HomeMy WebLinkAboutAgenda Report - March 16, 1983 (39)Agenda item K-5 - "Determination of basin location in G
Drairnage Area" was introduced by City Manager Glaves.
Council had, at an earlier Informal Informational Meeting
(Shirtsleeve Session), reviewed the "G -Area Storm Drain
Basin Study" as prepared by the City of Lodi Public Works
Department.
The study evaluated two alternate storm drain basin/pipe
systems to serve the G -area. Alternate A consists of two
basins--C-north anA G -south, and Alternate B consists of one
larger basin located at the G -south site. The pipe systems
are similar except the main line between G -north and G -south
is substantially larger in Alternate B clue to the
elimination of G -north Basin.
The study procedure involved the following:
1) Determined basic engineering criteria and making various
assutptions or decisions to insure the eoftVarisions are
done on an equal basis.
2) Designing the alternate systems - basin size/depth and
pipe sizes.
3) Making cost estimates of the system excluding land
cXosts.
4) Determining total system cost versus variable land
costs.
5) Preparation of draft written report.
6) In-house technical review.
7) Outside review by interested consulting engineers.
S) Preparation of the final report.
The study concluded that from a simple total coast
standpoint, Alternate B - the cat fined system is slightly
favorable over Alternate A - two basins. When other
considerations such as construction staging and park/open
space are taken into account, Alternate A is more
From an engineering standpoint-, either Alternate will
Perform the drainage functions for which they are designed.
The Public works Department made no reeo«w_ndati.on on either
Alternate.
Mr. Glen Baumbach, of Baumbach and Piazza, 323 West Elm
.Jtreet, Lodi, and Por. Kenneth Glantz, 1150 West Bobinnhood
Drive, Stockton, addressed the Council indicating that they
favored the single basin concept.
Following discussion, on motion of Mayor Pro Tempore Murphy,
Olson second, Council selected Alternate B which consists of
one urger basin located at the G -south site.
t
G -AREA STORM DRAIN BASTN STUDY;
City of Lodi Public Works Department
January 1983
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PREFACE
This report is intended to analyze two alternative storm drain systems to
find the most desirable drainage solution for a certain area. A number of
assumptions are made concerning future development without regard to
Measure A (Ordinance 1237), past General Plans or other legal
considerations. These assumptions are based on the report staffs'
engineering judgment and experience gainea from recent development projects
and storm drain design. These assumptions are necessary to provide an
equal basis for comparison, and are not intended to predestine development.
A complete environmental, planning and legal review should be mad- prior to
selection of an alternate.
i
G -AREA STORM DRAIN BASIN STUDY
TABLE OF CONTENTS
INTRODUCTION
1
BACKGROUND
2
BASIC CRITERIA
7
SYSTEM DESIGN
9
SYSTEM COST
14
OTHER CONSIDERATIONS
16
CONCLUSION
18
REPORT STAFF
19
APPENDIX (Calculations)
Under Separate Cover
COMMENTS
20
ii
G -AREA STORM DRAIN BASIN STUDY
Introduction
The purpose of this study is to evaluate two alternate storm drain
basin/pipe systems to serve the G -area. Alternate A consists of two
basins -- G -North and G -South, and Alternate B consists of one larger basin
located at the G -south site. The pipe systems are similar except the main
line between G -North and G -South is substantially larger in Alternate B due
to the elimination of G -North Basin.
The study procedure involved the following:
a Determining basic engineering criteria and making various
assumptions or decisions to insure the comparisons are done on an
equal basis;
o Designing the alternate systems - basin size/depth and pipe sizes;
o Making cost estimates of the system excluding land costs;
o Determining total system cost versus variable land posts;
o Preparation of draft written report;
o In-house technical review;
o Outside review by interested consulting engineers;
o Preparation of final report.
RAMRntiNn
The G -Area is bounded by Lower Sacramento Road on the west, Harney Lane on
the south and the Woodbridge Irrigation District (W.I.D.) Canal on the east
and north. Kettleman Lane (Hwy 12) divides the area into G -North and
G -South. The area is partially developed with "temporary" drainage
facilities. In the north, the Westdale and Sunwest subdivisions utilize
temporary ponds that drain to the already overtaxed Shady Acres pump
station located in the fully developed B-1 area (Exhibit 1). In the south,
Lakeshore Village utilizes a recreational lake to hold storm water which is
eventually discharged to the Beckman (A-2) pump station (Exhibit 2).
The City's Master Storm Drain Plan first identified the two alternates
under study. Exhibits 3 and 4 show the alternates. Since the adoption of
the Master Plan in 1963, a number of changes have taken place:
o the southern boundary of the G -Area has been extended from Century
Boulevard to Harney Lane;
o the E -Area has been designed to drain to the B-2 basin;
o the combined B-2 basin has been built to drain to the Lodi Lake Pump
Station;
o the F -basin is still planned to drain to the G -Area system;
o the Beckman Pump Station which presently drains the A-1, A-2 and
D Areas, will need modification to serve the F and G Areas;
o developments are taking place with high densities and different land
uses than assumed in the Master plan and runoff coefficients were
increased in the 1976 Design Standards. These two factors have
substantially increased basin and pipe sizes shown in the Master
Plan;
o the City acquired 27+ acres for the G -South site in 1974.
In this area, additional temporary drainage systems are unacceptable to the
City Council. The Council has also determined that additional lakes are
unacceptable drainage solutions until their performance in Lodi is proven
satisfactory. Thus, future developments must be served by the Master
Drainage System.
The existing,systems are designed such that they will function with either
G -Area alternate. However, two proposed developments are prompting a
decision on which alternate is to be built. They are Lobaugh Meadows,
located between Kettleman Lane and Century Boulevard west and south of
Lakeshore Village, and Sunwest Unit IV, located between Lower Sacramento
Road and the W.I.D. Canal, south of Vine Street.
Lobaugh Meadows is a planned unit development which, as a Planning
Commission recommended condition of approval, will construct a portion of
the G -South basin. Since expansion of the basin site (most likely to the
east) is required under Alternate B. the design of Lobaugh Meadows must
take this into account. Sunwest Unit IV, although presently outside the
City limits, is in the design stage in preparation for election/annexation
proceedings as required under Measure A. In order to proceed, the
developers must know if they will have to provide for a portion of G -North
or plan on constructing an outfall pipe and a portion of G -South Basin.
- 2 -
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A L TERNA TE B
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BASIC CRITERIA AND ASSUMPTIONS
The Storm Drain Master Plan and the City of Lodi Design Standards adopted
in 1976 provide the basic criteria for storm system design. The main points
are:
1) Design Flow - per Rational Method Q = CiA
where:
Q is the flow in cubic ft. per second,
C is the runoff coefficient (varies with land use,
0.4 for single family residential, 0.8 for
commercial)
i is the 2 year storm rainfall intensity in inches
per hour
A is the area served in acres
2) Design basin volume - adapted from Raticnal Method
V = CIA
where:
V is the volume in cubic feet
C, A per above
I is the total rainfall in a 48 hour, 100 year
storm: 0.4 ft. (4.8 inches)
3) Basin elevat4on - maximum water surface to be at least one foot
below
the top of the lowest catch basin in the drainage
area
4) System hydraulics - designed with Mannings equation, n - 0.013 and
the Rational Method; the hydraulic grade line
(theoretical water surface in pipes, manholes
and catch basins) must be one foot below the top
of any catch basin served when the basin is one
foot below the maximum water surface (See
Exhibit 5)
5) Basin Side Slope - 6 horizontal to 1 vertical
6) Outflow during storm - varies; Beckman Pump Station is designed t's
pump 40 cfs during a storm - 26 cfs from
D -Area, 10 cfs from A-1 Area and 4 cfs from
A-2 Area. The remaining basins (F&G) must
hold all storm flows. After a storm, all
basins will be emptied equally, as fast as
possible. Total time required @ 40 cfs is 6
days for the A-1, A-2, D, G and F Areas
In addition to the basin criteria, a number of assumptions are made based
on the experience City staff has gained from the design, construction and
operation of the existing basins and collection systems. These assumptions
are described below:
- 7 -
CITY OF LODI
. • PUBLIC WORKS DEPARTMENT
SYET cM
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1) Basin configuration - Assumed rectangular with a 20 foot -border
between the top of the slope and the property line and a 300' x 300'
"high ground" area in one corner. Due to aesthetic considerations
or the need for parking, restrooms or other uses, not all of the
basin sites have been available for water storage. This assumption
provides a more realistic estimate of the gross acreage needed to
store the design volume.
2) Basin bottom elevation - Assumed maximum of 1 -foot below the outlet
elevation. In order to provide good slopes for drainage, an
interior drainage system is installed in new basins. As it is
impractical to totally drain this system by gravity, small pump
stations are also installed. Allowing the bottom of the basin to be
below the outlet makes better use of the pump station and results in
less area being needed for the basin.
3) Future development - Assumed to be similar to the average of new
developments in the area. The Storm Drain Master Plan assumed the
entire G -Area would be low density residential. Subsequent changes
in the General Plan have allowed a mix of commercial and high
density residential as well. The runoff coefficients assumed for
the study are the actual factors for developed areas and the average
of Lakeshore Village, Sunwest IV and Lobaugh Meadows for undeveloped
areas except a 200 -foot strip fronting Kettleman Lane is calculated
as commercial.
SYSTEM DESIGN
The alternate systems are shown in Exhibit 6* and summarized in Table 1.
The pipe systems shown are approximate and should not be used for final
design. Without actual street layout and top of curb elevations, the exact
sizes and lengths of the necessary pipes cannot be determined. However,
similar criteria is used in both cases, thus the results are comparable.
Table 1 also includes data for Basins A-1 (Kofu), A-2 (Beckman), D (Salas)
and F (future) for information and comparison.
Examination of Exhibit 6* and Table 1 will reveal the following points:
1) The total basin acreage needed for the G -North and G -South system is
43.0 acres versus 35.5 acres for the combined G system. This is due
to: (a) G -South basin can be up to 8 -feet deep while G -North .is only
6 -feet, and (b) G -South has 4 -feet of freeboard (vertical distance
between existing ground and the water surface) while G -North has
5 -feet - this uses more land area. A graph of volume vs. land area
for various depths is shown in Exhibits 7 and 8. Note that smaller
basins are less efficient with regard to land usage.
2) The collection system for the two alternates is essentially the same
except for the line generally in Lower Sacramento Rc,ad between the
G -South site and the end of the existing 36" pipe in Community Drive
south of Vine Street.
- 9 -
In Alternate B, this line must carry area-wide storm flows to the
G-South site. Thus, the pipe is much larger than in Alternate A
where it only drains the G-North basin or serves adjacent land.
* folded map at end of report
TABLE I
DRAINAGE
AREA
ACRES
BASIN
ELEVATION
DEPTH
Vol.
Area
Approx.
Water
Bottom
Outlet
Basin
Water
Ac -ft
Ac
Ex.
Surf.
Ft.
Ft.
Ground
G -N
302
66
18.0
34
29.0
23.0
24.0'±
11
6
G -S
568
136
27.5*
31
27.0
19.0
20.0'±
12
8
G
880
202
35.5
31
27.0
19.0
20.0'±
12
8
A-1
570
43
120
38
37.0
30.5'
32.3
7.5'
6.5'
(Kofu)
±0.5'
±0.5'
±0.5'
A-2
525
60
16.6
35.5
33.0
24.5'
19.3
11
8.5'
(Beckman)
±1'
±1'
±1'
D
862
94
21.0
42.5
39.2
32.4'
31.6
10.1'
6.8'
(Salas)
-3'
±3'
±3'
F
392
91
20**
30
27.0**
20.0**
23.0±
10'**
7'**
* Existing site; only 25 Acres needed for 8' deep basin
** Tentative
0
CITY CSF LODI
PUBLIC WORKS DEPARTMENT
- 12
CITY OF LODI
PUBLIC WORKS DEPARTMENT
G - A/0 --7- ' ' 8A c`//\/
- )3
SYSTEM COST
The costs for the alternate systems are summarized in Table 2. As with the
design, the costs are approximate and cannot be accurately determined until a
final design is completed. However, they are all based on similar data and are
comparable.
Pipe prices are based on cast -in-place concrete pipe with a 15,. surcharge for
pipes adjacent to Lower Sacramento Road. Jacked pipe prices were used for the
Kettleman Lane crossing.
Basin prices are based on recent prices for Salas Park and include structures,
pumps, telemetry, interior drainage, turf, sprinklers, fencing and major street
improvements. Minor street improvement costs are omitted as it is assumed they
would be comparable in each case and cannot be determined until a street layout
is designed. Excavation is assumed to be at no cost. Engineering or
contingencies are not included, nor are modifications to the Beckman Pump
Station or F -Basin related costs, as they are common to both alternates.
Land costs are difficult to estimate without designating a specific parcel and
having an appraisal done. Therefore, Exhibit 9 shows the total system cost
versus land cost.
TABLE 2
SYSTEM COSTS
Alternate A Alternate B
Collection System $ 636,000 $ 820,000
Basin $ 417,000 G -North $ 814,000
$ 660,000 G -South*
TOTAL $ 1,713,000 $ 1,634,000
Land Needed 16.5 acres net 8 acres
* Based on 25 acre basin; $679,000 if entire 27.5 acres are developed with
shallower basin or more "high ground".
In all cases, Alternate A is more expensive than Alternate B, although the
difference is small. The total costs are within 10% of each other up to a
land cost of $11,000 per acre.
14 -
CITY OF LODI
PUBLIC WORKS DEPARTMENT
U
G)
,V2,000,000
O
v
Z 4/, 500, 000
W
Q ,5/, 000, 000
h
G - A f'FA
TOTAL_ SYSTE11il COST
IS L A IV5 C O� T
---- - ---1 - _ ALT B
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L AND COST -,61A Cl?,E
A LT A - So ooroto G -N �f G -S Basins
TSC=,$/,7/3, 000 f(/8.O Ac--/.5Ac.) Lcnd Cost 91,4,:.
6 -N Exc¢ss 0,6-S
ALT B - Coinbl�? zd G-5 Basin
TSC -01634,000-,0-001,4c.) Lo• -)d Cost $lAc.
Add%CD 6-s
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OTHER CONSIDERATIONS
Because the capital costs of the total systems are so close to each other,
it is reasonable to consider other factors in making a choice between the
alternates. Certainly many factors could be discussed and it is beyond the
scope of this study to adequately review all of them.
Other considerations include:
1) Construction staging - Alternate B, while lower in total system
cost, would be initially more expensive if Sunwest IV were to
develop prior to development of the land north of G -South Basin.
This is due to the larger diameter pipes required in Lower
Sacramento Road, which would nave to be constructed in the first
phase.
2) Operation and Maintenance - Certainly 0&M costs of two basins are
greater than those of one. Two basins provide some additional
drainage flexibility and a higher ssfety factor in the event of a
storm exceeding he design storm. However, two basins present
additional control problems over one basin.
3) Park Space - The Master Drain Plan was conceived not only as a
drainage plan, but a neighborhood park/open space plan as well. The
City's General Plan Open Space - Conservation Element, adopted it]
1973, includes a park standard of 5.0 acres per 1,000 persons and a
serving radius of no more than } mile.
The Element included then existing parks and basins and planned
basins, and indicated a need for an additional 166.93 Acres to meet
the standard for the General Plan Growth Area. The planned C-2
basin/park has since been eliminated from the Storm Drain Master
Plan, reducing planned park land by 20 acres.
Within the G -area itself, the ultimate population could be between
9,300 and 17,200 (based on 5.75 to 10.0 dwelling units per gross
acre and 2.46 persons per dwelling unit). Park area per 1,000
persons would be between 4.6 and 2.5 for Alternate A and 3.8 and 2.1
for Alternate B.
This consideration strongly favors Alternate A - two basin/parks
from both park area and distribution standpoints; although Alter-
nate B and a small neighborhood park in the G -North area could meet
this need.
4) Environmental Impact - An Environmental Impact Report was prepared
on the G -South acquisition in 1974. The EIR assumed that a G -North
basin would be built. No significant impacts were associated with
the proposed purchase. However, it was recommended that a follow-up
EIR be prepared prior to construction.
Eff-M
5) legal/Measure A Considerations - As stated in the preface, these
considerations are beyond the scope of this report. Discussion of
Measure A and its relation to the Storm [rain Plaster Plan will have
to take place before a decision on the Alternates is We.
CONCLUSION
From a simple total cost standpoint, Alternate B - the combined system - is
slightly favorable over Alternate A - two basins. When other
considerations such as construction staging and park/open space are taken
into account, Alternate A is more advantageous.
From an engineering standpoint, either Alternate will perform the drainage
function for which they are designed. The Public Works Department makes no
recommendation on either Alternate.
0
REPORT STAFF
Jack L. Ronsko, Public Works Director - general direction and review
Glenn E. Robison - Assistant City Engineer - general review
Glen Baltzer, Street Supervisor - operational review
Richard C. Prima, Jr., Associate Civil Engineer - design, report
Wes Fujitani, Junior Civil Engineer - design review
James Monroe, UOP Co-op Intern - design check
Wesley Ouye, Civil Engineering Technician - graphics
Diane Wood, Word Processing
19 -
COMMENTS
Copies of this study have been sent to the following parties and their
comments are noted: (as of 1-31-83)
Community Development Dept. - no comment
Parks & Recreation Dept. - requested a presentation
be made to Parks & Recreation Commission
(to be made 2-1-83)
Glen Baumbach (engineer for Sunwest IV) - see attached letter.
Ken Glantz (engineer for lobaugh MeaOows) - called in question
regarding pipe alignment and will send letter. Alternate
pipe alignment is being studied.
- 20 -
C2 C3
0 0 a (� D n U- � 323 West Elm Street
CEJ Lodi, California 95240
BAUMBACH & PIAZZA
January 20, 1983
Mr. Richard Prima
Department of Public Works
City of Lodi
Lodi, California
RE: G -Area Basin Study
Dear Rich:
Phone (209) 368-6618
The report as prepared shows a master plan for the entire Gn and
Gs basin area. The report appears to be complete and will be help-
ful in the future. It is always easy to review someones report and
criticize, and that is not the intent of this letter. The report
does indicate to me that there are some other options to consider
and we offer the following comments:
One Basin or Two Basins
I believe it would be in the best interest of the City to have one
basin for operation and maintenance. Initial costs of two basins
with pumps, electrical controls and telemetering, landscaping, etc.,
would be more costly,
Gs Basin is necessary under any option, and if you decide to use
two basins and build Gn Basin, the Gn Basin will not function with-
out Gs Basin.
The area immediately north of Kettleman Lane (between Kettleman
Lane and the south line of proposed Sunwest IV) may be better served
by a line running south through the Lobaugh property to the Gn Basin.
The line should have been run in Mills Avenue location and would
have better divided the area. The plan as shown proposes all the
drainage run westerly to Lower Sacramento Road and then southerly.
We also believe there should be a line in Lower Sacramento Road to
serve the area in the future "F" Basin area and possibly future
development along Lower Sacramento Road. This would also provide a
certain amount of flexibility and perhaps allow development that
would not be totally dependent on other developers.
R.F-CEIVED
JW4 2 U 1963
CITY OF LODI
In regards to the proposed Sunwest No. 4 development, we would
recommend eliminating the Gn Basin and provide a pipeline down
Lower Sacramento Road and build the northerly portion of Gs Basin.
We also recommend that the master plan provide for a line from the
area north of Kettleman Lane through the Lobaugh property to the
Gs Basin. This area is too big to not have a master line not run
through it. This would provide the greatest amount of flexibility
to the entire area.
The necessity of a park in the vicinity of Sunwest No. 4 should not
be a condition for basin determinations. Park requirements should
stand on their own merits. We also realize that a park is an add-
itional benefit due to basins.
We appreciate the opportunity to comment on this report and feel
that a lot of valuable information is now available due to this
study to provide for good planning for this area.
Sincerely,
J4 -)d a4-"�46.�
GLEN I. BAUMBACH
GIB:jm
cc: Fred Baker