the twenty year period for the West Roxbury test
area are $15,200, $23,300 and $48,500 respectively for
cleaning intervals of 2, 1 and 1/2 years.
Storm sewer cleaning costs in the West Roxbury test
area estimated for comparison with catchbasin cleaning costs.
For the estimate it was assumed only lines 24 inches (61 cm)
and larger would need to be cleaned. (1) Average cleaning of
storm sewers in the entire system in the West Roxbury test
area Is $18,500 (1980, ENR = 3000). Present values were
calculated for the West Roxbury cleaning operation based on a
cleaning frequency of every 10 years and every 5 years for
the 20 year planning period and 6 1/8% discount rate. (1) The
present worth of sewer cleaning once every ten years is $21,500
(1980, ENR3000). The present worth if cleaning is needed
every 5 years is $42,900.
72
-------
TABLE 31. PERTINENT DATA — WEST ROXBURY, BOSTON TEST CASE
Pertinent Data — West Roxbury, Boston Test Case
A. Wtershe-d Chpra ter-isti s
• Area 105 acre (42.7 ha) single family residential and
55 acre (22.41 ha) open space.
• Runoff coefficient residential area = 0.45
• Curb/gutter density .097 miles/acre (0.38 km/ha)
• No.catchbasins = 85 (1.24 basins/acre or 3.05
basi ns/ha)
B. Catchbasln Dimensions ( Aver-age )
• Sump volume 64.8 ft 3 (1,84 m 3 )
• Total volume 97.2 ft 3 (2.75 m 3 )
• Total depth 7 ft (2.1 m)
C. Catchbasin CIeriing Cost-s
(Boston, 1980, ENR = 3000)
• 2 year frequency — $31.60/cleaning (97 ft 3 removed)*
• 1 year frequency — $26.25/cleaning (49 ft 3 removed)
• 1/2 year frequency — $25.15/cleaning (39 ft 3 removed)
• Assume solids density — 110 lb/ft
0. Storm Sewer Cienlng ( Test Are-a )
(Pipes exceeding 2 ft (0.6 m) diameter)
• Footage = 4837 ft (1475 rn)
• Average cleaning cost = $3.83/ft ($1.17/rn)
(1980, ENR = 3000)
E. WWTP Solids Hendliny Costs
• Operational costs for thickening, vacuum filtration,
disposal & maintenance: $193—$581/ton solids handled
($175.5 — $528.2/metric ton solids handled
(Boston, 1980, ENR3000)
* Determined from empirical catchbesin performance model
(12)
73
-------
WWTP solids handling costs were included for comparison
with solids removal through catchbasin cleaning. it was
assumed that the WWTP solids handling capacity was adequate,
that Is, solids loading changes caused by varying catchbasin
cleaning policies would not require new facil ities. Only the
operating costs would be increased by an increasing solids
load.
The greater Boston area presently has two major
wastewater treatment plants. Plans are being implemented for
facilities to reduce sludge volumes and prepare sludges for
land disposal. Stormwater treatment plants have also been
constructed such as the Cottage Farm facility and plans are
being developed for major stormwater treatment facilities
throughout the area including the BW&SC service area. Due
to the dynamics of the system it was deemed appropriate to
examine the range of sludge handling costs nationally in
terms of establishing general operating policies for
Boston.
Costs indicated in Table 31 include pumping, line
stabilization, In some cases thickening either by gravity or
vacuum, transportation, disposal, and maintenance of the
disposal facility. Costs are operational only; no
construction costs are included. The cost range is for a
city with 25,000 combined sewered acres.
It was assumed that all solids captured by a catchbasin
under a given cleaning policy would be captured by the WWTP
under a less efficient catchbasin operating policy. Zero
loss to overflows was assumed. In addition, ten percent of
the removable solids escaping the catchbasifl were
considered as deposition and removed by sewer cleaning. The
WWTP sal ids handl ing costs for different catchbasin
cleaning policies are presented in Table 32.
Comparisons between cleaning frequencies and WWTP solids
loadings were made for cetchbasin cleaning frequencies of
2,1 and 1/2 years. The results are presented in Table 33.
The two year frequency would plan to clean relatively
full basins. The 1 year frequency would only have suinp
volumes to clear. The 1/2 year frequency would maintain
the basins below the performance breakthrough curve at al I
times. Cost estimates were made using both the low and high
range WWTP solids handling figurQ. The effect of Increased
sewer cleaning needs was simulated by assumIng a decrease
in catchbasin cleaning frequency that would double the need
to clean sewers. The “no sewer cleaning” assumption is also
included. These results are also presented in Table 33.
74
-------
TABLE 32. WWTP SOLIDS HANDLING COSTS W. ROXBURY CASE EXAMPLE
Catchbasin Annualized Annualized Annual WWTP Total
Cleaning Weight Solids Weight Solids Solids Handling Present
Frequency Removed per Arriving at Cost per Catch Value***
(years) Catchbasin WWTP per —basin Solids
(lb)* Catchbasin** $193/ton—$581/ton $193/ton
C lb)
2 5335 3485 $336.30 $1012.39 324.5—976.7
5390 3430 $331 .00 $ 996.42 319.3—961.3
1/2 8580 240 $ 23.16 $ 69.72 22.3— 67.3
* See part C Table 31; also total annual solids input per
catchbasin 9800 lb.
** Note 10% of solids escaping catchbasin deposit In sewer
lines
*** 6 1/8%, 20 year planning period
TABLE 33. COMPARATIVE ECONOMICS OF CATCHBASIN CLEANING FREQUENCY
(BOSTON CONDITIONS, 1980, ENR=3000)
West Roxbury Test Area, Data
Present Value Costs* ($1000)
Catchbasin Sewer
Cleaning Cleaning Catchbasin Sewer SolIds Handling Total
Frequency Frequency Cleaning Cleaning WWTP**
(Years) (Years)
2 10 15.2 21.5 324.5 361.2
2 5 15.2 42.9 324.5 382.6
1 10 25.3 21.5 319.3 366.1
1/2 10 48.5 21.5 22.3 92.3
2 15.2 — 324.5 339.7
1 25.3 — 319.3 344.6
1/2 48.5 — 22.3 70.8
* 6 1/8% interest — 20 years planning period
** low solids handling rate used ($193/ton)
*** no sewer cleaning assumed
75
-------
The results depicted in Table 33 indicate that bi-
annual catchbasin cleaning in Boston is extremely cost—
effective. These results are somewhat biased in that average
catchbasin volumes in Boston are much higher than the
national average (see Table 31).
Case
In the prior example no wet weather control of
combined sewage other than WWTP control was considered. In
this example overall solids removal costs of catchbasin
cleaning are compared with the cost—effective results of a
recently adopted (1981) CSO Facll ity Plan in Saginaw, Michigan
(13). The new Facility Plan consists of extensive in—i i ne
storage coupled with bleedback to a secondary WWTP with ample
excess hydraulic and solids handling capacity and 5 maJor
swirl solids separator Installations to treat overflows.
Present worth cost (6 1/8% — 20 years) of the new in-
line storage program and the operational cost of soi Ida
handling at the City of Saginaw’s WWTP equals $2.26
million dollars. Annual elimination of wet weather related
solids and SOD loadings attributable to this plan equal 2.89
mu lion lb (1.31 mil lion kg) and 0.777 mil lion lb (0.353 rnil lion
kg), respectively. Overall present worth unit cost per pound
solids and BOD removed equal $0.0391 and $0.145,
respectively.
Combined present worth costs of the in—line storage
program, the five new swirl facil ities (less disinfection) and
operational costs of aol ida handling at WWTP equal $12.08
million dollars. Annual wet weather related solids and BOD
removed attributable to the combined plan equal 3.955
million lb (1.8 a 1111 on kg) and 0.907 mill Ion lb (0.412
million kg) respectively. Overall present worth unit cost per
lb solids and BOD removed equal $0.1527 and $0.656,
respectively. Costs for treating the detained combined sewage
volume at the WWTP are not included in either set of these
calcu I ati ons.
Overal I present worth aol Ida removal unit costs for
the 85 catchbasins in the West Roxbury test area equal
S0.0669/lb removed, $0.0659/lb removed and $0.0046/lb removed
for catchbasln cleaning frequencies of 2, I and 1/2 years,
respectively.These unit costs reflect the combined program
costs of catchbasin cleaning, sewer cleaning and WWTP
solids handling given in Table 32. it is clear that the
unit cost of solids removal attributable to a biannual
catchbasin cleaning program Is extremely cost—effective in
76
-------
comparison to either the In—line storage or in—line storage /
swirl solids separator treatment facilities.
Similarly, the unit cost of BOO removal attributable to bi-
annual catchbasin cleaning is cost effective in comparison to
either In—line storage or in—line storage/swirl treatment
assuming that the relative fraction of BOO to solids In
materials removed from catchbaslns is as low as 4%.
77
-------
REFERENCES &L BIBLIOGRAPHY
I. Lager, J.A., W. G. Smith and G. Tchobanoglous, “Catchbasin
Technology Overview and Assessment.” USEPA Report No.
EPA—600/2—77051, NTIS May, 1977.
2. Thomas, A.A., “Design Criteria for Storm Water Disposal,”
Fourth Annual Sanitary and Water Resources Engineering
Conference, June 4, 1965.
3. Foiwell, P.A., Sewerage , 8th ed., New York, Wiley, 928.
4. Babbitt, H.E., Sewerage Sewage Treatment , 6th ed.,
New York, Wiley, 1947.
5. Metcalf & Eddy, Inc., Wastewater Engineering: Collection
Treatment D-isposai , New York, McGraw—Hill, 1972.
6. American Pubi Ic Works Association. Survey of Practice as to:
Street Cleaning, Catchbasin Cleaning, Snow and Ice
Control, March, 1973.
7. Mahan, R.D., “Flow Characteristics of a Catch Basin. M.S.
Thesis, University of IllinoIs. 1949.
8. Water Pollution Aspects of Urban Runoff. American Public
Works Association. USEPA Report No. IIO3DNSCI/69
(NTIS PB 25 532). January, 1969.
9. Sartor, J.D. and G.B. Boyd, Water Pollution Aspects of
Street Surface Contaminants. USEPA Report No.
EPA—R27208 1 (NTIS PB 214 408). November, 1972.
10. Standard Methods for the Examination of Water and Wastewater
14th Edition, 1975 APHA—AWWA—WPCF.
11. Oceanography international Corp. E.P.A. approved Alternative
Method Federal Register Vol. 43, No. 45, TUOS., March 7,
1978.
12. Sewerage System Inspection Management Study.
Environmental Design & Planning, Inc. Draft Final
Report submitted to Boston Water & Sewer Commission,
Boston, Mass. February, 1981.
13. Pisano, W.C. et al., “Facil ity Plan For the Control and
Treatment of Combined Sewer Overflows to the Saginaw
River.” U.S. EPA report. Great Lakes National Program
Office, Cnicago, ill., March 1981.
78
------- |