336
D.H. Waller
Table 4 shows the capital cost implications of four schemes that this community can
use if it wishes to reduce wet-weather pollution discharges. Solids and BOD loadings are
based on Figs. 1 and 2. The solids and BOD loads removed are net loads, i.e., they have
been corrected to allow for increased dry-weather discharges from the treatment plant
resulting from flows returned from the retention basin. It is assumed that the community
must incur the cost of a dry-weather treatment plant (2 MGD), and costs per unit of
pollutant removed per year are based on costs and wet-weather removals in excess of
those associated with that plant. It is evident that in the situation described by this
illustration the retention basin-treatment plant system is the most efficient scheme in
terms of total removals and in terms of capital cost per unit of pollutant removed.
CONCLUSIONS
The information and the illustrations that are presented herein lead to the following
conclusions:
1. Combined sewage is a significant pollution source.
2. Urban surface runoff is the major source of combined sewer solids, and may be a
significant source of pollution when discharged untreated from a separate sewerage system
3. A retention basin-sewage treatment plant system offers an effective and an
economical method of providing treatment for wet-weather and dry-weather discharges
from a combined sewerage system.
ACKNOWLEDGEMENTS
Most of the study that is described herein was conducted by the Atlantic Industrial
Research Institute, Halifax, N.S., for Central Mortgage and Housing Corporation, Ottawa,
under a contract entitled "Pollution Due to Storm Water and Overflows from Combined
Sewers".
REFERENCES
1 BURM, R.J., KRAWCZYK, D.F. and HARLOW, G.L., "Chemical and Physical Comparison of
Combined and Separate Sewer Discharges", Jour. Water Poll Control Fed. 40, 112-126 (1968).
2 DOBBINS, W.E., "Frequency and Composition of Storm Sewage Overflows", Proc. Symp. on
Treatment of Storm Sewage Overflows, New York Univ., April (1962).
3 Engineering-Science, Inc., "Characterization and Treatment of Combined Sewer Overflows", Final
report to U.S. Fed. Water Poll. Control Admin., Nov. (1967).
4 ESCRITT, L.B., "A Re-Examination of the Storm Tank Problem", Water and Waste Treatment,
298-300, Sept./Oct. (1969).
5 MELPAR, "Combined Sewer Temporary Underwater Storage Facility", report to U.S. Fed. Water
Quality Admin., Oct. (1970).
6 Ontario Water Resources Commission, "Sewage Treatment Plant Construction Costs", Pub. No. 1,
Design Approvals Branch, OWRC (1967).
7 U.S. Department of Health Education and Welfare, Public Health Service, "Pollutional Effects of
Stormwater and Overflows from Combined Sewer Systems", Public Health Service Pub. No. 1246
(1964).
8 WALLER, D.H., "Combined Sewers in Canada", Engineering Journal 52, 6, 22-29 (1969).
9 WEIBEL, S.R., ANDERSON, R.J. and WOODWARD, R.L., "Urban Land Runoff as a Factor in
Stream Pollution". Jour. Water Poll. Control Fed, 36, 914-924 (1964).
D.H. Waller
Table 4 shows the capital cost implications of four schemes that this community can
use if it wishes to reduce wet-weather pollution discharges. Solids and BOD loadings are
based on Figs. 1 and 2. The solids and BOD loads removed are net loads, i.e., they have
been corrected to allow for increased dry-weather discharges from the treatment plant
resulting from flows returned from the retention basin. It is assumed that the community
must incur the cost of a dry-weather treatment plant (2 MGD), and costs per unit of
pollutant removed per year are based on costs and wet-weather removals in excess of
those associated with that plant. It is evident that in the situation described by this
illustration the retention basin-treatment plant system is the most efficient scheme in
terms of total removals and in terms of capital cost per unit of pollutant removed.
CONCLUSIONS
The information and the illustrations that are presented herein lead to the following
conclusions:
1. Combined sewage is a significant pollution source.
2. Urban surface runoff is the major source of combined sewer solids, and may be a
significant source of pollution when discharged untreated from a separate sewerage system
3. A retention basin-sewage treatment plant system offers an effective and an
economical method of providing treatment for wet-weather and dry-weather discharges
from a combined sewerage system.
ACKNOWLEDGEMENTS
Most of the study that is described herein was conducted by the Atlantic Industrial
Research Institute, Halifax, N.S., for Central Mortgage and Housing Corporation, Ottawa,
under a contract entitled "Pollution Due to Storm Water and Overflows from Combined
Sewers".
REFERENCES
1 BURM, R.J., KRAWCZYK, D.F. and HARLOW, G.L., "Chemical and Physical Comparison of
Combined and Separate Sewer Discharges", Jour. Water Poll Control Fed. 40, 112-126 (1968).
2 DOBBINS, W.E., "Frequency and Composition of Storm Sewage Overflows", Proc. Symp. on
Treatment of Storm Sewage Overflows, New York Univ., April (1962).
3 Engineering-Science, Inc., "Characterization and Treatment of Combined Sewer Overflows", Final
report to U.S. Fed. Water Poll. Control Admin., Nov. (1967).
4 ESCRITT, L.B., "A Re-Examination of the Storm Tank Problem", Water and Waste Treatment,
298-300, Sept./Oct. (1969).
5 MELPAR, "Combined Sewer Temporary Underwater Storage Facility", report to U.S. Fed. Water
Quality Admin., Oct. (1970).
6 Ontario Water Resources Commission, "Sewage Treatment Plant Construction Costs", Pub. No. 1,
Design Approvals Branch, OWRC (1967).
7 U.S. Department of Health Education and Welfare, Public Health Service, "Pollutional Effects of
Stormwater and Overflows from Combined Sewer Systems", Public Health Service Pub. No. 1246
(1964).
8 WALLER, D.H., "Combined Sewers in Canada", Engineering Journal 52, 6, 22-29 (1969).
9 WEIBEL, S.R., ANDERSON, R.J. and WOODWARD, R.L., "Urban Land Runoff as a Factor in
Stream Pollution". Jour. Water Poll. Control Fed, 36, 914-924 (1964).