Pismo Beach officials say the seawall is necessary to protect the St. Andrews sewage pumping station, located 12 feet from the edge of the bluff on Seacliff Drive at Baker Avenue, near Memory Park in Shell Beach.
City officials are concerned that a large storm could cause the bluff to fail and damage the lift station, which raises sewage from a lower pipeline to a higher one.
After commissioners approved the plan in January, officials with the U.S. Army Corps of Engineers, which has worked with the city on the project and is footing much of the estimated $2.7 million construction cost, raised concerns about specific wording in two of the commissions conditions for the project.
The two agencies later agreed on some modified wording, which was approved at the commissions meeting in San Francisco.
City officials are now waiting to receive a partnership agreement with the Corps before construction can start, Community Development Director Jon Biggs said.
Construction could start in the early part of 2014 and could take about nine months, based on the citys experience with two other seawalls it built, Biggs said.
The commission has also required Pismo Beach return in five years to report on what steps it could take to relocate the sewage lift station. Community Development Director Jon Biggs told commissioners that work on a managed retreat study has already started.
Brad Snook, chair of the Surfrider Foundations San Luis Obispo County chapter, told commissioners that the group supports a timely relocation of the lift station.
In addition, the city is to provide an assessment of the seawall in 20 years, which the commissions executive director will use to determine whether the seawall is still needed and should be retained, removed or modified.
The Corps and the city have maintained that relocating the pumping station would be more expensive than building a seawall. In response to a Coastal Commission request, the Corps estimated that relocation would cost $3.5 million.