Can someone help me with this questions of materials and methods

Question

1. Geotechnical tests for a given site indicate loose sandy soils to a depth of 15 feet with mixed sandy loam extending an additional 10 feet to a porous limestone bedrock. Tidal data indicate rising levels of saline groundwater presenting within 3 feet of the grade (ground level). Make recommendations for foundation materials that are likely to contribute to the longevity of the structural foundation system. Identify the materials and the reasons for your selections.

Answer 1

Because shallow footings would rest on weak, liquefiable upper soils, the structure requires a deep foundation system—specifically Deep Driven Precast Concrete Piles or Cast-in-Place (CIP) Drilled Shafts / Augercast Piles extended past the sandy layers to embed directly into the competent limestone bedrock at ~25 feet.

I'd recommend Concrete specifically (HPC) Mix Design and waterproofing barriers. For reinforcement use epoxy-coated rebar(ASTM A775) or Dual-Coated Reber, any rebar that is immune to chloride corrosion and provides a physical barrier against salt exposure and is durable.