Appendix 1. Highway Storm water Runoff Characteristics
Discussion
325
The American Public Works Association
1 recently has completed a report (2) for the Chicago
metropolitan area. Four types of field studies were conducted. These were:
1. Amount of salt and chromium in gutters and sewers following snow and ice control operations.
2. Amount, nature, and chemical and bacteria characteristics of street litter.
3. Effectiveness of street cleaning operations.
4. Role of catch basins.
Salt concentrations averaging about 14,000 mg/1 in the runoff from an urban expressway in
Chicago were found. It appeared that there was almost complete salt recovery; that is, all the salt
applied appeared in the runoff water. Hexavalent chromium in amounts as high as 116 mg/1 was found
in gutter water where a rust preventive chemical has been added to the salt.
From street litter sampling it was determined that the average daily accumulation of components
of Chicago street litter was from 0.5 to 8.0 lb/day/100 ft. (0.2 to 3.6 kg/day/30.5 m) of curb. Of this
amount, 0.4 to 5.2 lb/day/100 ft. (0.18 to 2.4 kg/day/30.5m) of curb was in the form of dust and
dirt-defined as material passing an 1/8-inc. (0.32-cm) hardware cloth. This material was determined to
be in the component of street litter which readily would cause chemical and bacteriological pollution
due to contact with and actual discharge with stormwater runoff from such littered gutter areas.
The weighted average, by land use, of the amount of dust and dirt, was 1.5 lb/day/100 ft. (0.7
kg/day/30.5m) of curb. The weighted average of commonly recognized pollution constituents was: per
gram of dry material, BOD-5,000 mg/1, COD-40,000 mg/1; nitrogen forms as N-480 mg/1; phosphate as
P04-less than 50 mg/1; total bacteria counts greater than 10 million; coliforms MPN - more than 1
million; and fecal enterococci - 5,400.
To what extent is this related to a standard population equivalent of 0.17 lb. (0.077 kg)
BOD/day/person? For a city the size of Chicago there are about 500 persons per mile of street. With a
dust and dirt accumulation of 1.5 lb/day/100 ft. (0.7 kg/day/30.5 m) of curb and a BOD of 5,000
mg/1 for the dust and dirt, there would be 0.8 lb (0.36 kg)/day/BOD accumulated/mile of street. This
amounts to about one percent of the raw sanitary wastewater from the abutting property or five
percent of the BOD discharged from secondary treated sanitary wastewater.
However, streets are not cleaned daily and there can be a considerable amount of litter on the
street at the time of precipitation. If it is assumed that there is a 14-day accumulation and that the
chemical and bacteriological pollution will go into solution within 2 hour, the relative amount of BOD
discharged as compared to sanitary wastewater discharged during the same period would be 160
percent, or 800 percent if compared to the secondary treated wastewater effluent.
Stormwater discharges cause a shock loading effect on receiving waters which vary with the
amount of dust and dirt, the amount of precipitation, the nature of the receiving body, and whether
the flow is in a separate or combined sewer. Stormwater in a combined sewer will resuspend previously
shoaled material.
An evaluation of street cleaning equipment indicates that conventionally-used equipment operating
on typical street surfaces is relatively inefficient in removing the dust and dirt fraction of street litter.
To effect a "clean" street in terms of reducing water pollution, improved equipment appears to be
necessary.
REFERENCES
1. ("The Causes and Remedies of Water Pollution from Surface Drainage of Urban Areas." Amer.
Pub. Works Assn. rept., U.S. Dept. Interior, FWPCA, Unpublished (1968).)
B. Petrelius, Sweden
To reconstruct combined sewers to separate ones is not worth the money. For a small part of it we
will be able to achieve about the same effect, or at least 90% of what a total reconstruction of a
combined system into a separate one would cost. Many Swedish cities have already or will in a few
years have sewage treatment works with a primary and secondary and tertiary treatment chemical
precipitation. Thus, stormwater runoff from separate systems will be of more and more importance,
relatively, and must be treated.
C. Gold, USA
Is BOD significant by comparison with stormwater runoff? In Newark, N.J., "first flush"
phenomena are quite pronounced, with high BOD, SS and chlorides from ice melting operations in
winter.
C. Truchot, France
What is the minimum treatment required before stormwater can be admitted into streams used for
recreational purposes?
Discussion
325
The American Public Works Association
1 recently has completed a report (2) for the Chicago
metropolitan area. Four types of field studies were conducted. These were:
1. Amount of salt and chromium in gutters and sewers following snow and ice control operations.
2. Amount, nature, and chemical and bacteria characteristics of street litter.
3. Effectiveness of street cleaning operations.
4. Role of catch basins.
Salt concentrations averaging about 14,000 mg/1 in the runoff from an urban expressway in
Chicago were found. It appeared that there was almost complete salt recovery; that is, all the salt
applied appeared in the runoff water. Hexavalent chromium in amounts as high as 116 mg/1 was found
in gutter water where a rust preventive chemical has been added to the salt.
From street litter sampling it was determined that the average daily accumulation of components
of Chicago street litter was from 0.5 to 8.0 lb/day/100 ft. (0.2 to 3.6 kg/day/30.5 m) of curb. Of this
amount, 0.4 to 5.2 lb/day/100 ft. (0.18 to 2.4 kg/day/30.5m) of curb was in the form of dust and
dirt-defined as material passing an 1/8-inc. (0.32-cm) hardware cloth. This material was determined to
be in the component of street litter which readily would cause chemical and bacteriological pollution
due to contact with and actual discharge with stormwater runoff from such littered gutter areas.
The weighted average, by land use, of the amount of dust and dirt, was 1.5 lb/day/100 ft. (0.7
kg/day/30.5m) of curb. The weighted average of commonly recognized pollution constituents was: per
gram of dry material, BOD-5,000 mg/1, COD-40,000 mg/1; nitrogen forms as N-480 mg/1; phosphate as
P04-less than 50 mg/1; total bacteria counts greater than 10 million; coliforms MPN - more than 1
million; and fecal enterococci - 5,400.
To what extent is this related to a standard population equivalent of 0.17 lb. (0.077 kg)
BOD/day/person? For a city the size of Chicago there are about 500 persons per mile of street. With a
dust and dirt accumulation of 1.5 lb/day/100 ft. (0.7 kg/day/30.5 m) of curb and a BOD of 5,000
mg/1 for the dust and dirt, there would be 0.8 lb (0.36 kg)/day/BOD accumulated/mile of street. This
amounts to about one percent of the raw sanitary wastewater from the abutting property or five
percent of the BOD discharged from secondary treated sanitary wastewater.
However, streets are not cleaned daily and there can be a considerable amount of litter on the
street at the time of precipitation. If it is assumed that there is a 14-day accumulation and that the
chemical and bacteriological pollution will go into solution within 2 hour, the relative amount of BOD
discharged as compared to sanitary wastewater discharged during the same period would be 160
percent, or 800 percent if compared to the secondary treated wastewater effluent.
Stormwater discharges cause a shock loading effect on receiving waters which vary with the
amount of dust and dirt, the amount of precipitation, the nature of the receiving body, and whether
the flow is in a separate or combined sewer. Stormwater in a combined sewer will resuspend previously
shoaled material.
An evaluation of street cleaning equipment indicates that conventionally-used equipment operating
on typical street surfaces is relatively inefficient in removing the dust and dirt fraction of street litter.
To effect a "clean" street in terms of reducing water pollution, improved equipment appears to be
necessary.
REFERENCES
1. ("The Causes and Remedies of Water Pollution from Surface Drainage of Urban Areas." Amer.
Pub. Works Assn. rept., U.S. Dept. Interior, FWPCA, Unpublished (1968).)
B. Petrelius, Sweden
To reconstruct combined sewers to separate ones is not worth the money. For a small part of it we
will be able to achieve about the same effect, or at least 90% of what a total reconstruction of a
combined system into a separate one would cost. Many Swedish cities have already or will in a few
years have sewage treatment works with a primary and secondary and tertiary treatment chemical
precipitation. Thus, stormwater runoff from separate systems will be of more and more importance,
relatively, and must be treated.
C. Gold, USA
Is BOD significant by comparison with stormwater runoff? In Newark, N.J., "first flush"
phenomena are quite pronounced, with high BOD, SS and chlorides from ice melting operations in
winter.
C. Truchot, France
What is the minimum treatment required before stormwater can be admitted into streams used for
recreational purposes?