Info

15,200

235,000

<1%

<1%

Total wasted

8,327,500

4,577,000

23,887,400

19,129,000

15,986,000

5,563,000

48,210,090

29,269,000

100%

100%

Notes: aIncludes 200,000 tn of flyash bAt San Diego, 4700 tn of vessel garbage at $280,000 dumped in 1968 (discontinued in November 1968).

cTonnage on wet basis. Assuming average 4.5% dry solids, this amount is about 200,000 tn/yr. of dry solids being barged to sea. dRadioactive waste omitted because sea-disposal operations were terminated in 1967.

Notes: aIncludes 200,000 tn of flyash bAt San Diego, 4700 tn of vessel garbage at $280,000 dumped in 1968 (discontinued in November 1968).

cTonnage on wet basis. Assuming average 4.5% dry solids, this amount is about 200,000 tn/yr. of dry solids being barged to sea. dRadioactive waste omitted because sea-disposal operations were terminated in 1967.

at a depth of 320 ft on the edge of a submarine canyon. Later, Los Angeles mixed some of its sludge with sawdust and sold it as compost.

In designing outfalls in the ocean, environmental engineers try to achieve good mixing between the heavier saltwater and the lighter sewage effluent. Good mixing is essential to ensure that the waste does not surface like an oil slick and pollute the shoreline and beaches. Environmental engineers can use the following equation in designing an outfall:

where:

N = The maximum tolerable shore pollution expressed as the arithmetic mean or 80 percentile Q = The average sludge flow

Y = The depth at which the sludge is discharged into the ocean

X = The distance of the discharge point from the shore K = A constant that varies from 5 to 10 million, when the units are in feet and gallons

Another method of disposing sludge and municipal solid waste is ocean landfills. Hong Kong has built marine fills for disposing its refuse in the estuaries of the bay. The marine fill is surrounded by a solid rock dyke, and refuse is loaded and compacted into it. Tidal action causes some leaching of the marine fill. After about 3 years, the refuse converts into compost and is used on nearby farms.

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