In a report to the Ministry of Planning and Investment, they said the port in the eponymous district requires 571 ha of land and 481 ha of water surface.
The land includes 83 ha now covered by natural mangrove forests, they admitted.
In January the city had proposed construction of Vietnam's largest port at a cost of US$5.45 billion.
According to the plan proposed by container shipping company MSC, it would span over seven kilometers in length and be capable of berthing the heaviest container ships available today (at 250,000 DWT).
It would be built on Phu Loi Islet of Thanh An Island in the Cai Mep Estuary in seven phases, with the first to be completed in 2027 and the last in 2045.
HCMC said the port would be a boon to the local and national economies, contributing VND34-40 trillion in the form of taxes and fees to the government's coffers annually once completed in 2045.
It would also create 6,000-8,000 jobs directly and tens of thousands of others indirectly for people working in logistics.
The volume of goods passing through HCMC ports is expected to increase by over 5% on average until 2030, and the number of containers by 6%.
In the preliminary environmental impact assessment of the project, the city-based Portcoast Consultant Corporation said its only "sensitive" aspect is the use of the protective forest.
But it added this could be resolved by amending the purpose of its use from forest land to construction land.
Besides, the project would be planned with a green tree ratio of more than 10%, it said.