ATTENTION: Darwin Myers, Project Planner
RE: THE GARRITY CREEK PROJECT SD 01 8533

Dear Mr. Myers:
Site SD 01 8533 in its natural, native, park-like setting is ideal for an El Sobrante Valley park.  However, it is totally unsuitable for a Development of 41 homes and excavating  soil subject to liquefaction may cause the homes along Marin Road to slip and slide.  The planned steep hillside development is the same soil composite as the soil that is in Hilltop Green and they are having slide problems. (Hilltop Green Homeowners’ president Shirley Petty’s letter dated Jan 22, 2002). Homes in Aspen Court, adjacent and in the same Canyon as SD 01 8533, have had foundation and drainage problems. SD 01 8533 is  the same soil composite as the homes that slid on Pebble Drive some years ago and were subsequently demolished.  It is the same type soil as the slip area that came down on the hillside above Rancho Liquor store as a result of a  new home Development. It is the same soil composite as the large slide that caused part of Highway 80 to cave in. It is the same soil composite as the site where 2 homes were red tagged and 8 homes damaged on La Colina, and two dozen homes and roadways damaged on La Cima.  It is my understanding that a woman died as the result of damage on La Cima.  The roads and pillars shoring up the creek banks on Stanley Lane, a recent development by Mr. Afshar, have numerous cracks in the roadway adjacent to the Creek, and the pillars installed to protect the this area are leaning.  Are the pillars in danger of coming completely down?
 
 
The AMSO consulting engineers report of April 2001 on SD 01 8533 states that only 10 bore holes were made going down to a depth of 10 feet, some at 15 or so feet, and 2 at 20 feet.  They state they are assuming bedrock at 24 feet.  No bedrock was found at any of the elevations. How can they assume?  Why didn’t they go down another 4 feet and make sure that bedrock is present?  The report states that “Under the influence of severe ground shaking, the loose and saturated  layers of sands and silty sand that underlie the site will liquefy,” (4) and, it goes on to report “The property is underlain  by the Orinda formation bedrock consisting of severely weathered, highly fractured, clay stone and sandstone with lesser amounts of siltstone.  It could commonly be broken apart by hand”(3).  They also say that “the site revealed an apparent, minor slope failure within the westerly parcel.  This arch-shaped depression appears to be shallow within head scarp of about 3 feet and is about 30 feet wide.”(3).  They really hedge by saying they  couldn’t see it all.  The site was measured by a member of our Hilltop Neighborhood  Association, and he found it to be 90 feet wide and 200 feet long.  The attached pictures and drawings back up our findings. Residents have observed a slide three times as large as the slide area stated in the report, and have observed slides in more than the one area.   The Highway 80 slide area was a substantial number of feet deeper than was estimated and cost at least twice the amount of the estimate.
 
Our concern is that because they are making cuts and stripping all vegetation from building sites and proposed paved roadways (page 6 of AMSO Report), and they are buttressing against another hillside, the impact on the homes on Marin Road could be highly destructive.  Parcel 3, below Marin, is a 4 to 1 ratio.  If this project is allowed to proceed as stated then a substantial bond should be put up that would cover the cost of damage to homes on Marin Road and include the cost of potential clean-up.  What will folks on Marin do if down the road their houses are damaged by a slide and the Developer is bankrupt?  In this County,  other Developers have gone bankrupt. Also, another bond should be posted to insure that the riparian areas, trees, etc. are restored. A recommendation in the LSA Biology report, page 20, references a 5-year monitoring period and the need to cover 80% at the end of 10 years.  Other mitigation items are spelled out on pages 18 through 23 of the LSA report.

Another concern is that the AMSO report stated no ground water was found during any of the bore hole drilling.  Homes on Loma Linda and Manor have wells that are fairly shallow and have water year-round.  There is a known spring on the land and the plans are calling for a culvert to go from the site of one of the homes to the creek.  I find it strange that the report says no ground water was found from any of the bore holes.

The drainage system that appears to be in draft form is a concern of the Hilltop Green Homeowners Association.  Shirley Petty, president, in a letter written to you and dated January 21, 2002, addressed the flooding/drainage problems in Hilltop Green.  She also said she had a Soil/Geotechnical  Report completed.  Their data indicates that the Hilltop site lies at or near an area associated with shallow, intermediate and deep landsliding, soil erosion and creep.  The Hilltop Green site as you know, is adjacent to SD 01 8533. If the drainage is going into the storm system at Hilltop Green what will be the impact?  Loma Linda floods currently and Hilltop Green has flooding problems now.  Obviously our Association members are very concerned over the impact.

Again I want to mention that cut and fill areas in the AMSO Report call for a 2-1/2 to 1 ratio while the plans were drawn at 2 to 1 ratio.  I know you said the plans were a mistake.  How many other mistakes are there?

AMSO Consulting Engineering, in their report,  state they will only back up the conclusions in the report if they are the ones hired to review, observe, test and advise during the critical part of grading, etc. (pages 12 and 13 of the Report). Is the project so risky and the report so limited that it can’t be handled by another company from the AMSO specifications?

 
I also want to comment on the Klemetson Engineering letter to you and Mr. Drake on July 21, 2001, responding to questions on SD 101 8533. In that letter, Item 1, they state that the location of the surface slip area is a shallow slip and will be removed.  A bore hole wasn’t taken in that area.  Bore Hole 2 is above it and Bore Hole 3 below it, so the assumption of a shallow slip is unsubstantiated.  Item 3, variances and exceptions, according to Supervisor John Gioia’s knowledge the County hasn’t allowed variances on any projects. The County should not allow variances and exceptions on this project and why would the Developer ask for them on this project when he should be aware that the policy of the County is not to allow any variances.

            Item 4 is a vague description of the type of retaining walls to be built.  The walls below Marin Road would have to be substantial to prevent the sliding of houses on Marin.  Some retaining walls are going to be greater than 4 feet. What type of heavy duty retaining walls are being proposed? Item 5 of the Report states that the West Placer Sewer District has indicated that individual home pumping systems are acceptable.  Shouldn’t the Sewer District in El Sobrante be the ones to comment on the sewer system?

Item 6 is a complete evade-the-issue statement.  Quote: “Some retaining walls may be constructed to improve slopes.”  How can this statement be made when at the top of page 2 they mention retaining walls for 18 home sites with some 4 feet high or higher and, their statement that this subdivision is going to improve the slopes is unsubstantiated.  In fact, the opposite is really true.   Hilltop Green and all the other slides are a living example of the problems to be faced by placing homes on this unstable soil.

Item 8, a 1990 year Drainage Report, was prepared for Garrity Creek. This report is old and doesn’t begin to address the current problems added by the new homes built in the area since that time. Why is it even attached? The project that the 1990 report refers to wasn’t ever implemented. Why wasn’t it? Did the Developer go bankrupt or did the Developer find the soil too unstable and too costly to continue?

Item 9, an arch culvert bridge, should be approved by the Regional Water Quality Control Board.  The creek area is going to be ruined by culverts.

Copies of letters attached to the Klemetson Engineering Report are dated nine years ago and refer to a 1990 site plan, 12 years old, and before the Federal law of a 100 foot set-back from a waterway.  Why would they attach an out-of-date letter?  This entire Klemetson Engineering letter looks like it was written by someone trying to placate legitimate questions without doing their homework or research.

In conclusion, I urge you to declare this site unsuitable for development.  I urge you to assist us in acquiring the land for a Park for current and future generations to enjoy.  I urge you to assist us in preserving the site for the native animals, birds and the natural riparian habitat with the foliage and trees to support the native population.

 Sincerely,
 
 

BARBARA A. PENDERGRASS
Friends of Garrity Creek
Hilltop Neighborhood Association
745 Renfrew Road
 
El Sobrante, CA 94803

Attachments:
* Pictures of one of the slip areas on SD 01 8533.
* Drawing showing the actual size of the large slip.
 

cc:       John Gioia, Supervisor
           Robert Drake, Contra Costa County Community Development
Robert Kobchik, Contra Costa County Community Development
Shirley Petty, Hilltop Green Homeowners Association
Christine Boschen, Regional Water Quality Control Board
Nicole Kozicki, Fish and Game
Mitch Avalon, Contra Costa County Public Works
Dean Eckerman, Contra Costa County Public Works
Skip Hepplery, Contra Costa County Public Works
Nancy E. Stein, Contra Costa County Public Works
Kathleen Fudge, Contra Costa County Public Works
Barry Wilson, City of Richmond
Sharon West, City of Richmond
Lisa Viani, Urban Creek Council
Don Bastin, R9 Chair
Martha Borthelsen, Aquatic Outreach Institute
Eleanor Loynd, El Sobrante Valley Planning & Zoning Advisory Council
Terrance Cheung, District One Coordinator