Basic HTML Version
SOP1 – Ballast Operations
10
A blocking valve is not required for pump start-up in recirculation-mode. Start pump and run in
recirculation to create flow for prepping the sample skid and/or vendor should vendor treat
discharge. Determine/ coordinate timing of any vendor activity such as UV chamber or chlorine
neutralization treatment in the advance operations meeting that morning.
Prior to sampling treated discharge or priming the sampling system briefly discharge tank-2
overboard for 1-minute as insurance against unintended items entering the samples. To do this
open flow to overboard via overboard ‘block’-valve, then, close the valve in the recirculation
path nearest overboard ‘block’ valve just opened. Discharge for 1 minute while adjusting
pressure/flow to targets, then either immediately initiate sampling or if not ready to sample/treat,
switch back to recirculation until ready. Do not discharge for more than 1-minute without
sampling. Sampling protocol is provided in SOP 4.
Closely observe flows, pressures, and tank-level during discharge. If discharging at high flow-
rate (>250-m
3
h
-1
) observe when tank-levels drop under 0.3-m and to preclude pump cut-out via
air-induction/whirl-pool at the tank inlet reduce flow to 250 m
3
h
-1
. When tank-levels drop below
0.2 m, flow should be reduced to around 200 m
3
h
-1
. Such flow adjustments may require minor
sampling rate adjustments to maintain sample-volume targets. Once levels fall below 0.4 m, you
may open the lower-tank-hatch for observation. Pump will entrain air (suck-dry, lose prime)
when tank is empty and this can be noted by change in the pump’s sound. If not immediately
stopped via control input, the pump sense ‘dry-run’ in several seconds and stop on its own.
Close valves associated only with treated pump/tank system #2 forward), including secondary
tank-isolation. Repeat the operation for control tank (#1 aft). A short break is acceptable. You
may end the event and start a new one for the next tank. Paper-record any needed parameters off
the IMAC or they will become unavailable once the event is stopped, that is until the data are
transferred to file-maker (see SOP 4 detailing instrumentation).
2.7. Ballast System Cleaning and Shutdown after Discharge
Following completion of a discharge event prepare pipes for rest by flushing/draining as
previously described for uptake. However, this time all valves without exception are left partly
(butterfly-valves) or fully (bottom-drain-valves) open on completion of the flush/drain
procedure. Turn off power to VFDs.
Tanks will be hosed out and pressure washed with municipal potable water. Open primary tank
isolation valves and aft trunk-drains. Leave forward trunk drains closed for now. Attach
overboard hoses to the aft trunk drains. Thoroughly pressure-wash all surfaces. Wear
appropriate protective clothing and hearing protection. All traces of sediment must be flushed
out staining/water-lines are to be absent on completion of the wash-job. Expect to spend in the
region of an hour or more per tank on this chore. A shop-vac is available to remove mud from
the drainage trough although it may be washed down the grate as well. Last work-item on
cleaning the pipes after discharge involves flushing the trunk lines that run below the tanks.
Remove overboard drain hoses from the aft trunk drains and attach potable water adapter hose
from aft drain to potable water manifold. Turn on water and let run out forwards trunk drains for
10-minutes each. Water should run clear and clean after the first few minutes. Leave bottom
drains open.