An oedometer test on a clay soil gave the following results: Cc = 0.4, Ce = 0.08, OCR = 5. The thickness of the clay layer in the field is 2.6 m. The existing vertical effective stress at the mid-depth of the clay layer is 150 kPa. This vertical effective stress will increase to 350 kPa due to the load imposed by a building foundation. Calculate the primary consolidation settlement. If the OCR was 2 instead of 5, what would be the difference in primary consolidation settlement?