Mini dredgers proposed for city’s clogged drainage channels – Dutch report
As a result of a reduction in the cross-sectional flow of water in the areas of many of the drainage channels in Georgetown, the Dutch Risk Reduction (DRR) team of experts have recommended the procurement of minidredges to fix the problem.
The DRR team in a report stated that although the sources of the deposited sediments have not been examined, it is likely that much of the sediments enter the drainage system from “the roads, illegal deposits, discharges and construction activities.”
Deposited sediments must be removed regularly in order to maintain the passage capacity of the system and the common way to remove it is by an excavator that operates from the landside. But this has proven to be a problem because most places have buildings and human activities occurring.
Thus it was proposed that a good way to maintain the city’s drainage channel at locations where excavation from the landside is not possible would be by floating minidredges, such as cutter suction dredges.
The report stated that in The Netherlands, as well as in many other countries, these minidredges are often used to dredge channels in highly urbanised areas or in situations where mud needs to be removed.
The report also indicated that in some instances, a floating pipeline is used to pump the dredged sediments or water mixture to a location where it can be further processed.
“If such minidredges become available these may also be used to maintain the outfall channels. This would require the minidredges to be easily transportable, especially across the streets,” the report added.
But, nevertheless the DRR team highlighted that before a minidredge is purchased, it first needs to be determined if such an investment will be profitable. This assessment starts with the computation of the potential benefits of dredging channels that currently cannot be maintained.
The report added that the benefits of dredging are the expected reduction in flood damages, for which different flood scenarios, each with its own percentage of occurrence, need to be considered. The expectation is that dredging results in a lowering of the flood risk.
It was also asserted that this benefit should be compared with the costs for purchasing, maintaining and operating the minidredges.
Based on this data, a business case can be developed and a sound decision can be made on required dredging capacity, the report said.
According to the report, decisions should be made on whether a public or private entity will run the city’s dredging operations. Afterward, it stated, a request for proposal to purchase dedicated equipment should also be made.
The Government of Guyana has requested the Government of The Netherlands to provide advice on its drainage situation, both for Georgetown and the low-lying agricultural coastlands. The official request from the Guyanese Ministry of Public Infrastructure was sent to The Netherlands Embassy in Suriname in 2015.