The design engineer or the engineer's authorized representative shall:

(1) Conduct inspections to:

(a) Verify LOSS construction and materials conform with approved plans and specifications; and

(b) Collect data for the record drawings.

(2) Inspect the following:

(a) Poured-in-place sewage tanks construction;

(b) Installation of proprietary and public domain treatment and dispersal components;

(c) Installation of LOSS components in difficult conditions including, but not limited to, steep slopes and shallow soils; and

(d) Placement of sand or other fill material.

(3) Conduct or witness LOSS component testing to verify that all results fall within acceptable limits:

(a) Water tightness testing of all tanks under WAC 246-272B-05200; and

(b) Pressure testing of all new collection and conveyance piping according to an acceptable industry standard; and either

(c) Pressure and flow testing of the subsurface drip system to verify it functions properly prior to scheduling a LOSS final inspection by the department; or

(d) Pressure testing of the drainfield to verify it functions properly prior to scheduling a LOSS final inspection by the department.

(4) Record baseline pressure and flow information and provide passing results to the department during the final inspection.