Agenda 01/15/2008 Item #10B
Agenda Item No. 10B
January 15, 2008
Page 1 of 7
EXECUTIVE SUMMARY
Recommendation to approve completion of the Willow West Stormwater Improvements on
Mentor Drive, Project No. 510076.
OBJECTIVE: To provide the Board of County Commissioners with a complete summary of
the stormwater issues in the Willow West neighborhood and to fully explain staffs
recommended plan of action.
CONSIDERATIONS: The Willow West neighborhood has experienced poor stormwater
drainage conditions for many years. Numerous complaints of standing water and street flooding
have been received since the early 1990's. For over ten years County staff spent a significant
amount of time and effort trying to improve the situation. Storm sewer pipes were repeatedly
cleaned out. Roadside swales in the area were re-dug. Modifications to sections of the rear yard
swale system were made. Driveway culverts were installed at alternate elevations. All efforts to
try to alleviate the poor drainage situation resulted in little or no improvement.
In 2003 the Storm water Department began to develop a remedial engineering plan to address the
issue. The decision to move forward with a county plan of corrective work was based on
detection and analysis of several contributing factors. These factors have had a cumulative effect
on the system resulting in nuisance flooding dming the rainy season which affects the health,
safety, and welfare of the Willow West residents.
One factor is the design of the original system. It is unique in that it retained one (I) full foot
(depth) of water in an interconnected system of front and rear yard swales. Rear yard swale
retention/detention systems were somewhat common in the 1980s and 90s. Considered an
economical way to develop small subdivisions by placing a small portion of the required water
management area behind each home, rear yard retention swales quickly became very
objectionable to homeowners, the cnd users, when water lay stagnant around their homes for
extended periods. Cunent code prohibits the use of rear yard swales for stonnwater detention
and requires that all retention/detention areas be located in common areas.
More than half of the residential driveways in Willow West were constructed as swale
driveways. Swale driveways are driveways with no culvert and are constructed to match the
geometry and elevation of the adjacent roadside swale. Storm water is intended to flow across a
swale driveway unimpeded maintaining a very shallow depth. This is generally the case and not
a problem, again done to reduce development costs by eliminating the expense of a driveway
pipe. In the case of Willow West however with each swale driveway being connected to and
part of the retention system, standing water one foot deep by several feet wide covered many
driveways during most of the rainy season.
Another contributing factor is that system modifications were made, most with good intentions,
some with county assistance and permits, and some by residents with no permits, all intending to
eliminate the standing water condition. Unfortunately, all the modifications only made matters
worse. Sections of rear and front yard swales were filled in. Some portions of rear yard swales
Agenda Item NO.1 08
January 15, 2008
Page 2 of?
were enclosed with pipe or conduit called infiltrators. The majority of the enclosures resulted in a
loss of retention area and conveyance capacity further exacerbating the problem.
In the case where driveways were constructed with culvert pipes, not swale driveways, the
bottom of the pipes were set at too high an elevation. This has created multiple blockages in the
system. Stormwater flow cannot reach the drainage outlet. These en-ors were caused by the
County's misunderstanding of the original plan complicated by misinterpretation of some of the
subsequent permitted modifications to the original system. Other contributing factors identified
are: (1) the fact that installation of the new weirs in the Cocohatchee Canal have raised the
elevation of the water table in the Willoughby Acres area by several feet. This is a good water
resource management measure with extreme positive benefits to the area, which can however
decrease the rate of drainage of an adjacent retention swale system, and (2) installation of a
sidewalk on the south side of Mentor Drive associated with construction of the neighborhood
park. This decreased the size of the original swale design affecting a change in conveyance of
stormwater to the drainage outlet.
On March 27, 2007, StOllliwater Department staff brought a recommendation to the Board
rcquesting endorsement of the Willow West Stormwater Improvement Project approach (Item
lOB). Sufficient surveying and engineering work had been completed and a project was
designed to rcmediate the issucs. The project approach is to basically reconstruct the watcr
management system within the road right-of-way adjacent to the front yards of all the Willow
West residential lots. This reconstruction would allow for establishment of a stormwater runoff
collection system of swales with a consistent sloping, interconnected drainage flow-line
providing positive conveyance to a receiving ditch. Under the new design, the one foot of
standing water would be reduced. The plan includes replacing the majority of the residential
driveways with installation of new driveway culverts.
On March 27, 2007, staff may not have adequately explained to the Board all the contributing
factors leading to the problems within Willow West. The Board directed staff to complete only
the reconstruction activities on the swale within the county right-of:way along Johnny Cake and
Mentor Drives. The Board determined that the residents are responsible for any reconstruction
of driveways and driveway culvcrts.
Based on this direction, to date staff has facilitated completion of most of the swale
reconstruction on both Johnny Cake and Mentor Drives. Nine (9) swale driveways on Johnny
Cake Drive were reconstructed with culverts per the remedial plan and paid in full by each
resident. None of the twenty-Jour (24) affected residents on Mentor Drive have reconstructed
their driveways and culverts. UnfOliunately, even though a substantial amount of work has been
completed, the project currently remains unfinished and nonfunctional.
On November 13, 2007, the Board heard a petition and presentation by Susan Thompson (Item
6C), a resident of Willow West, requesting that the Board consider revisiting the issues and
staffs proposed solution to the problems of Willow West. Ms. Thompson's presentation
included two requests: (1) that the newly reconstructed roadside swales be reduced in size and,
(2) that the Board approved the expenditure of county funds to complete the remainder of the
Agenda Item NO.1 08
January 15, 2008
Page 3 of 7
improvements, including the replacement of the driveway culverts. The Board directed staff to
bring forward a full airing of the issues and staffs proposed solution.
The Stormwater Department cannot agree to the first request, the reduction in the roadway
swales. The portion of the stormwater improvements recently completed and the remainder yet
to be completed have been designed to collect and convcy runoff away from the homes of
Willow West as well as from the roadway surfaces of Johnny Cake and Mentor Drives. The
improvement plan was designed to make the best use of the roadside area located within county
right-of-way, providing the greatest level of flood protection, water quality treatment and runoff
conveyance. The new roadside swales range in size from a 4 to 6 foot bottom width. This size
swale may appear to be excessive but is in fact the size necessary in order to meet water
management criteria of attenuation, treatment and conveyance and is fully within the existing
County rights of way. The plan also utilizes much of the originally constructed system by
simply re-establishing connections to existing components (pipes) and by making minor
modifications to others (catch basins). The so lution is realized by creating adequate area and
volume to capture storm water runoff and by restoring connectivity allowing for' adequate
conveyance to the outlet without retaining one foot of water. The improvement project does not
consider any of the remaining portions of the existing rear yard retention area, as the majority of
it has been encroached upon and it is unfeasible to restore connectivity to and within it.
The Stormwater Department does, however, support the second request to complete the
remainder of the improvements, including the driveway culvert replacements, with project funds
on Mentor Drive, but not on Johnnycake Drive. This position acknowledges that residents on
Mentor Drive are receiving stonnwater runoff from Johnnycake Drive, in addition to runoff from
the roadway and from their properties. As such, the specific value to Johnnycake Drive residents
warrants their replacement of their driveway culvelis, which, where needed, have already been
completed and paid for by the residents on Johnnycake. Improvements already completed on
Johnnycake are not currently realizing the benefits because the culvert work has not yet been
done on Mentor, further supporting County funding of the Mentor Drive culvert replacements.
Staff has prepared a detailed Power Point presentation to highlight all the contributing factors
leading to the problems within Willow West, to show why the new swale cross section is
necessary. Staffrecommends that the project be completed as designed on Mentor Drive with no
reduction in the recently reconstructed road side swale system. Current cost estimates to
complete the work range between $310,000 and $360,000.
FISCAL IMPACT: Funds in the amount of $331,234 are available in the Stormwater Capital
Fund (Fund 325), Project No. 510076. Source of funds are Ad Valorem taxes. If the project
completion is approved, the bidding process can begin and absolute project costs will be
determined.
GROWTH MANAGEMENT IMPACT: There is no impact to growth management.
.~
RECOMMENDATION: That the Board of County Commissioners approve completion of the
Willow West Stormwater Improvcments on Mentor Drive including the driveway culvert
replacements, Project No. 510076.
Aaenda Item I~o. 10B
~ January 15, 2008
Page 4 of 7
Prepared By: Jerry Kurtz, P.E. Principal Project Manager, Stormwater Department
Attachment: Location Map
Page lof2
Agenda Item NO.1 OB
January 15, 2008
Page 5 of 7
COLLIER COUNTY
BOARD OF COUNTY COMMISSIONERS
Item Number:
10B
Meeting Date:
This item to be heard at 2:30 p,m. To provide the Board of County Commissioners with a
complete summary of the stormwater issues in the Willow West neighborhood and to fully
explain staffs recommended plan of action. (Gerry Kurtz, Transportation/Stormwater
Management)
1/15/2008 900:00 AM
Item Summary:
Prepared By
Gerald Kurtz
Senior Engineer
Date
Transportation Services
Storm water Management
12/26/20071;11:04 PM
Approved By
Gerald Kurtz
Senior Engineer
Date
Transportation Services
Stormwater Management
12/26/2007 1 :29 PM
Approved By
Caroline Soto
Administrative Assistant
Date
Transportation Services
Transportation Engineering and
Construction
12/27/20073:18 PM
Approved By
Norm E. Feder, A1CP
Transportation Division Administrator
Date
Transportation Services
Transportation Services Admin.
1 2/27/2007 7: 54 PM
Approved By
Sharon Newman
Accounting Supervisor
Date
Transportation Services
Transportation Services Admin
1/2/20088:44 PM
Approved By
Pat Lehnhard
Executive Secretary
Date
Transportation Services
Transportation Services Admin
1/3/200811:18 AM
Approved By
OMS Coordinator
Applications Analyst
Date
Administrative Services
Information Technology
1/3/200812:47 PM
Approved By
Susan Usher
Senior Management/Budget Analyst
Dare
County Manager's Office
Office of Management & Budget
1/4/20085:19 PM
Approved By
Michael Smykowski
Management & Budget Director
Date
County Manager's Office
Office of Management & Budget
1/7/200812:46 PM
file://C:\AgendaT est\Export\98-J anuary%20 15, %202008\ 10. %20COUNTY%20MANAG ER... 1/9/2008
Page 2 of 2
Aaenda item ~'.jo. 108
~ January 15, 2008
Page 6 oi 7
Approved By
James V. Mudd
County Manager
Date
Board of County
Commissioners
County Manager's Office
1/7/20085;43 PM
file://C :\Agenda T est\Export\98-J anuary%20 1 5,%202008\ I O. %20COUNTY%20MANAGER... 1/9/2008
COLLIER COUNTY
BOARD OF COUNTY COMMISSIONERS
PROJECT No. 510072
WILLOW WEST WILLOUGHBY ACRES DRAINAGE
PROJECT LOCATION MAP
Agenda Item NO.1 OB
January 15, 2008
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PROPOSED BY, COLLlER COUNTY BOARD OF COUNTY COMMISSION ERS
TRANSPORTATION SERVICES DIVISION
STORMWATER MANAGEMENT DEPARTMENT
HORSESHOE SQUARE. SlJITE No 214,2685 soon! HORSESHOE DRIVE
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I PROJECT MANA~~R GERALD N. KURTZ DATE AUGUST.2004
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