From NAVFAC DM-7.2 (as background):
If a wall is prevented from even slight movement, then the earth remains at or near the value of at-rest conditions. The coefficient of earth pressure at-rest, Ko, for normally consolidated cohesive or granular soils is approximately:
Ko, = 1-sin [theta]'
where: [theta]' = effective friction angle
Thus for [theta]' = 30 degrees, Ko, = 0.5.
For over-consolidated soils and compacted soils the range of Ko, may be on the order of 1.0. In cohesionless soils, full at-rest pressure will occur only with the most rigidly supported wall. In highly plastic clays, soil may creep, and if wall movement is prevented, at-rest conditions may redevelop even after active pressures are established.
Basement and Other Below Grade Walls. Pressure on walls below grade may be computed based on restraining conditions that prevail, type of backfill, and the amount of compaction.
EFFECT OF CONSTRUCTION PROCEDURES.
Staged Construction. As earth pressures are influenced by wall movement, it is important to consider each stage of construction, especially with regard to brace placement and its effects.
Compaction. Compaction of backfill in a confined wedge behind the wall tends to increase horizontal pressures beyond those represented by active or at-rest values. For guidance on horizontal pressure computations associated with the compaction of granular soil, see Figure 13 (after
Reference 7, Retaining Wall Performance During Backfilling, by Ingold).
Clays and other fine-grained soils, as well as granular soils, with considerable amount of clay and silt (>/=15%) are not normally used as backfill material. Where they must be used, the earth pressure should be calculated on the basis of "at-rest" conditions or higher pressure with due
consideration to potential poor drainage conditions, swelling, and frost action.
You should contact the geotech of record for the original soils report and ask them to provide specific guidance based on your specific situation. You may end up paying for their review, but the peace of mind could be worth it.