Basic HTML Version
SOP3 – Sampling Protocol
21
4.0 SOP 3 - Ballast System Sampling Protocol
Version: 2.0
Date of Issuance: June 29, 2012
Author: George Smith
4.1.
Overview
Continuous, time-integrated, isokinetic sampling (as describe in ETV Protocols) occurs at a fixed
rate during uptake and discharge. Two sampling assemblies reside in a modified, bow-mounted
20-foot shipping container with garage-doors, lights, outlets, and other alterations. One sampling
assembly is dedicated to each tank and pump/pipe array. Sample flow is available in every
ballast-operation mode. Pressure at sample-points is similar to pump-discharge pressure except
post-vendor which may be up to 6 or -7psi lower. Ballast system operator will maintain sample-
point pressure sufficient for sampling rates of between 3 m
3
h
-1
and 10 m
3
h
-1
without need for
additional sampling pumps. Sampling rates are monitored via precise magnetic flow-meters
(Liquid-Controls) logging their data to the IMAC process-control system. Rate adjustments
occur via Hayward diaphragm valves allowing fine-grain adjustments. The >50 µm biota fraction
are removed from sampling flow via 35 µm square-pore water-suspended net-collectors. Nets
must receive visual inspection before every use and the inspection is to be noted on the system
hygiene QAQC sheet. Continuous (time-integrated) sampling occurs during uptake or discharge
of water from the tanks, as required by ETV and IMO protocol. Wastewater from this process is
directed to overboard drains. Whole-water samples (not sieved) are taken for the 10 µm to 50 µm
biota and water quality assays. They also are time-integrated.
4.2.
Start-up
Sample from the pipes/pumps assembly is delivered to sampling assemblies by 1.5” smooth-bore
hoses stored in the sampling structure. They attach at the pump and pipes assembly and the
sampling assemblies via cam-loc fittings. Hoses must receive 2-minute sample flush prior to
sample collection, and 5-minute potable-water flush following sample collection. Sample flush is
performed in sea-to-sea mode on uptake, and during a brief (1 minute) pre-sampling period of
recirculation on discharge. Water-suspension barrels for the >50 µm sample collectors are filled
during sea-to-sea prior to uptake and during recirculation prior to discharge. One barrel per
assembly receives collector-sieved water for use in net/collector wash-down and live-sample
analysis. The pre-discharge recirculation mode may entrain rust and other debris from the pipes.
This may make it advisable to wait to fill collection barrels until the ballast system has been
sample-rinsed (voiding the rust) and temporarily switched back to recirculation holding pattern.
This issue does not occur on uptake.
4.3.
Sampling Rates
Ballast sample departs the pump and pipes assembly at pitot-tube sampling ports installed
before/after treatment bypasses. Pitot-tubes avoid sampling flow edge in the main ballast pipe, as
would occur with a simple ‘tee’, and they maintain comparable flow-vectors across transition
from ballast-pipe to sampling system. Volume required to be removed from the ballast pipe for
vector maintenance at the pitot-tube is dictated by flow-rate and flow-velocity in ballast-pipe.
Typically, the volume removed is more than samples require. Therefore, a portion is diverted and
drained overboard from sample assemblies. Table 4.1 showing ballast-flow, sampling, and dump
rates as posted in the sampling area is referenced in order to set specified sampling and dump