The proposal is to place sand (surcharge) to a height of 4.5 metres along a 1.9 kilometre length of the Mitchell Freeway adjacent to Lake Monger. The sand is to be piled to consolidate peat and an old sanitary landfill site for works associated with the widening of the Mitchell Freeway and the provision of a median strip for the proposed Northern Suburbs Rail Link.

Because of the presence of peat and sanitary landfill, the ground is relatively spongy and would create an unsuitable base for the freeway and the rail link without treatment.

Included in the proposal for surcharging are six options for the landscaping and redevelopment of a section of the Lake Monger foreshore affected by the freeway widening proposal. Main Roads' preferred option for this facet of the proposal involves filling approximately 9,000 square metres of the lake including the creation of an island for tortoise breeding purposes. It is then proposed to landscape and revegetate the filled area, including the translocation of existing reed beds and the planting of native vegetation to create wildlife habitat. The existing path (dual use path) that circumnavigates the lake will be maintained at all times during the project.