TANKS

steel or concrete (except that all-steel would be

needed for relocatable plants).

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Unless otherwise specified, all materials and equipment shall be new and be

standard commercial products in regular production by the manufacturer, and

suitable for the required service. The sewage treatment plant shall

include the following systems and components: A diffused air aeration

system [or mechanical aerator(s)] for the aeration tank and the aerobic

digester; [mechanical sludge collection equipment [(if used)] for the

settling tank]; froth control system for the aeration tank; sludge pumps in

the settling tank and the aerobic digester for sludge transfer; scum

removal system for the settling tank; [a comminutor at the plant inlet;] a

[chlorinator] [hypochlorinator] and all necessary piping. All structural

steel shall conform to ASTM A 36/A 36M. All submerged steel members shall

have minimum thickness of 6 mm 1/4 inch. [Reinforced concrete slab shall

be designed and constructed for all-steel treatment plant].

2.7

TANKS

2.7.1

General

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NOTE: Use appropriate wording depending on whether

plant is to be installed above ground (hydrostatic

pressures...liquid level) or below ground (soil

pressures...operating level).

The following factors should be considered in

determining whether plant will be aboveground (at

finished grade) or below ground (below finished

grade):

1. Gravity flow to plant is to be preferred; need

for pumping sewage to plant should be avoided.

2. Elevation should be such as to avoid flooding

from surface runoff.

3. Plant should be not less than 900 mm 3 feet

above water table.

4. Plant should be installed below ground in cold

locations to prevent freezing; however, concrete

plant offers somewhat more protection against

freezing than steel.

5.

Aesthetic considerations.

6.

Extremely aggressive soil conditions.

7. Initial cost savings resulting from aboveground

installation.

8. Projected relocation of plant.

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NOTE: Delete references to and requirements for

SECTION 11375N

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