Meadows Addn 2-CS 920413ALBERT H. HALFF ASSOCIATES, INC.
ENGINEERS · SCIENTISTS · SURVEYORS
DALLAS · ARLINGTON · CHICAGO · FORT WORTH
8616 NORTHWEST PLAZA DRIVE ,, DALLAS TEXAS 75225
214 739 0094 · FAX 2 ! 4 739-0095
April 13, 1992
AVO 12036
City of Coppeli
255 Parkway Boulevard
Coppell, TX 75019
Attn: Ken Griffin, P.E., City Engineer
Re: Meadows Subdivision (Sm ainage Improvements
Dear Ken:
Enclosed please find two sets of bluelines of the above referenced construction plans. A
brief report detailing the findings of our in depth analysis of this drainage system is also attached
for your information. This analysis shows that the proposed recommended drainage
improvements will significantly improve the drainage within this subdivision. We also
recommend that city staff made the initial contact for acquisition of the required drainage
easement at the comer of Meadowglen Circle and Woodmoor. Please let me know how you wish
to handle this. The property owners name, address and phone is provided in the report. This
information should be verified through the City of Coppell's tax records.
I apologize for the delay in submitting these plans. As we discussed on the phone we had
numerous problems with matching plans for the various stages of construction. Many of the inlet
and pipe sizes had to be verified in the field, where possible. Discrepancies between duplicate
sets of plans on ~e at the Public Works Department has also necessitated a change in the design
f~ the Stage I Improvements. The two sets of plans show differing pipe sizes for Lines A and
B in Meadows - Section 1. We confn'med the pipe size on Line A and utilized that set of plans
showing the larger pipe sizes as the most current. This means that Stage I plans need to be
extensively modified. However, the good news is that the construction cost should be lower.
We will resubmit these plans by Friday. A status report and new schedule is attached for your
use.
Please feel free to call if you have any questions or comments.
Yours very truly,
ALBERT H. HALFF ASSOCIATES, INC.
n Hansen, P.E.
Enclosure
TRANSPORTATION
WATER RESOURCES LAND DEVELOPMENT
SURVEYING GLOBAL POSITIONING SYSTEM (G P S}
LANDSCAPE ARCHITECTURE
MUNICIPAL ENVIRONMENTAL
REMOTE SENSING AND MAPPING
PLANNING
STRUCTURAL
STATUS REPORT
PHASE 1 DRAINAGE IMPROVEMENT PROJECTS
CITY OF COPPELL, TEXAS
ALBERT H. HALFF ASSOCIATES, INC.
APRm, 1992
Brooks Lane - Stage 1 Partial:
Anticipated
Submission Date
Comp~te
Sandy Knoll Area:
Construction Plans - Submitted for City Review
Specifications - Submitted for City Review
Meadows Stage 1:
Construction Plans - Initial Submittal
Resubmit
Specifications
3-23-92
4-17-92
4-27-92
Meadows Stage H Diversion:
Constzucfion Plans - Initial Submittal for City Review
Specifications
Easements - 15% complete; one easement required
4-13-92
4-27-92
05-92'
Brooks Lane Stage 1 Diversion - Easements and Preliminary Design
Initial Preliminary Design, Property Ownership and
Layout of Easements
Easement Negotiations and Final Submittals
* Estimated schedule dependent upon easement negotiations
04-21-92
05-92°
CITY OF COPPELL
PHASE 1 DRAINAGE IMPROVEMENTS
MEADOWS SUBDIVISION
AVO 12036
APRIL 1992
L Background
The Meadows Subdivision was conslxucted in six phases from 1979 to 1989. The
storm sewer systems throughout this neighborhood converge near the intersection of Parkway
Boulevard and Meadowglen Circle ouffalling tO the east into the Lakes of Coppell. During the
course of the City-Wide Storm Water Management Stztdy (1990-91), complaints of slxeet flooding
were reported on Meadowglen Circle, Meadowrun Drive and Leslie Lane. The preliminary
analysis included in that report showed problems in several areas, as well as, a significant lack
of capacity in existing ouffall system.
II. Analysis of Existing Conditions
A detailed analysis was performed in conjunction with the preparation of
construction plans for the Stage H diversion th. rough Waterside Estates. The existing system has
less than 5-year capacity with approximate street flooding depths as shown in Table 1, auached.
In general, the original drainage system was designed for a 5 year capacity with
overflow through the streets to Parkway Boulevard. This system was designed in seven stages
by four different engineering f'ms. Hydraulic grade calculations were not carried fl~rough from
one set of plans to the next and the overall system does not appear to have ever been completely
analyzed. For example, Meadows Section 6, west of Meadowrun and south of Parkway, was
designed for 100 year capacity. However, there is less than 5-year capacity at the main trunk
line on Parkway Boulevard, therefore, the majority of this flow is bypassed in the streets due to
pipe capacity. All of these bypass flows ultimately flow east on Parkway Boulevard into the
currently developing Waterside Estates No. 1 and the Lakes of Coppell. Drainage complaints
have not been logged in this subdivision to date, but flooding problems may increase as the area
develops and houses am built in this subdivision.
III. Proposed Drainage Improvements
The proposed storm water diversion and additional inlets will bring the entire
system up to approximately 25 year capacity except in the area of Meadowglen Circle and
Page 1
Meadowrun Drive, north of Parkway Boulevard. The existing 30 inch RCP at Parkway and
Meadowrun has a pipe capacity of only approximately 32 cfs. Inlet capacity in this area is 68
~fs. Flows which can not get into the pipes will bypass to the east down Meadowglen Circle to
Parkway Boulevard. Estimated depths of street flows with the diversion in place are shown on
Table 2, attached.
IV. Recommendations
As can be seen from comparison of Tables 1 and 2, depths of water in the streets
has been reduced significantly with the proposed improvements. In fact, the improved condition
100 year stxeet flows con'elate to approximately the 5 year flows under current existing
conditions. This is true in the majority of the subdivision with the exception of Meadowglen
Circle north of Parkway Boulevard. There is insufficient pipe capacity in System H - Line B (see
Drainage Area Map - Sheet DA1) to add additional inlets in this area. Options for improvements
would be 1) an additional storm sewer diversion to the north through Waterside Estates No. 2
or 2) replacement and extension of the north lateral at Parkway Boulevard and Meadowglen
Circle. However estimated flow depths on Meadowglen Circle are only 7 inches over the top
of curb for the 100 year flood and there have not been any homeowner complaints to date. I-lalff
Associates does not recommend any additional drainage improvements at this time. The city
should monitor the area (Meadowglen Circle) closely, evaluate future complaints, if received,
before proceeding with drainage improvements in this area.
V. Easements
An easement for the diversion through Waterside Estates No. 1 was obtained by
city staff in November 1991 through the platting process for this subdivision. An additional 10
foot drainage easement is required in the Meadows Subdivision Section 2 on Lot 1, Block F for
connection to the existing storm sewer system. Dallas County records show the following
ownership information for this lot:
William Harrison, et al.
154 Meadowglen Circle
Coppell, Texas 75019
(214) 462-9049
We recommend that the initial contact letter requesting this easement come from city staff. Halff
Associates will then follow through with additional contact and/or negotiations.
Page 2
TABLE 1
ESTIMATED FLOODING DEPTHS - EXISTINC. CoNDrr,oNs
5-Year I 25-Year I 100-Year
Location Flood Depths Over Top of Curb
Leslie at Sag Inlets 3" 4" 6"
Meadowglen Ch'cie and Woodmoor 3" 5" 7"
Meadowrun South of Parkway 4" 7" 10"
Parkway Boulevard East of 3" 7" 9"
Meadownm Drive
Meadowglen Circle (East) at 5" 6" 7"
Meadowglen Circle (South)
Intersection of Parkway Boulevard 6" 11" 16"
and Meadowglen Circle East to
Lakes of Coppell
TABLE 2
ESTIMATED FLOODING DF_,FrltS. PROPOSED CoNDmoNs
25-Year 100-Year
Depth Depth
Location Q~ in Street Q~o in Street
Over Top of Curb
Leslie at Sag Inlets 6 cfs 21 cfs _+2" +3"
Meadowglen Circle at 12 cfs 33 cfs _+3" _-~-4"
Woodmoor
Meadowrun South of Parkway 2 cfs 3 cfs +1" +1.5"
Parkway Boulevard East of 11 cfs 27 cfs +2" +3"
Meadowrun
Meadowglen Circle (East) at 55 cfs 69 cfs _+6" +7"
Meadowglen Circle (South)
Parkway Boulevard at 32 cfs 72 cfs +3" _+5"
Meadowglen Circle East to
Lakes of Coppell