HomeMy WebLinkAboutMINUTES - 04011986 - 2.1 Jv
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THE BOARD OF SUPERVISORS OF CONTRA COSTA COUNTY, CALIFORNIA
DATE: Apr i'1 1, 1986
MATTER OF RECORD
SUBJECT: Vine Hill Road Detention Basin
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During the Board's consideration of a report relating to a proposed
amendment or alternative plans for the Vine Hill Road detention basin, the
following persons spoke:
1. Ellie Bellis, 2870 Vine Hill Road, Oakley, 94561; and
2. Pauline Elcenko, 2850 Vine Hill Road, Oakley 94561.
Ms. Ellis also presented to the Board a petition signed by approximately
50 residents of. the area, requesting the elimination of the Vine Hill Detention
Basin before the next rainy season.
THIS IS A MATTER FOR RECORD PURPOSES ONLY
NOEXMM ALT 1ON TAKEN
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TO: BOARD OF SUPERVISORS
FROM: J. MICHAEL WALFORD, CHIEF ENGINEER
DATE:. April 1 , 1986
SUBJECT: Amendment of Drainage Plan for Drainage Area 29H, Oakley
Specific Request s , or Recommendations & Background & Justification
RECOMMENDED ACTION:
As the governing board of the Contra Costa County Flood Control and Water Conservation District:
1. ACCEPT the report from the Chief Engineer outlining alternative plans for the elimination
of the Vine Hill Road detention basin site from the Drainage Area 29H plan; and
2. SET June 10, 1986, at 10:30 a.m, as the time for a public hearing on the amendment of
the Drainage Area 29H plan.
FINANCIAL IMPACT:
None
REASONS FOR RECOMMENDATION/BACKGROUND:
The proposed Engineer's Report is attached. The June 10, 1986, hearing date is necessary
to provide time for the completion of environmental documents and the required legal notice
for a public hearing on the proposed amendment.
Continued on attachment: yes Signature: '✓ �
Recommendation of County Administrator Recommen ion of Board Committee.
Approve Other:
Signature(s):
Action of Board on:' April 1, 1986 Approved as Recommended x Other
Also ACCENTED report from the Chief Engineer of the Flood Control District on
Interim solutions for the Vine Hill Road Basin problem; and. REFERRED the question of
funding to the Finance Committee for review prior to the June 10, 1986 hearing.
Vote of Supervisors f I HEREBY CERTIFY THAT THIS IS A TRUE
AND CORRECT COPY OF AN ACTION TAKEN
x Unanimous (Ab'sent — ) AND ENTERED ON THE MINUTES OF THE
Ayes: Noes: BOARD OF SUPERVISORS ON DATE SHOWN.
Absent: Abstain:
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BO:vine.t3 4 Attested
Orig. Div.: Public Works Dept. (FCE) Phi Batchelor
cc: County Administrator Clerk of the Board of
County Counsel Supervisors and County
Community Development. Director . Administrator.
Chief Engineer
FCE File: 3029-29H-00
DEPUTY
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ENGINEER'S REPORT
ON
ALTERNATIVE DRAINAGE SOLUTIONS FOR LINE A
IN DRAINAGE AREA 29H, OAKLEY AREA
General
Line A is part of the approved plan of Drainage Area 29H in the Oakley Area. It
drains the westerly half of the Drainage Area 29H watershed. The Line A system
consists of pipe lines and drainage detention basins. One of them, at Vine Hill Road,
is considered undesirable. This report discusses alternative plans and their ramifi-
cations for amending the adopted plan to eliminate the Vine Hill Road basin site.
Line A of the Approved Plan
Line A consists of two holding basins, one located at Vine Hill Road and the other
between State Highway 4 and the AT & SF Railroad, and pipe lines ranging in size from
18 inches to 72 inches in diameter. The estimated 1985 cost of the drainage system
for the entire drainage area was $4,933,000 resulting in a drainage fee of $0.27 per
square foot of impervious surface.
The Alternatives
Alternative 1 : Relocate the basin from Vine Hill Road approximately 1 ,300 feet
northerly along Line A to the north of Oakley Road. This necessi-
tates an increase in the size of the pipe between the old and new
basin locations, but allows a decrease in pipe size between the .
new basin and the one at the AT & SF Railroad. The basin at the
Railroad may be slightly decreased in size. The estimated total
cost is .$4,997 ,000 for the revised drainage system in the entire
drainage area. If distributed to all properties, it results in a
drainage fee of $0.28 per square foot of impervious surface.
Alternative 2 : Delete the basin at Vine Hill Road entirely and enlarge the basin
at the AT & SF Railroad. The drainage pipes between Vine Hill
Road and this basin will have to be significantly larger than
those for the approved plan and Alternative 1. The basin at the
Railroad would also require an increase of approximately 60
percent in size. The estimated cost for the drainage system in the
entire drainage area is $5 ,336,000, resulting in a drainage fee of
$0.29 per square foot of impervious surface.
Alternative 3 : The same as Alternative 2 except that, rather than increasing the
basin at the AT & SF Railroad, the outlet pipes draining the basin
to the river are increased in size. The estimated cost for
incorporating this alternative in the drainage system for the
entire drainage area is $5 ,442,000, resulting in a drainage fee of
$0.30 per square foot of impervious surface.
Alternative 4: Delete all detention basins from Line A. Carry the drainage by a
pipe system and inlets from Vine Hill Road to the river. This
alternative requires the largest pipes. The estimated cost for
the drainage system for the entire drainage area is $6,060,000,
resulting in a drainage fee of $0.33 per square foot of impervious
surface.
Discussion of Alternatives
Alternatives 1 through 4 represent cost increases of $64,000; $403,000; $509,000; and
$1,127,000, respectively, when compared to the approved plan. All cost figures are
based on 1985 prices.
We recommend Alternative 1 , as the most suitable. The cost increase is minimal . As a
result a plan amendment, based on this alternative, could be implemented without a fee
increase. We are aware of a tentative proposal to form an Assessment District including
part of the easterly half of the drainage area. This would not affect any of the
proposed alternatives. However, Alternative No. 1 is more compatible with the assess-
ment district option in that it permits rerouting of the basin discharge to the east.
We favor detention basins over straight=through pipe lines because; 1) a system based
on detention basins is more economical , 2) the capacity of a detention basin can be more
readily increased than pipe systems to accommodate drainage from urbanization in
excess of the anticipated levels.
Recommendation
We recommend that the Board of Supervisors:
1. Select Alternative No. 1 as the basis for the amendment of the Drainage Area
29H Plan, and
2. Retain the present drainage fee ordinance for Drainage Area 29H.
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CONTRA COSTA COUNTY FLOOD CONTROL AND WATER CONSERVATION DISTRICT
255 GLACIER DRIVE, MARTINEZ, CALIFORNIA
DATE: March 31 , 1986
TO: Board of Supervisors
FROM: J. Michael Walford, Chief Enginee r �
SUBJECT: Report on Interim Solutions for Vine Hill Road Basin Problem
OUR FILE: 3029-29H-00
In response to the Board' s direction, we have outlined in this memo five potential interim
solutions for the elimination of storm waters from the Vine Hill Road infiltration basin in
Drainage Area 29H.
OPTION 1 :
Allow the existing basin site to operate, with necessary protective measures, until the
selection and .construction of alternative drainage facilities. This option would still
entail the costs 'of securing the area during ponding, i .e. , the erection and removal of
barricades and yellow warning cordon, estimated at $3,800 per year.
OPTION 2:
Improve the infiltration capacity of the existing site by scarification or the drilling of
wells (casings above ground level ) through which water could dissipate faster. The approxi-
mate cost of scarification would be $1 ,500/year, the drilled wells would add a minimum
initial outlay of $8, 000. The cost- of security, since the infiltration would be slower
than the discharge into the basin, would be additional .
OPTION 3:
Water collected in the existing basin could be pumped via a temporary. line uphill to the
existing infiltration basin at Stirrup Drive. Apart from the doubtful legality of this
option, it would also overload and possibly destroy the currently well-operating basin.
The installation cost would be approximately $7,000, the annual cost of operation and basin
security would be about $6,500.
OPTION 4:
Acquire and prepare an alternate site (e.g. , Alternative No. 1 of the Engineer'.s Report `on
Alternative Solutions for Line A in DA 29H, Oakley Area) and pump the water there from the
current basin. Assuming that the alternate site is acceptable, the approximate cost for
the preparation of the new basin site, installation of the pumping system and lines would be
$336,000, the 0 & M costs would be $5 ,500/year, including security at the current basin.
OPTION 5:
Acquire and construct the alternate basin site and install the connecting gravity drain
from the current site. This would, for all practical purposes, eliminate the current
ponding problem. Surface drainage in the current basin area would still have to be
collected. The cost of the permanent installation would be $550,000.
It should be noted that Options 1 through 4 would still allow intermittent ponding at the
current site. Further, the implementation of Options 4 and 5 are conditional on the new
site having a good infiltration capacity. Until the construction of permanent improve-
ments, including Option 5, the current ponding problem will remain.
FUNDING
The purpose of the formation of Drainage Area 29H in June of 1983 was to provide for the
installation of drainage infrastructure in the watershed. The fee system does not provide
for unusual maintenance or operational expenses.
Drainage Area 29H currently has sufficient funds for the purchase of the new basin site
required by Options 4 and 5. It does not have enough funds for the installation of the
permanent gravitydrain to it.
Drainage Area 290 was formed in 1977 for the purpose of minimal maintenance of interim
infiltration basins. The interest earned by the funds collected by Drainage Area 290
amount to about $900/year; maintenance expenses are charged against it. .
The funds of Drainage Area 290 are neither adequate, nor were they meant for the construction
of temporary installations such as pumping systems and drain lines. Without Special
District augmentation funds, Drainage Area 290 could not be depended on for financing any
of the above options.
The following funding sources could be considered:
A. Assessment district,. to be imposed upon those directly benefitting from the improve-
ments, to fund any of the above options beyond the normal obligations of existing
flood control entities,
B. Benefit assessment area, subject to majority vote within the tributary-area, for the
original and' annual costs of the option chosen,
C. Special funding from sources as yet unidentified.
TIMING
Subject to the availability of funds, Options 1 , 2, or 3 could be ready to operate for the
winter of 1986.
Option 4 is subject to the acceptability, acquisition, and excavation of the new basin
site. The drainage area plan must be amended prior to the acquisition of the property.
This option could not be operational. at least until the winter of 1987.
Option 5 , due to 'its high initial costs, may not be available for a number of years.
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