40-Attachment F - Drain Report A. CIP 46142452 Lenwood Ln.pdf
PDF 22 MB Posted
- Solicitation number
- IFB-26-00085
- Issued by
- Hillsborough County, Florida
About this file
This is a drainage report submitted by Urban Center on behalf of Hillsborough County Public Works for the Lenwood Lane Culvert Replacement project (CIP No. 46142.452), located in the unincorporated community of Gibsonton, Florida. The project proposes to replace three existing 60-inch corrugated metal pipes (CMPs) with three 60-inch reinforced concrete pipes (RCPs) at a culvert crossing under Lenwood Lane between Dagwood Way and Entrance Way. The existing culvert presents safety concerns due to erosion at the channel bottom and culvert walls, and the west end lacks proper end treatment, causing deterioration. The project is scheduled for construction under Hillsborough County's WORCs contract. The drainage analysis evaluated the culvert replacement design against requirements established by the Southwest Florida Water Management District (SWFWMD) Statewide Environmental Resource Permit and Hillsborough County standards, utilizing the Alafia River Watershed SWMM5 model.
The proposed improvements will include installation of endwalls at both the upstream and downstream ends for soil stabilization and erosion control. Modeling analysis comparing existing and proposed conditions across multiple storm events (2.33-year, 5-year, 10-year, 25-year, 50-year, and 100-year frequencies) demonstrates that peak stage elevations on the upstream side of the proposed 60-inch RCP will decrease across all storm events, with reductions ranging from 0.05 to 0.13 feet. The project includes maintenance protocols requiring periodic mowing and cleaning of ditches and swales, monthly inspection of inlet grates, and yearly inspection of pipes and inlets. The professional engineer seal was issued by Haylee LaTorre, P.E. (License No. 61732) on July 10, 2023. This project is one of three culvert replacement initiatives in the broader Hillsborough County solicitation estimated at $1,958,866.12 with a 6 percent Small Business Enterprise subcontractor participation goal.
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Text version
LENWOOD LANE
CULVERT REPLACEMENT
Hillsborough County Public Works County Center, 22nd Floor
601 E. Kennedy Blvd.
Tampa, FL 33602
C.I.P. Project No. 46142.452
Submitted by:
2 Urban center
4890 W. Kennedy Blvd . FL 33609 Phone: 813.641.1200
July 10, 2023
Haylee LaTorre, State of Florida, Professional Engineer, License No. 61732.
This item has been digitally signed and sealed by Haylee LaTorre, P.E. on 7/10/2023.
Printed copies of this document are not considered signed and sealed and the signature must be verified on any electronic copies.
Haylee LaTorre, P.E.
#61732
I. PURPOSE
The intent of this drainage report is to evaluate the culvert replacement design for the
Lenwood Ln culvert replacement project (Hillsborough County CIP No. 46142.452). The purpose of this project is to replace the existing (3) 60” CMP with (3) 60” RCP. The proposed improvements are scheduled to be constructed under Hillsborough County’s
WORCs contract.
This drainage report provides an assessment of the proposed drainage improvements that satisfy the requirements established by the Southwest Florida Water Management
District (SWFWMD) Statewide ERP and Hillsborough County.
II. DESCRIPTION
This project is located at a culvert crossing under Lenwood Ln. between Dagwood Way and Entrance Way within the unincorporated community of Gibsonton in Section 03, Township 31S, and Range 20E.
This project lies within the Alafia Watershed of
Hillsborough County. The
Alafia Watershed covers approximately 418.5 square miles.
The location of the
Lenwood Ln Culvert
Replacement project is illustrated in Figure 2 below.
ALAFIA WATERSHED
Figure 1. Watershed Location
Figure 2. General Vicinity Map
III. EXISTING CONDITIONS
Lenwood Ln is a local roadway. The area surrounding the project were developed with a mixed of residential properties and open space. The location of the existing triple 60” CMP culvert ends poses safety concerns due to erosion at the channel bottom and culvert wall. Additionally, the west end of the culvert lacks an end treatment which causes the deterioration of the existing CMP as evident in Photo 3.2. This project will enhance the service life and function of the culvert as well as improve roadway safety.
PROJECT
LOCATION
This project lies within the Alafia watershed SWMM Subbasins SUB730690 and
SUB739522. These subbasins encompases 62.7 acres and 62.7 acres respectively.
The Alafia River SWMM’s existing conditions model (ECM) data was utilized for this project. The following nodes will be evaluated in the Revised in Existing Conditions
Model (RECM) to assess the project’s potential impact to the peak stages:
1. Node 739526 represents the South West side (upstream) of the Lenwood Ln culverts. The invert elevation was modified to match lowest invert of the existing triple 60” CMP (Elevation 68.76 ft.)
2. Node 739705 represents the North East side (downstream) of the Lenwood Ln culverts. The initial elevation was modified to match lowest invert of the existing triple 60” CMP (Elevation 68.6 ft.)
3. Node 730690 is located at the downstream section of the channel downstream of
Lenwood Ln. No modication was to this nodes is proposed.
4. Node 730665 is located further downstream of the channel. No modication was to this nodes is proposed.
The project’s existing culverts (Pipe Link 1730710, 2730710, 739526a) were modified to reflect the surveyed conditions. Please note that the Alafia River Watershed SWMM5
Photo 3.1 Endwall & Pipe at SW side of Lenwood Ln
Photo 3.2. Endwall at NE side of Lenwood Ln model link connectivity data indicates that the upstream to downstream direction in the ditches connected by the Lenwood Ln culvert flows from southwest to northeast. See
Figure 3 below for reference to the ditch flow direction.
See Figure 3.4 for the SWMM5 Alafia Watershed Connectivity (ECM) illustrates the
ICPR ECM Nodal Connectivity Map
Figure 3.3.
Watershed Location
IV. PROPOSED CONDITIONS
The Lenwood Ln Culvert Replacement project proposes to replace the existing triple 60”
CMPs with triple 60” RCPs. Endwalls will be installed at the upstream and downstream ends for soil stabilization.
The following are modifications to the PCM ICPR data to reflect the proposed improvements:
1. Prop Pipe Link P-739526a, P-1730710, P-2730710 was modified to 60” RCP and the inverts were adjusted to reflect the proposed invert of the triple culvert.
See Figure 3.5 for ICPR Proposed Conditions Model (PCM) nodal connectiviity.
The tables below illustrate the peak stage elevation differences between the existing and post improvement conditions in the 2.33-year, 5-year, 10-year, 25-year, and 100-year and 24 hours storm events.
Based on the results, the peak stages on the upstream side (Node 739526) of the proposed 60” RCP decreased in all storm events in the PCM. There are also small decreases in the downstream side (Node 730705) in some storm events. There are no differences in the peak stage for nodes 730690 and 730665 in all storm events.
RECM PCM RECM PCM
2.33 72.34 72.29 -0.05 2.33 72.2 72.2 0.00
5 73 72.92 -0.08 5 72.79 72.79 0.00
10 73.62 73.52 -0.10 10 73.33 73.31 -0.02
25 73.81 73.7 -0.11 25 73.48 73.46 -0.02
50 74.09 73.96 -0.13 50 73.67 73.66 -0.01
100 74.15 74.02 -0.13 100 73.72 73.7 -0.02
RECM PCM RECM PCM
2.33 69.79 69.79 0.00 2.33 69.54 69.54 0.00
5 70.55 70.55 0.00 5 70.26 70.26 0.00
10 71.35 71.35 0.00 10 71.02 71.02 0.00
25 71.78 71.78 0.00 25 71.45 71.45 0.00
50 72.47 72.47 0.00 50 72.09 72.09 0.00
100 72.77 72.77 0.00 100 72.37 72.37 0.00
Difference in
Peak Elev (ft)
24-hr Design
Storm
Frequency
(Year)
TABLE A - EXISTING CONDITIONS MODEL (ECM) AND
PROPOSED CONDITIONS MODEL (PCM) PEAK STAGES
24-hr Design
Storm
Frequency
(Year)
Node 739526
SW (U/S) Side of Headwall Difference in
Peak Elev (ft)
24-hr Design
Storm
Frequency
(Year)
Node 730705
NE (D/S) Side of Endwall Difference in
Peak Elev (ft)Peak Stages (ft) Peak Stages (ft)
Node 730665 Difference in
Peak Elev (ft)Peak Stages (ft) Peak Stages (ft)
24-hr Design
Storm
Frequency
(Year)
Node 730690
OPERATION AND MAINTENANCE INSTRUCTION
A. OPERATION
The project’s drainage system is a gravity system and requires no operational protocols.
B. MAINTENANCE
i. Ditches and Swales: All ditches and swales shall be periodically mowed and cleaned. During the mowing operation, ditches and swales shall be inspected for bare spots, damage, and erosion. Any bare spots greater than one square foot in area shall be seeded or sodded the replace grass cover. In cases of erosion or damage where underlying soil is missing, the missing soil shall be replaced, and area brought back to grade then seeded or sodded as required.
ii. Inlet Grates (if applicable): Inlet grates will be checked monthly for damage or blockage. Any damage grates will be replaced or repaired. Any debris blocking full flow through the gate will removed.
iii. Pipes and Inlets: Pipes and inlets will be inspected yearly for damage or blockage. Any damage pipes or inlets will be repaired or replaced. Any damaged pipes or inlets will be repaired or replaced. Any trash debris will be removed.
ALAFIA RIVER WATERSHED SWMM5
RECM AND PCM
(MODEL FILES SUBMITTED UNDER
SEPARATE FILE)
File details come from the government source that posted it. Updated .