Email Correspondences Received from Richard Moll (April – July 2005)
Richard Moll
Top Level Comparison of Alternatives
#2 Geomorphic
Basis: pure geomorphic stream pattern
Fatal flaw(s): (unrealistic design)
7/5/05
(1.) Channel does not match existing channel @ Edith Bridge.
(2.) Significant loss of Theis property (excessive encroachment unacceptable to residents)
(3.) Significant loss of Wittner property
(4.) Significant loss of Lippe property
(5.) Unacceptable destruction of trees.
(a.) Removal of “28 trees of particular value”.
(b.)
Removal of “43 trees to save if possible”.
(6.) Design not integrated with Robleda Storm Drain outflow.
(7.) Possible loss of Remmel property/residence.
#3 Modified Geomorphic with Step Pools
Basis: modify #2, straightening channel sinuosity
Fatal flaw(s):
(1.) As above.
(2.) Reduced channel capacity (low cfs).
(3.) As above.
(4.) As above; even more so.
(5.) As above.
(a.) Removal of “14 trees of particular value”.
(b.) Removal of “37 trees to save if possible”.
(6.) As above.
(8.) Possible significant loss of Remmel property & residence.
#4 Modified Geomorphic with Cascading Step Pools
Basis: modify #2 & #3, step pools all moved to below Wittner.
Fatal flaw(s):
(1.) As above.
(2.) Reduced channel capacity (low cfs).
(3.) As above (loss somewhat reduced).
(4.) As above.
(5.) As above, but fewer trees.
(c.) Removal o f “8 trees of particular value”.
(a.) Removal of “37 trees to save if possible”.
(6.) As above.
(7.) Step pools shown extending beyond top of bank on LAH side downstream of
Robleda storm drain outfall.
#5 Collaborative Blue line with Step Pools
Basis: modify #2 & #3, step pools all moved to below Wittner.
Fatal flaw(s):
(1.) As above.

(2.) Reduced channel capacity (low cfs).
(3.) Excessive hardscape (1525 sqm. Vs 788 now)
(almost double existing amount)
#6 Blue Line Geomorphic
Basis: maximum geomorphic features within the blue line easements; hardscape protection at critical corners.
Fatal flaw(s):
NONE
Potential design improvements
(1.) Increase channel width just upstream of Lippes and Robleda storm drain outflow to reduce hardscape requirements below estimated 900 sqm.
Alternatives Downstream of Robleda Storm Drain
"A" Necessary Bank Protection
Basis of concept: Patch only
Fatal flaw(s):
(1.) Does not address need to correct for and prevent further erosion at Robinwood Pool.
"B" Extra Rock Lining at Robinwood Pool
Basis of concept: Address erosion (past & future) at Robinwood Pool
Fatal flaw(s):
NONE
Potential design concerns/improvements:
(1.) Stacking rock rip rap at 1:1 slope high enough to provide 100 yr. protection
"C" (“D”) 125 (250) linear ft. vertical wall
Basis of concept: Use vertical concrete wall for erosion protection at pool site & Remmels (&
Lippe)
Fatal flaw(s):
(1.) Tall, large concrete wall was rejected by citizens 20 years ago.
6/9/05
Katherine, Tony, Saeid, et al.,
How steep can a bank of boulders be?
At our May 25 th meeting, Tony presented plans for the creek down below the pool that showed boulders stacked fairly high and steep. What is technically feasible and acceptable?
In Mitch Swanson’s report, he showed a bank at 1:1 slope on both sides of the creek at the Robinwood Pool/Moos property. His report text did not elaborate or clarify the construction, but I think that I remember his verbal comment that downstream of the
Robleda storm drain outfall, the building material would have to revert to gabion baskets because rocks could not be stacked that steeply.

Please advise.
Also, both the Swanson plan and the former District plan had hardscape on both sides of the creek from the storm drain to project end, reflecting the deep incision of the creek, the concave bank on the Moos side, the erosion patterns, the current geomorphic situation, and the flow profile of the creek. I am concerned that a district solution that does not acknowledge this existing reality is doomed to failure.
Richard Moll
May 18, 2005
SCVWD Design Team:
Dear Katherine, Saeid, Tony, et al
I am deeply concerned that the design for the creek down by Robinwood Pool is not getting enough love and attention. When I spoke to you all at the conclusion of our May 11 meeting at
Hillview, I tried to convey my concern. Here are a few points I wanted to put down on paper for your review.
1. I do not think the real life problems downstream of the storm drain have been comprehended or addressed in an overall or systematic manner. Such as: the Remmel waterfall; the gunnite along the Remmel bank cracking and being eroded behind at the pool property line; the height and scope of the concrete riprap at the center of the pool property, and the fact that the creek has undercut eroded the base of this riprap; the erosion at the pool -Van Horne property line; the impact of the Robleda storm drain outflow into the creek flow pattern; the fact that there is steel mesh fence in the creek holding brush cuttings to protect the Lippe property from further erosionat the Remmel -Lippe property line; the fact that the storm drain as installed had inadequate outflow protection, undercut the Moos bank and as a result a 60 to 80 ft tall tree was undermined and fell across the creek and would have cut the Remmel house in half except for the fact that it miraculously fell into a major fork in the Remmel's back yard tree, and that the subsequent extension of the rock splash apron may only be marginal.
2. The pool property is a legitimate residential building site, and should be considered to have a commensurate market value. Any creek design that would compromise it's value is unacceptable. Please acknowledge this situation: see my letter to SCVWD in March 2000 and
Jennie Micklo's response in Sept (sent under separate cover).

3. Last week after the meeting Tony showed me the profile of the design for downstream of the
Remmel waterfall, and said that the profile from the old design had just been taken for use. The bottom profile shown had THREE GIANT WEIRS of about SIX FOOT DROP each. What gives? How can you claim to be limiting the upper portion weirs to 10 to 14 inches, and then switch to 6 ft drops below the storm drain? This tells me that you have not given this any realistic thought. Plus what about fish passage over 6 ft drops? Who thought this would fly?
4. Tony did not comment of the street drain outfall on the Van Horne property; I may have been too upset to hear him even if he did.
5. The colored handout showing the hardscaped areas of the creek was wrong at the pool. The riprap, colored orange, extends all the way to the top of the riprap arch; it does not cut off on an angle at the oldest easement line as shown. A second easement was given in 1986 for those repairs, I believe. Also, the hardscape at the Remmel property is gunite, expending all the way to the pool property line, rather than a shorter wood wall as shown.
6. How is hardscape coverage computed? Is it only the projected square footage on a plan view? What about when the sides are vertical concrete, and the bottom is gravel? Is the vertical concrete ignored? Is that why we feel there should be more hardscape accounted for on the existing condition? Should there be a different category for vertical hardscape ? Also, much of the vertical board wall on the Los Altos Hills bank across from Levis has been eroded out? Was that ignored? Should it have counted? Also, what about the channel bottom that was concreted, but it too has been eroded out? Was it ignored? Should it have been counted?
7. I do not feel that there has been an integrated, systematic, hydraulically realistic assessment and practical evaluation of the intersection of the almost 60 degree turn in the creek direction at the Lippe property, the impact of the Robleda storm drain outflow, and the Remmel waterfall.
8. Almost every practical evaluation of the concrete wing wall at the Millar's property, extending immediately downstream of the bridge, acknowledges that keeping it intact and in place is the smart thing to do. This seemed like a surprise to several members of your team.
9. I was confused that the channel capacity just downstream of the bridge was the smallest in
Alternative Number 4. When Saeid tried to explain it, I got the impression that the 10 ft wide channel bottom required down near the storm drain was simply used as the width all the way up to the bridge, with the banks sloping shallower and shallower as the creek depth decreased as the bridge was approached.

This seems like an artificial restriction; make the damn creek deep enough to handle the water that is expected.
Also, the minimal creek depth that exists at the Seligman's was apparently not considered in setting the creek depth in that area.
10. There was no consideration given to the yet to be accounted for OVERLAND water flow, either through Astiz's back yard or down the swale between Astiz and Rogez. Not only as it enters the creek from the Los Altos Hills bank, but probably more importantly, if it forces the main flow in the creek away from the undisturbed flow, and starts to impact the Los Altos bank such that hardscape is required to prevent erosion and a change in the channel.
Furthermore, does such a side flow, even though for a relatively short time period, need to be considered in the geomorphic design of the channel and its curvature?
Thanks for reading this far. Richard Moll
May 8, 2005
Post Meeting comments by Richard Moll:
1.
Paul Lippe
We shouldn’t be spending time on alternatives that are unacceptable to the residents.
The alternatives were developed by the whole Collaborative, which includes the regulatory agencies and citizens in addition to the
Reach 5 residents in an open forum, and all of them need to be considered.
Richard commented later in reviewing the drawings that these four alternatives were developed by SCVWD, not the whole Collaborative. The 142concerns were developed by the Collaborative, but have not been imposed on these four alternatives.
2.
3.
Paul Lippe
District should model an alternative that doesn't remove any trees.
This was a major point made by Paul with heated exchange with Jitze. Paul was extremely adamant about starting with the objective of meeting “tree constraints”.
I’d always assumed that halfway down to the stormdrain, capacity wouldn’t have any affect on
Richard Moll what flows over the park. I now understand that downstream of the bridge, capacity will affect the flow over the park.
Sure. But at Robleda drain you’ll have the 1% capacity.

Richard Moll
You’re saying Alternative 4 only allow s 750 cfs
100 feet downstream of the bridge.
Right.
4.
I do not accept this argument. Show us data for backup and overflow in Reach 6 (for example, if the downstream could accept unlimited flow, or if the Reach 5 flow channel had only 10 cfs capacity).
Susan Mandle What is the capacity that the bridge can carry? 1200 to 1400 cfs
5.
Clarify existing (with sediment and sewer line) or what was design capacity?
Richard Moll
Repair sites downstream of the storm drain is unacceptable. Need to provide continuous protection from the Remmel property to the
Robinwood pool property. 5
The plan was to provide repair to exposed sections only.
This was also a major concern. All the focus was on before the storm drain and it seemed like only lipservice to lower portion. Also, no attention was given to profile considerations at the bridge, head cuts or Remmel dam as I requested in my letter to
Katherine 2-3 months ago.
February 19, 2005
BOUNDARY CONDITIONS for ADOBE CREEK DESIGN
As a result of Dr. Sen's Geomorphic Study presentation at the Feb. 9, 2005 Collaborative Meeting, some questions passed through my mind regarding the boundary conditions that need to be addressed and resolved with full disclosure to the Collaborative as we start this interesting phase of our discussions. Dr. Sen may have answered some during his presentation, but there was so much information that he was showing that was so new to most of us,
I felt that further documentation was appropriate.
1. What is the correct initial thalwag depth (elevation) to use at, near, or under the start of the project by the Edith
Ave Bridge?
a. from the '83 bridge design?
b. from the rejected '02 design?
c. at the upstream entrance to the bridge, under the bridge, or at the downstream exit from the bridge?
d. since the sewer line crossing was built after the '83 bridge design, and not considered in the rejected '02 design, and now forms the equivalent of an unintentional step with no pool, how should it be compensated for in the creek design?
e. none of the above.
2. What is the correct thalwag depth to use at the Robleda storm drain outlet?
a. the current thalwag depth is less than one foot below the S/D outfall pipe lower lip.
b. I think the rejected '02 design showed the thalwag several feet lower than the S/D pipe opening, with the pipe rerouted both horizontally and vertically.

c. what are the other options to select the correct thalwag depth with respect to the outfall pipe?
i) optimum outfall height?
ii) optimum outfall with respect to the bend in the creek?
iii) optimum outfall considering both the bend and the transistion to the lower downstream segment?
d. other, taking into consideration the entire design?
3. What is the correct thalwag depth to use at the end of the project, down by the Ward, Van Horn, and Moffat properties?
a. the current depth?
b. from the rejected '02 plan?
c. in consideration of the flow down to the new culvert under Foothill Expressway?
d. in consideration of minimum excavation, and using the current scoured channel as the excavated depth where possible for a cost effective solution? This might require a final step and pool as the end of the project.
e. in consideration of replacing the existing wooden walls on both sides of the creek.
f. other?
4. What are the implications of the incised depth of the existing channel with respect to overwhelming the geomorphic analysis for a natural, stable solution?
a. the existing incised depth severely limits the channel width downstream of the Robleda S/D outfall, especially at that bend and then downstream of the concrete drop headcut at the Remmel's property.
b. what is the channel wall design solution for downstream of the S/D?
c. how does it affect the upstream design?
d. where does the combination of existing (or projected )incised depth and the required width for a natural, stable geomorphic solution come into conflict? Is it upstream of the S/D outfall?
5. Between the Edith Ave Bridge and the storm drain: a. add the concrete wing wall coming downstream out of the bridge on the Millar side as a fixed constraint.
b. relate the locations of the two existing concreted headcut locations and the existing longitudinal profile to the locations of the proposed 7 steps, and resultant profile.
c. should the new step locations be evenly spaced, or is there rationale for their uneven location?
d. can initial steps angled crosswise to the stream flow help redirect flow towards the Los Altos Hills side and away from the redwood trees we are trying to save and protect? For example, steps immediately next to the bridge, or even underneath the bridge?
e. relate the proposed step location and profile to the existing bank height to look for problem overflow areas, such as the low bank at the Seligman (Wentz) property.

Written by Richard Moll, 13 Feb 2005