Sukajaya Lempasing is one of the villages located in Teluk Pandan District, Pesawaran Regency, Lampung Province. Sukajaya Lempasing Village was chosen as a place for research because of its position on the east coast which is directly adjacent to Lampung Bay, of which its groundwater is suspected to be contaminated by seawater, causing the water to be brackish. Field observation, data collection, as well as lithology and air control are needed to see the geological and hydrogeological conditions of this area. Based on the physical and chemical parameters, the well of Hamlet 7 has groundwater and there is no indication of sea water intrusion because the area is very close to hills which may become a catchment area so that groundwater flows out to sea with high pressure. Based on the salinity, TDS, and conductivity values ​​obtained, the well that experienced seawater intrusion was the AJR3 well because it is located closest to the coastline and is supported by an alluvial sediment aquifer that has moderate to high aquifer productivity. The quality of water based on physical parameter data from wells in Hamlet 1, Hamlet 7 and sample AJR4 Hamlet 3 is classified as clean and suitable for daily use. The lithology in the form of alluvial deposits allows seawater intrusion, especially in areas close to the shoreline such as the AJR3 well.

Infrastructure development such as buildings, especially in multi-story buildings, really requires strong foundation support. In the construction of a multi-story building, usually using a pile that is embedded into a zone that has a hard rock arrangement or bedrock to support the building above it. This is a challenge for multistory buildings in areas of volcanic deposits or pyroclastic deposits. The rock layer below the surface in this area is dominated by less dense rocks such as tuff. This rock layer has more challenging when using for building foundations because it tends to be permeable, so a special method is needed to obtain information on hard rock or bedrock for building foundation needs. In other hand, the presence of weak zones, below the surface can cause sudden land subsidence which of course will damage the buildings on it. This study aims to determine the depth of the bedrock zone, in the pyroclastic deposit area using the integration of geophysical methods, resistivity and electromagnetic (EM) method. The resistivity method is more sensitive for areas that have large types of resistance or areas that are resistive, such as rocks that have low porosity and permeability such as igneous rocks. Meanwhile, the EM method is more sensitive in layers that have high porosity and permeability values or in conductive areas such as sediment layers. Nevertheless, the conductor layer is also influenced by the mineral content in the rock, so a good understanding of geology is needed in matching the data and conditions in the field. This is expected to be a reference in designing building structures, especially in pyroclastic deposit.

Lampung Bay is an area with a busy shipping traffic from port of Panjang and port of Teluk Betung. There are several river contain sediments and sedimented in Teluk Betung area. By conducting a research in this area, we can determine the sediment depositional system. The research method that will be used is the analysis of sediment deposition profiles from core data and interpretation from Ground Penetrating Radar (GPR). From sedimentary analysis, older sediments have a clay to coarse sand with relatively firm contact with coarsening upward patterns. In the top, they have a medium to clay with a fining upward pattern. The existence of a relatively thick clay layer indicates a relatively marginal depositional environment. These clay layers may form in the lower subtidal environment and gradually change to the upper intertidal environment until supratidal. This can be seen from the GPR result which show the sediment boundary. The GPR profiles confirm that the upper part mostly contains the sand or clay sand with sea water intrusion which has high conductivity and dielectric permittivity . The deeper zone could not well interpreted due to lack of the sediment information, but they show the contact of the sediment layers with different amplitude.