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when you grade more than the land can bare?

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A thought that has been on my mind for a while tossed out for comments:

Grading and building practices in a multi-jurisdictional geological formation (a hill) prone to slides and hillside failures. And realistic approaches to successful long term development in just that kind of area.

In the southern area of Los Angeles there is a rather large hill that predominates a peninsula (Palos Verdes - spanning from Redondo Beach to the Los Angeles Harbor - San Pedro). It is about 1800 feet above sea level at the top and has a predominate soil content of bentonite clay. When wet, the soil behaves just like axle grease. It is slippery like nothing else in soil could ever aspire to. Over the last almost 50 years there have been development porjects that required extensive grading in the various municipalities (5) and unincorporated county areas (1). Virtually all of the larger ones have resulted in creation of landslide areas that make further building a somewhat mute point. Whole hillsides have failed massively, compromising areas of elevation near to 1000 feet over a couple of miles. As a result of some, nearly a hundred homes (or more) have been lost and razed. They were all custom and very expensive 50 years ago taking a good chunk of a gated community developed by the Vanderlip family.

First one was started by the County of Los Angeles in the Portuguese Bend area (now in the city of Rancho Palos Verdes). It ate, and continues to eat homes. The geologically doomed land is a construction moratorium area with numerous restrictions on everything including landscaping and irrigation. Water is the main source of problems. The soil expands and contracts creating slippage zones akin to how varying moistures in snow layers create avalanches. They were doing a road grade back in 1956 for Crenshaw Blvd. Every month or so, the county is forced to repair the road along the ocean there. They cannot abandon the road because it provides vital emergency services access to the backside of the peninsula as sole thoroughfare. Its like a topsy turvey whipped ribbon that almost wiggles as you watch. Movement is both lateral and vertical. Twenty and thirty foot grade changes in 60 feet are not uncommon, both up and then down and back. You can't build guardrails fast enough to keep up with the safety issues on a residence. Watching home owners try to keep their homes on their lots and habitable is an structural /civil engineers delight.

A couple of blocks from where I live there is a fenced off area on the bluffs (most southern point in Los Angeles in Point Fermin) referred to as Sunken City .

There are other three slide areas and then the capper of all landslides:
1) from Paseo Del Mar in front of a friends mom's house that ate the road that went thru, now a cul de sac at the border of RPV and PVE.
2) Bluff Cove. From the early 60's. Road Removal, 6 houses lost, city forced to buy the rest of the remaining residences on the cliff, a lawsuit, a 10% municipal utility tax to pay the people back who lost their residences. Basically a former city mayor (J. Barnett) spent more money with attorneys to push aside the problem of leaking storm drains undermining the whole hillside (45 + degree grade with about a 900 foot height in a single unabated slope). Eventually, they did fix the storm drains............ a little late.
3) Malaga Cove, chunks of cliff cracking away every time it gets wet. Great for mud skiing in a wet suit when you go down to surf - booties recommended. Fun Fun Fun!!

4) the $$$$$$$$$$ capper and planning caper as far as I can figure. There was a golf course development - 18 holes surrounded by large lots for multimillion dollar mansions a mile south of the original Portuguese Bend slide. Project is called "Ocean Trails." Referred to by many as "Motion Trails". Well, somehow they found a geologist (the second one) to sign off on the project. City, RPV was enthusiastic about big bucks developing the pristine chaparrel. They graded and graded and then graded some more. Then they did what they restricted just one mile to the north............. watered, and watered and watered some more. There were also water features (lakes with fountains). Obviously not enough plastic lining layer, but on a nice morning 4 holes roared down to the ocean and disappeared in about 8 seconds. Some local man was walking his dog and had the ride of his life. He lived. Walking the generous unbuilt homesites, there are cracks that disappear into the ground on virtually every lot. The golf course site wrapped an existing condominium developement from the late 60's that is a model (my opinion) of great site planning and integration. These people are totally at their wits end no doubt.

The developer declared bankruptcy before dawn the next day. The geologist is ....... well, not doing that professionally any more. Someone had the biggest drilling crane in the world out there trying to pin the hillside back into bedrock for about a year. Donald Trumpf is now the new deep pockets owner. Additionally, all the runoff full of pesticides has killed all the marine flora below the golfcourse (DDT round 2 polluting the PV peninsula waters).

That sums up the scenario.

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Personally, I think an observant and inquisitive 4 year old flying as a passenger in a small plane over the single geological formation referred to locally as "THE hill" could have told anyone you don't grade and water unless you want a monumental hillside failure. The problem seems to lie in the fact that there are 6 municipalities in the area. Each has its own financial interest in large scale developments, infrastructure, community amenities and bottom line - property values/tax base. They ignore what is in their own backyard. They have all engaged in planning strategies that ignored a huge problem, and sought comfortable old off the shelf approaches. Therein lies the problem.

But I think that people should be allowed to build, but..... if you do it in an area that is just a mess the whole process should be reevaluated and redefined. Build a house that will be self levelling on massive i beams if necessary. Pin it to the bedrock. Limit grading and work within certain limitations of cubic yards related to slope and patterns of natural drainage and erosion.

But the bottom line is that there is some formula probably based on existing grading permits over the last 50 years that could predict how much can be done without destroying what was buildable before the guys with big boy tonka trucks showed up.

Anybody know of any studies done in a similar area for maybe a doctoral dissertation by a geologist or civil engineer or a municipality study? Its something well past due around here. I heard rumour of a study done by the city of RPV that they buried because they did not want the news out about 20 years ago. Two of those commissioned geologists are now deceased - only one remaining. All the city officials are obviously different in all the municipalities affected. People forget and then do really dumb things in the interest of a buck. Maybe I should do a freedom of information act request......... They would not be amused or cooperative.

e-)

any ideas?
I grew up around the area on both sides of the hill. Its fun to watch the land have a life all its own.
 

Cardinal

Cyburbian
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art-tech geek said:
on a nice morning 4 holes roared down to the ocean and disappeared in about 8 seconds. Some local man was walking his dog and had the ride of his life. He lived.
What about the dog?

This is a lot like building on the seashore. Developers should have to prove that it is sound. OUr community would not accept a statement from the developers geologist. It would be verified by our own consultant at the developer's expense. Even so, if the development were allowed to occur, they should require a statement on the plat (and in every deed) to the effect that the buyer is aware of the potential danger of unstable ground and assumes all risk. The city should not be held liable, or be required to make any improvements at public expense to stabilize the area.
 
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