PORT WORKS DESIGN MANUAL PART 3 Guide To - The University ...

34appropriate, deposition of the sand blanket and installation of band drains.For areas in the vicinity of proposed seawalls, placement of fill should notcommence until completion of the seawall foundation.• Stockpiling of fill - The reclamation sequence should be carefully planned tomake sure that the programmes of seabed preparation and seawall constructionare compatible with the intake rate of fill. Stockpiling must not be allowedwhere it might cause failure, for instance, close to recently constructed seawallsor the edge of the reclamation.• Site supervision - Stringent control should be exercised on the placement of fillin thin layers, particularly on the initial layers. Fill placement in shallowwater onto thick marine mud is very vulnerable to mud wave formation.Stability at each interim construction stage should be checked.3.2.2 Long-term Stability of Drained ReclamationSince reclamation is ultimately enclosed by seawalls, the long-term stability of a reclamationdepends on whether the seawalls are capable of retaining the fill. Guidance on designrelated to the stability of seawalls is given in Part 4 of the Manual - Guide to Design ofSeawalls and Breakwaters.3.3 Dredged ReclamationThe principles and methods for analyzing the stability of a dredged reclamation are in generalthe same as those of the drained reclamation.Since the soft, compressible sub-soils such asmarine mud or clayey alluvium deposits are removed, the stability during construction isnormally less critical than that of a drained reclamation.However, if there are existingstructures or developments adjacent to the reclamation site, the stability of the temporaryslopes of the dredged surface should be checked to ensure that the factor of safety is adequate(see Section 3.2.1).For the long-term stability of seawalls enclosing a dredged reclamation, Part 4 of theManual - Guide to Design of Seawalls and Breakwaters should be referred to.