Preliminar


minary


design of the LNG tterminal


gn of the erminal


To provide a basis for the design, ARCADIS first set up hydraulic models to determine wave conditions and currents along the entrance channel and in the area of the new terminal. Because the design should allow for possible future development into a port able to handle other commodities such as containers and/or bulk cargo, a master plan was prepared incorporating both the LNG terminal and space for future develop- ment. Based on the metocean conditions, different concepts were developed, also including two options for the access channel. To evaluate whether the preferred approach channel alignment (because lower maintenance dredging was expected) was feasible from a nautical point of view, some initial fast-time manoeuvring simulations were carried out.


The concepts were discussed and further optimised. As it is uncertain when the facilities for other commodities may be required, the LNG terminal from this selected layout was further detailed. And because only shelter for the FSRU and the LNG carrier are required, the breakwaters could be shortened significantly.


The preliminary design was extensively eval- uated and additional runs with the validated flow model were carried out to determine the effect of the terminal on the flow. Results were used to assess the expected sedimenta- tion in the port basin and access channel in


order to estimate the future dredging quanti- ties. Current and wave fields were also input s channel


dr dging quanti- s wer


into the design of the access channel. The required width was determined using the results of fast-time manoeuvring simulations for easterly and westerly going curr


ined using the vring simulations oing current


directions and a range of wind conditions. ind conditions


As a large part of the existing entrance channel to Montevideo can only be dredged to 13.5 m below mean sea level, the availa- bility of the channel was a major concern. Using the results of calculations of the vertical response of the sailing ship in combination with an extensive analysis of simultaneous data from wave and water level measurements, it could be demonstrated that the probability of bottom contact during channel passage was very low as high waves occur only in combination with increased water levels.


Other studies included time-domain simula- tions of moored ship response for the FSRU and LNGC at the terminal to evaluate avail- ability and vessel traffic simulations to assess the effect of the future traffic increase on the capacity of the access channel.


A nautical risk assessment study was also carried out. The probability of the LNGC grounding and collisions with other traffic were assessed and the effects of mitigating measures such as the implementation of a VTS system were quantified. Due to the


Sailed track of fast-time simulation for design of the entrance channel and risk of grounding


long channel, the risk of grounding was relatively high, but as the bottom and sides of the channel consist of mud, the risk of penetration of the LNG tanks is low.


This preliminary design was used in the successful tender for the installation and operation of the terminal, including the required port structures. The design has now been verified using full-mission simulations and dredging of the channel and the construction of the terminal is expected to start soon.


report 19


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