Cooperative program for the certification of interstate shellfish shippers.
- United States. Public Health Service. Division of Environmental Engineering and Food Protection
- Date:
- 1962
Licence: Public Domain Mark
Credit: Cooperative program for the certification of interstate shellfish shippers. Source: Wellcome Collection.
25/90 (page 17)
![(2) Total quantity of sewage which can be discharged from any given unit, or from a combination of units, without caus- ing the basic water quality standards to be exceeded. (3) Amount of shipping in the area and the amount of sewage which can be expected. Design criteria which may be useful in formulating an opinion on the quantity of sewage which can be discharged into an area without exceeding the desired water quality standards include: Population equivalent (coliform) of sewage; predicted survival of coliform in sea water, effectiveness of chlo- rination, and the total quantity of clean dilu- tion water in an area. Results of many studies on the survival of bacteria in sea water have been summarized in An Investi- gation of the Efficacy of Submarine Outfall Disposal of Sewage and Sludge; Publication No. 14, California State Water Pollution Control Board, 1956. The mechanical equipment at critical sew- age treatment or pumping units should be such that interruptions will be minimized. Wherever possible operations should be auto- matically recorded on charts. Examples of the requirements which might be imposed, depending upon the importance of the unit in terms of water quality, include: (1) Ample capacity for storm flows. (Storm water should ordinarily be excluded from the sanitary system.) (2) Standby equipment to insure that treatment or pumping will not be inter- rupted because of damage to a single unit or to power failure. (3) Instrumentation of pumps and equipment to allow the regulatory agency to determine that performance standards have been met. Examples include: (a) Recording scales to indicate rate of chlorine use. Chlorine flow can be in- tegrated with hydraulic flow to establish a ratio. (6) Liquid level recording gauges in overflow channels of sewage treatment plants and wet wells of lift stations to indicate when overflow takes place. Charts should be dated and initialed January 1959 by the operator. Gauges should be calibrated so that discharge can be estimated. (c) Automatic devices to warn of fail- ure or malfunctioning at self-operated pumping stations or treatment plants. (4) The effect of storm sewage can be calculated by multiplying the total esti- mated flow by the observed coliform con- tent. The result can be expressed in terms of population equivalents (coliform). Design and operation of equipment should be such that closure provisions should not have to be invoked more than once per year under ordinary circumstances. A closed safety area should be interposed between the conditionally approved area and the source of pollution. The size of such area should be based on the total time it would take for the operating agency to detect a failure, notify the State shellfish control agency, and for the latter agency to stop shell- fish harvesting. It is recommended that the area be of such size that the flow time through the safety area be at least twice that required for the notification process to become effec- tive. Due consideration should be given to the possibility that closure actions might be necessary on holidays or at night. The type of marking which will be required for conditionally approved areas will vary from State to State depending upon the legal requirements for closing an area. The length of time a conditionally approved area should be closed following a temporary closure will depend upon several] factors in- cluding the species of shellfish, water tem- perature, purification rates, presence of silt or other chemicals that might interfere with the physiological activity of the shellfish, and the degree of pollution of the area. (See sec- tion D-1 of this manual for additional] infor- mation on the natural purification of shellfish. ) 5. Restricted Areas.—An area may be clas- sified as restricted when a sanitary survey indicates a limited degree of pollution which would make it unsafe to harvest the shellfish for direct marketing. Alternatively the States may classify such areas as prohibited. (See section C-6, this manual.) Shellfish](https://iiif.wellcomecollection.org/image/b32177653_0025.jp2/full/800%2C/0/default.jpg)
