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 SHORE COLLECTION SYSTEM
Section 3.
2.3.1 PIER SEWERS. Installation of sewage collection systems is underway
on most piers and quay walls where CHT equipped ships berth routinely. The
system consists of a pier sewer line, pier risers with quick disconnect
couplings for making ship-to-shore connections, and a pump station for dis-
charging the waste into the shore activity sewerage system.
2.3.2 GRAVITY COLLECTION SYSTEMS. Some of the first pier sewer collection
systems constructed were designed for gravity flow. This resulted in rather
large collection lines to accommodate the flow rates from the ships' pumps.
These large gravity lines proved unsatisfactory because:
a. In many cases, it was difficult, if not impossible, to install the
large lines under the piers.
b. The investment costs were high because of the installation and pro-
curement costs for the larger pipes.
In addition to the above, an operational problem with the gravity sys-
tems has been noted. The high flow rate from the ships' pumps has caused
the sewage transfer hose to pulsate. This condition has caused the hose to
chafe on the edges of the pier and, on some occasions, has led to failure of
the hose. This phenomenon will be discussed in detail in Chapter 8, Section
2.5.
2.3.3 PARTIAL PRESSURE COLLECTION SYSTEM. In order to limit the excessive
peak flow rates and control the size of the pipelines, a "partial pressure"
system has been developed. The system consists of a gravity sewer main down
the center of the pier and pressure manifolds centered on each berth (see
Figure 2-3). The standard pressure manifolds consist of 4-inch pipe headers
running parallel to the pier face with a single 4-inch connection to the
gravity sewer. Four single or double receiving connections are provided at
150-foot intervals along the length of the manifold. Each manifold is
designed to receive sewage from one ship or from a nest of ships at a par-
ticular berth (see Figure 2-4). The small-diameter pressure pipe serves to
throttle the ship's pumps, thereby reducing the flow rate to the gravity
sewer.
2.3.4 PIER SEWER CONNECTION FACILITIES.
Two types of connection facilities
are provided with the collection system.
a. Connections above the Pier Deck. For this type of facility,
exposed receiving hose connections are installed approximately 18 inches to
2 feet above the pier deck. The connections are located inside the pier
curbing and are protected against damage by a concrete or pipe rail enclo-
sure. Concrete barriers form a box, and the outer wall of the box serves as
the pier curb. A drainage grate is provided within the box in case of
spills. Figure 2-5 illustrates a pier sewage riser protected by a pipe rail
barrier.
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