SB 1090: Senate Sub-Commitee Voting Recap
SB 1090: Senate Sub-Commitee Voting Recap
Dr. Pat Davis & Charlie McDermott’s Senate Briefing and Senate Testimony-May 26, 2020
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By, Charlie McDermott
It is a big deal that SB 1090 didn’t get killed. And Surfrider has committed that they hate SB 1090 because of seawalls and lack of sand. SB 1090 can make a lot of progress without new seawall language. The most objective science driven doc is the Army Corp Report for our area:
Overview of the Current Situation.U.S. Army Corps of Engineers Environmental Impact Report
Overview of the Current Situation
My house is not in danger (I just moved to the beach recently) but some simple fixes would greatly benefit the public and ocean front home owners want help fund putting sand on the beach.
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There have been many studies in our area and each lot has its own soil report so there is a ton of data is out there.
I found the Army Corp report on the sand replenishment project for our area to be the most easy to read and very comprehensive.
Here is the link to the ACOE plan and all supporting documentation: U.S. Army Corps of Engineers Environmental Impact Report
All of the approaches for erosion mitigation in SB 1090 have been utilized all around here so there is no novelty being introduced by the bill in terms of the technology.
The general idea is that by using notch infills to fill up sea caves or toes to support eroding bluff bases we can greatly mitigate sudden collapses; especially when there is a sand deficit and cave formations. The materials for all these patches are known and defined and (when done right) will blend in with the bluff face.
For max safety you need a seawall or significant sand and notch fills.
The area where the Davis family tragedy occurred (is referred to herein as Reach 1 (p. 13)) and the main beach for the area (Beacons Beach (Reach 2)) are excluded from sand replenishment. I will try to find out why these major areas were excluded (P 102) because sand flows generally North to South. The public really thinks these key areas will be getting sand.
The 1.1 mile section of Reach #1 (equivalent to 130 lots; if each were 50 feet wide, i.e., Grandview to past Beacons) deposits a total of 1,100 cubic yards of sand onto the beach each year or 8.4 cubic yards per year per 50 foot section.
The $25,000 sand offset permit fee can buy around 1,000 yards of sand. And these offsets are supposed to cover the life of the potential beach loss for 20 years. So work that triggers such a sand offset fee permit will put about (1,000cu-yd)/(8.4cu-yd) = 118 years of sand offset on the beach for a 50 foot wide lot.
To put 1,000 cubic yards in perspective; that would be a 10 foot high pile of sand 50 feet wide that extends 60 feet out onto the beach or a football field about 6 inches deep.
The Army Corps looked at all scenarios debated today and included sea level rise (page 53) analysis. The initial report must have been written a few years back because the La Jolla tidal gauge (page 53) inset stops at 2010. The good news is that we are holding around the long term trend see: NOAA Relative Sea Level Trend San Diego, California
Fun fact, 1983 recorded a 30 foot at 16 seconds wave height (P58) and they proposed a great reef design for surfing (p 109); this would be a very very popular add in.
We are currently in the “No Action Alternative” (page 96); i.e., the sand is gone and the deficit is not yet replaced.
So in the case of Reach 1 and 2 and similar situations the least complex and intrusive option with the most safety benefit (aside from seawalls) are notch / cave infills (see page 116 and 118). This is described in “Notchfill Only” (p 111).
This photo is an excellent cut away that shows that the bluff face is in fact not solid and uniform but it is vertical slabs. And when even a few feet of the base are are cut away they can fall forward.
Lifeguard tower photo: The Grandview stairs are protected by a notch infill (on the right) and over time you can see the subtle difference at the base of the bluff face base. On the left a few feet are cut away and on the right it is a vertical face with no base erosion. This base erosion looks like no big deal but it undermined the support for the upper part and it fell forward where the Davis family were while the lifeguard tower was in no danger just a few yards north. Even in person the right and the left of the tower look the same and the stairs installation is quite old.
This photo is about an 8 foot high bluff face right near the public beach access at Grandview with a cave that badly needs a fill of any kind. Kids like to play in here and the one just a few lots over clamped shut. Once this is filled and the ice plant removed from the edge you get a much safer spot.
Regards,