2023-05-18 V. A. 23-001-TRC Letter re: Addtl Info Needed dated 03/31/23G&W) -
ENGINEERING
March 31, 2023
City of Okeechobee
Job No.: FL22024 - Glenwood
Subject: 23-001-TRC RAI Engineering Review
Dear Reviewer:
Below are responses to the Request for Additional Information based on the Engineering Review
Comments from January 19, 2023, for the above referenced permit application. The following
conditions are in regular type and responses are in italics.
Sec 78-36 — Sidewalks, driveways, and pedestrian access.
1. Provide typical design width on plans for sidewalks. Provide cross walk striping details
and detectable warning strips for proposed sidewalks.
Plans have been updated to include dimensions, striping details and detectable
warning strips for proposed sidewalks.
2. Address potential drop from sidewalk crossing to existing inlet at corner of NE 3rd AVE
and NE 4th ST.
According to the 2018 FDOT Greenbook, we are neither 10" lower within 2' at 3:1
slope (8 ") or 60" with a slope greater than 2:1, so we should meet this criteria.
3. Provide for Sidewalk location in Typical Section B-B. Include provision for minimum
clear graded area to avoid edge drop off to proposed swale.
Typical Section B-B has been updated to clarify the clear graded area so that there
will be no edge drop off into the proposed Swale.
Sec. 86-182 — (e)
4. Common detention areas for subdivision should be depicted as "general purpose areas"
outside of the proposed lots.
The detention areas are covered by a drainage easement within the proposed
subdivision and would be apart of the HOA duties, if ever subdivided.
209 NE 2nd Street, Okeechobee, FL 34972
Phone: (863) 824-7644 Cell: (863) 634-0194
Email: sdobbs@stevedobbsengineering.com Website: www.SteveDobbsEngineering.com
FL22024 Glenwood City of Okeechobee TRC RAI, Page 2
5. Provide locations on plan view of sheets 301-C302 for typical cross section A -A
Section A -A has been depicted on the plan sheets.
Sec. 8c-185 — Wastewater and water
6. Provide horizontal dimensions between proposed water and sewer mains.
Plans have been updated to show dimensions between proposed water and sewer
mains.
7. Provide additional details and criteria for proposed sewer design including lift station
details.
Additional details have been added for the proposed sewer design including the lift
station details.
8. Manhole details are provided in details; however, manholes are not provided in the
design. Please address.
The manhole detail has been removed from the plan set.
9. Provide proposed sanitary sewer easement for maintenance of system on future lots.
The easement has been added to the plan.
10. Provide force main design from lift station to point of connection to existing system.
The design has been added to the plans.
11. Proposed sewer mains appear to be in conflict with proposed landscape buffers.
The sewer line will be below the landscape buffers with cleanouts every 75" this
should not be in conflict with the landscape buffer.
12. Does proposed 8" water main connect to existing 6" water main on NE 4th Street?
Plans have been updated to show the detail of the proposed connection of the water
main on NE 4rh Street.
13. Fire Hydrant at NE 3rd AVE and NE 5th Street appears to be located within proposed
sidewalk. Please address.
Fire Hydrant location has been adjusted on the update plans.
14. Will duplex/2 family buildings need separate water meters?
Each duplex will have 2 water meters, one for each side of the building. This will
provide for best service to each unit.
FL22024 Glenwood City of Okeechobee TRC RAI, Page 3
15. Provide details for proposed water service connections to 16" water main on NE 2nd
Ave
The details have been added.
16. Provide details for water main crossing of NE 4th ST. (Direction bore, jack and bore,
casing, open cut with pavement restoration, horizontal separation from existing storm, etc
These details have been added.
17. Prior to construction commencement, provide a sewage collection/transmission system
construction permit from Florida Department of Environmental Protection and approval
from local sewer authority.
Prior to construction we will provide the copy of the approved construction permit
from the Florida Department of Environmental Protection and approval from
Okeechobee Utility Authority.
18. Prior to construction commencement, provide a water main extension construction
permit from Florida Department of Environmental Protection and approval from local water
authority.
Prior to construction we will provide the copy of the approved construction permit
from the Florida Department of Environmental Protection and approval from
Okeechobee Utility Authority.
Sec. 86-184 — Bridges and culverts.
19. Proposed Driveway culverts on NE 2nd Ave appear to conflict with existing 16" water
main.
The culverts have been relocated.
20. Proposed culverts on south side of NE 4th street appear to conflict with existing 5' storm
drain. Please address. Have alternate designs to connect to 5' storm drain been considered?
Provide invert and end treatment details for control structure connections to proposed
roadside swales on NE 4th Street.
The culverts
21. Provide minimum pipe coverage details per FDOT Standards for proposed CMP culverts
under proposed asphalt within public right-of-way.
The FDOT minimum clearance has been added to the plans.
FL22024 Glenwood City of Okeechobee TRC RAI, Page 4
22. Please provide details for culvert end treatments for culverts under proposed sidewalks.
Each should receive a MES that is in the details.
23. Provide additional details for proposed culverts and existing culverts at the corner of NE
5th ST and NE 3rd AVE
The details have been added to the plans.
24. Invert of proposed sidewalk culvert at NE 4th ST and NE 3rd AVE appears lower than
RIM elevation of existing storm drain of 18" RCP to south.
The inverts have been adjusted.
25. Proposed Driveway culvert on NE 4th street appears to conflict with existing storm
drain. Please address
The culvert has been adjusted.
26. Provide minimum pipe coverage details for proposed CMP culverts under proposed
asphalt within public right-of-way
Not sure if this is a duplicate comment, but please see item 21.
Sec. 34-2 — Fire hydrants.
27. Provide correspondence from Fire Marshall that the location and number of fire hydrants
as proposed are sufficient for the development.
The Fire Reviewer was at TRC and said the placement of the fire hydrants was
sufficient for the project.
Sec. 78-101— Requirements.
28. Please ensure that the placement of the silt fence follows the requirements of the
"Florida Stormwater, Erosion and Sediment Control Inspector's Manuals".
The silt fence has been relocated.
29. The written report states that pavement areas will pass through the dry detention areas.
Please confirm that unpaved areas will pass through the dry detention areas as well. (The
Storm CAD model appears to indicate that all water from each of the developed blocks will
be routed through the stormwater pond.)
Each block will be surrounded by a perimeter berm that will ensure all water from
impervious and pervious areas will pass through the dry detention area.
30. Please indicate how site grading and or drainage infrastructure will route water to the
ponds.
Each parking area is graded to shed water away from the driveway so the water will
FL22024 Glenwood City of Okeechobee TRC RAI, Page 5
be captured inside the perimeter berm of each block and swales on each property line will
ensure the water will be directed to the dry detention area.
31. The control elevation for BLOCK 110 is listed as 23.0 and the proposed pond bottom
elevation is listed as 23.33, SFWMD requires a dry pond bottom to be 1' higher than the
control elevation for the site. Please address.
The SFMWD required the bottom of the pond to be I 'above the wet season water
table which it is the remainder of the volume would be considered retention, but with
such a small distance the system will recover to wet season water table within the 12
day recovery period.
32. The control elevation for BLOCK 121 is listed as 24.0 and the proposed pond bottom
elevation is listed as 24.33, SFWMD requires a dry pond bottom to be 1' higher than the
control elevation for the site. Please address.
The SFMWD required the bottom of the pond to be 1 'above the wet season water
table which it is the remainder of the volume would be considered retention, but with
such a small distance the system will recover to wet season water table within the 12
day recovery period.
33. Under the allowable discharge calculation on the second page of the report pdf, the
Block 121 project acreage is listed as 2.20 acres. Total Basin Acreage on sheet 6 of your
drainage report lists the total Basin Acreage as 2.17 acres. Please clarify.
These area now match in each area of the report.
34. At the bottom of the second page in the drainage report is a statement that says "Since
the proposed water quality system is dry detention, the volume required is 100% of the
calculated volume." Please be advised that the dry pond water quality volume requirement
is 75% of the requirement for water quality being provided by a wet pond.
This has been corrected.
35. Section B Water Quantity on page 3 of the drainage report states "The actual maximum
discharge rate for the 10-year, 72-hour storm event was calculated and shown below, which
is within tolerance of the maximum allowable peak rate. To demonstrate conformance to
this criterion, the proposed project was flood -routed using WaterCAD." Was this referring
to the 25-year event instead?
This has been corrected.
36. Nutrient Loading: Please provide a site -specific pollutant loading analysis. If retention
is required to meet pollutant loading goals, please ensure retention areas are compliant with
a 72 hour drawdown requirement.
Nutrient loading analysis from the BMPTrains model has been added to the
drainage calculations.
37. Please demonstrate the tailwater assumptions used in the WaterCAD model. Consider
that Block 110 Swale as an invert elevation of 23.3 and an eop elevation of 25.7 within the
vicinity of CS-1.
FL22024 Glenwood City of Okeechobee TRC RAI, Page 6
I understand the concern, but even of the dry detention area does not start to drain
until hour 72, which would most likely be the peak tailwater elevation and would
recover quickly with full culvert discharge and no indication of perched water tables
in the vicinity, the dry detention area would start to discharge at hour 72 and if you
add the discharge from the beginning of the discharge at hour 45 and add it onto the
end of the recovery at hour 90, the dry detention area would still recover by hour
117, which is still well within the SFWMD 288 hour recovery time.
38. Please demonstrate the tailwater assumptions used in the WaterCAD model. Consider
that Block 121 Swale as an invert elevation of 24.3 and an eop elevation of 25.8 within the
vicinity of CS-2.
I understand the concern, but even of the dry detention area does not start to drain
until hour 72, which would most likely be the peak tailwater elevation and would
recover quickly with full culvert discharge and no indication of perched water tables
in the vicinity, the dry detention area would start to discharge at hour 72 and if you
add the discharge from the beginning of the discharge at hour 45 and add it onto the
end of the recovery at hour 90, the dry detention area would still recover by hour
117, which is still well within the SFWMD 288 hour recovery time.
If you should have additional question or require more information, please do not hesitate to contact
me.
Sincerely,
Steven L. Dobbs, P. E.
President