41-Attachment F - Drain Report B. CIP 46142490 303 4th Ave SE.pdf
PDF 14 MB Posted
- Solicitation number
- IFB-26-00085
- Issued by
- Hillsborough County, Florida
About this file
This is a drainage report prepared by a professional engineer for Hillsborough County Public Works regarding the culvert replacement project at 303 4th Avenue SE (CIP Project No. 46142.490) in the Ruskin area. The report evaluates the replacement of an existing 43"x68" corrugated metal pipe (CMP) culvert with a 43"x68" elliptical reinforced concrete pipe (ERCP) culvert and associated headwalls. The project is located in the Little Manatee Watershed and is part of Hillsborough County's broader culvert replacement initiative, which includes two additional culvert sites at Lenwood Lane and 1st Avenue NW, with a combined project estimate of $1,958,866.12. The existing culvert is in poor condition with collapsing endwalls causing erosion of adjacent roadway pavement. The proposed improvements include extending the culvert to meet minimum clear zone requirements for improved public safety and upgrading a nearby 12" RCP driveway culvert to 14"x23" ERCP.
The drainage analysis demonstrates that the proposed culvert replacement will not cause significant adverse impacts to upstream and downstream nodes, with the modeling results showing minor improvements at the upstream section. Peak stage elevation data across multiple storm frequencies (2.33-year through 100-year, 24-hour events) indicates negligible differences between pre- and post-improvement conditions at critical nodes. The Hillsborough County Engineering and Operations Department is seeking competitive sealed bids from qualified contractors, with a 6% Small Business Enterprise (SBE) subcontractor participation goal established. Questions and requests for interpretation must be submitted no later than 14 calendar days after solicitation issuance, site visit, or pre-bid conference, whichever occurs later. The project requires implementation of routine maintenance protocols including periodic ditch and swale mowing, monthly inlet grate inspections, and yearly pipe and inlet inspections to maintain the gravity drainage system.
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Text version
303 4th AVE SE
CULVERT REPLACEMENT
Hillsborough County Public Works County Center, 22nd Floor
601 E. Kennedy Blvd.
Tampa, FL 33602
C.I.P. Project No. 46142.490
Submitted by:
2 Urban Center
4890 W. Kennedy Blvd . Su i te 985 Tampa, FL 33609
Phone: 813.641.1200 Fax: 813.633.2110
CA# 25990
November 7, 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 11/7/2023.
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
303 4th Ave SE culvert replacement project (Hillsborough County CIP No. 46142.490).
The purpose of this project is to replace the existing 43”x68” CMP and headwalls with
43”x68” ERCP and headwalls. The proposed culvert will be extended to meet minimum clear zone requirements and improve public safety. The proposed improvements are scheduled to be constructed under Hillsborough County’s WORCs contract.
This drainage report provides an assessment of the proposed culvert replacement that satisfies the requirements established by the Southwest Florida Water Management
District (SWFWMD) Statewide ERP and Hillsborough County.
II. DESCRIPTION
This project is located west of 303 4th Ave SE in the Ruskin area, within Section 08, Township 32S, and Range 19E.
This project lies within the Little Manatee Watershed of Hillsborough County. The Little
Manatee Watershed covers approximately 228.35 square miles.
LITTLE MANATEE
WATERSHED
Figure 1. Watershed Location
The location of the 303 4th Ave SE Culvert Replacement Project is illustrated in Figure 2 below.
Figure 2. General Vicinity Map
III. EXISTING CONDITIONS
4th Ave SE is a local roadway that serves single family residential homes. This area is fully developed and is comprised mainly of single-family residential properties.
The existing neighborhood’s drainage discharges northward via ditch which oufalls to
Little Manatee River. The existing 43”x68” CMP is currently in poor condition. The endwalls and pipe ends are collapsing which also causes the
4th Ave edge of pavement asphalt to erode.
This project lies within the Little Manatee watershed SWMM Subbasins SUB922102 and
SUB922104. This subbasins encompases 1.54 acres and 5.61 acres, respectively.
PROJECT
LOCATION
Photo 3.1. Eroding Endwall and Culvert
(South Side)
The Little Manatee SWMM’s existing conditions model (ECM) data was utilized for
RECM model and the project’s existing culvert (Pipe Link P922104a) was modified to reflect the surveyed conditions. Subbasin SUB922104 was further subdivided to model the driveway culvert directly east of the project. The following was included in the
RECM:
• SUB92210401 (0.48 acres) was subvided from SUB2210401. This subbasin represent the drainage area upstream of the driveway culvert.
• P9221041 (12” RCP) represents the driveway culvert
• W9221041 represents the driveway overtopping flow
All other nodes and links adjacent to the project’s boundary remain unchanged. Table
A below illustrates the peak stage comparison result between the Little Manatee River
Water ECM and RECM.
ECM Peak
Stage (ft)
RECM Peak
Stage (ft)
ECM Peak
Stage (ft)
RECM Peak
Stage (ft)
2.33 3.18 3.18 0.00 2.33 3.54 3.73 0.19
5 3.82 3.80 -0.02 5 4.59 4.91 0.32
10 4.46 4.46 0.00 10 5.16 5.08 -0.08
25 4.75 4.74 -0.01 25 5.23 5.12 -0.11
50 5.20 5.19 -0.01 50 5.37 5.26 -0.11
100 5.40 5.38 -0.02 100 5.48 5.40 -0.08
24-hr
Design
Storm
Frequency
(Year)
TABLE A: ECM vs RECM PEAK STAGES
Node 922104
S Side of 4TH AVE SE
(Upstream)
Node 922102
N Side of 4TH AVE SE
(Downstream)
Difference in Peak
Elevation
(ft)
24-hr
Design
Storm
Frequency
(Year)
Difference in Peak
Elevation
(ft)
Photo 3.2. Broken driveway retaining wall at D/S culvert
Photo 3.3. Eroding Endwall and Asphalt
Pavement (North Side)
The results indicate that there are no significant changes between the ECM and the
RECM. The The peak stage difference in the mean year and 5 year storm 24 hr storm events at the upstream section of the culvert is due to the smaller cross section area of the culvert as reported in the survey (48”x68” CMP) and the size used in SWMM (4’x6’
CMP).
The See Figure 3.1 for the SWMM5 Little Manatee Watershed Connectivity (ECM)
Nodal Connectivity Map
IV. PROPOSED CONDITIONS
The 4th Ave SE culvert replacement project proposes to replace the existing 43”x68”
CMP with 43”x68” ERCP. The proposed culvert will also be lengthened to meet minimum clear zone requirements. The existing ditch will be regarded to accommodate the new headwall placements.
The project’s link, proposed culvert P922104a, was modified to represent the proposed
43”x 68” ERCP. See Figure 3.2 for SWMM5 Proposed Conditions Model (PCM) nodal connectivity.
The existing 12” RCP driveway culvert P9221041 is also proposed to be upgraded to
14”x23” ERCP.
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.
RECM PCM RECM PCM
2.33 3.18 3.18 0.00 2.33 3.73 3.67 -0.06
5 3.80 3.81 0.01 5 4.91 4.83 -0.08
10 4.46 4.46 0.00 10 5.08 5.08 0.00
25 4.74 4.74 0.00 25 5.12 5.11 -0.01
50 5.19 5.19 0.00 50 5.26 5.26 0.00
100 5.38 5.38 0.00 100 5.40 5.40 0.00
RECM PCM RECM PCM
2.33 3.08 3.08 0.00 2.33 4.01 3.98 -0.03
5 3.65 3.66 0.01 5 5.06 4.99 -0.07
10 4.29 4.29 0.00 10 5.30 5.30 0.00
25 4.57 4.57 0.00 25 5.36 5.36 0.00
50 5.02 5.02 0.00 50 5.45 5.45 0.00
100 5.21 5.21 0.00 100 5.58 5.58 0.00
24-hr
Design
Storm
Frequency
(Year)
Difference in Peak
Elevation
(ft)
24-hr
Design
Storm
Frequency
(Year)
Node 922100
Downstorm of Little
Manatee River
TABLE B: PRE/POST-CONDITION
PEAK STAGE COMPARISON
24-hr
Design
Storm
Frequency
(Year)
Difference in Peak
Elevation
(ft)
24-hr
Design
Storm
Frequency
(Year)
Difference in Peak
Elevation
(ft)
Node 922102
N Side of 4TH AVE SE
(Downstream)
Node 922104
S Side of 4TH AVE SE
(Upstream)
Difference in Peak
Elevation
(ft)
Node 922110 South of
4TH Ave SE
(Upstream)
Based on the results, the proposed improvements will not cause any significant adverse impact tot the upstream and downstream nodes. The results show some minor improvements at the upstream section of the culvert.
RECM PCM
2.33 3.73 3.67 -0.06
5 4.91 4.83 -0.08
10 5.08 5.08 0.00
25 5.12 5.11 -0.01
50 5.26 5.26 0.00
100 5.40 5.40 0.00
TABLE B: PRE/POST-CONDITION
PEAK STAGE COMPARISON
Difference in Peak
Elevation
(ft) Peak Stage (ft)
Node 9221041
4th Ave Driveway
24-hr
Design
Storm
Frequency
(Year)
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 to 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: 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.
SWMM5 MODEL
(RECM and PCM submitted separately)
File details come from the government source that posted it. Updated .