Table 28.12.020: Stormwater Management Manual Drainage
Report Checklist
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---|---|---|---|---|---|
Instructions:
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1.
|
Applicant to identify with a check-mark if information is provided
with report. If applicant believes information is not required, indicate
with “n/a” and attach separate sheet with explanation.
| |||
2.
|
The reviewer will determine if information labeled “n/a”
is required and whether information must be submitted.
| ||||
3.
|
Those items noted with an asterisk are not typically required
for conceptual/preliminary report. Applicant shall confirm this with
local jurisdiction.
| ||||
4.
|
Submit three copies of report and include copy of check list
bound with report.
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TITLE PAGE
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A.
|
Type of report (conceptual/preliminary or final drainage report).
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B.
|
Project name.
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C.
|
Preparer name, firm, address, number, and date.
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D.
|
Professional Engineer’s seal of preparer.
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E.
|
Certifications (see GJMC § 28.12.070).
| ||||
I.
|
INTRODUCTION
| ||||
A.
|
Background
| ||||
|
1.
|
Identify report preparer and purpose.
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2.
|
Identify date of letter with previous County comments.
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B.
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Project Location
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|
1.
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Identify Township, Range, and Section.
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2.
|
Identify adjacent street and subdivision names.
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|
3.
|
Reference to General Location Map.
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C.
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Property Description
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|
1.
|
Identify area in acres of entire contiguous ownership.
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|
2.
|
Describe existing ground cover, vegetation, soils, topography
and slopes.
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|
3.
|
Describe existing drainage facilities, such as channels, detention
areas, or structures.
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|
4.
|
Describe existing irrigation facilities, such as ditches, headgates,
or diversions.
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5.
|
Identify proposed types of land use and encumbrances.
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D.
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Previous Investigations
| ||||
|
1.
|
Identify drainage master plans that include the project area,
including floodplain studies.
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|
2.
|
Identify drainage reports for adjacent development.
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II.
|
DRAINAGE SYSTEM DESCRIPTION
| ||||
A.
|
Existing Drainage Conditions
| ||||
|
1.
|
Describe existing topography and provide map with contours extending
a minimum of 100 feet beyond property limits.
| |||
|
2.
|
Identify major drainageway or outfall drainageway and describe
map showing location of proposed development within the drainageways.
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|
3.
|
Identify pre-developed drainage patterns and describe map showing
predeveloped sub-basins and concentrated discharge locations. Provide
calculations of pre-developed peak flows entering and leaving the
site.
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B.
|
Master Drainage Plan
| ||||
|
1.
|
Describe location of the project relative to a previously prepared
master drainage plan, including drainage plans prepared for adjacent
development.
| |||
C.
|
Off-Site Tributary Area
| ||||
|
1.
|
Identify all off-site drainage basins that are tributary to
the project.
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|
2.
|
Identify assumptions regarding existing and future land use
and effects of off-site detention on peak flows.
| |||
D.
|
Proposed Drainage System Description
| ||||
|
1.
|
Identify how off-site stormwater is collected and conveyed through
the site and ultimately to the receiving water(s).
| |||
|
2.
|
Identify sub-basins and describe, in general terms, how on-site
stormwater is collected and conveyed through the site for each location
where stormwater is discharged from the site.
| |||
*
|
3.
|
Describe detention volumes, release rates and pool elevations.
| |||
*
|
4.
|
Identify the difference in elevation between pond invert and
the groundwater table.
| |||
|
5.
|
Describe how stormwater is discharged from the site, including
both concentrated and dispersed discharges and rates.
| |||
|
6.
|
Describe stormwater quality facilities.
| |||
*
|
7.
|
Describe maintenance access aspects of design.
| |||
*
|
8.
|
Describe easements and tracts for drainage purposes, including
limitation on use.
| |||
E.
|
Drainage Facility Maintenance
| ||||
*
|
1.
|
Identify responsible parties for maintenance of each drainage
and water quality facility.
| |||
*
|
2.
|
Identify general maintenance activities and schedules.
| |||
III.
|
DRAINAGE ANALYSIS AND DESIGN CRITERIA
| ||||
A.
|
Regulations
| ||||
|
1.
|
Identify that analysis and design was prepared in accordance
with the provisions of this manual.
| |||
|
2.
|
Identify other regulations or criteria which have been used
to prepare analysis and design.
| |||
B.
|
Development Criteria
| ||||
|
1.
|
Identify drainage constraints placed on the project, such as
by a major drainage study, floodplain study or other drainage reports
relevant to the project.
| |||
|
2.
|
Identify drainage constraints placed on the project, such as
from major street alignments, utilities, existing structures, and
other developments.
| |||
C.
|
Hydrologic Criteria
| ||||
(If manual was followed without deviation, then a statement
to that effect is all that is required. Otherwise provide the following
information where the criteria used deviates from this manual.)
| |||||
|
1.
|
Identify developed storm runoff peak flows and volumes and how
they were determined, including rainfall intensity or design storm.
| |||
|
2.
|
Identify which storm events were used for minor and major flood
analysis and design.
| |||
|
3.
|
Identify how and why any other deviations from this manual occurred.
| |||
D.
|
Hydraulic Criteria
| ||||
(If manual was followed without deviation, then a statement
to that effect is all that is required. Otherwise provide the following
information where the criteria used deviates from this manual.)
| |||||
*
|
1.
|
Identify type(s) of streets within and adjacent to development
and source for allowable street capacity.
| |||
*
|
2.
|
Identify which type(s) of storm inlets were analyzed or designed
and source for allowable capacity.
| |||
*
|
3.
|
Identify which type of storm sewers which were analyzed or designed
and Manning’s n-values used.
| |||
*
|
4.
|
Identify which method was used to determine detention volume
requirements and how allowable release rates were determined.
| |||
*
|
5.
|
Identify how the capacity of open channels and culverts were
determined.
| |||
*
|
6.
|
Identify any special analysis or design requirements not contained
with this manual.
| |||
|
7.
|
Identify how and why any other deviations from this manual occurred.
| |||
E.
|
Variance from Criteria
| ||||
|
1.
|
Identify any provisions of this manual for which a variance
is requested.
| |||
|
2.
|
Identify pre-existing conditions which cause the variance request.
| |||
*IV.
|
POST-CONSTRUCTION STORMWATER MANAGEMENT. See Chapter 28.64 GJMC for requirements.
| ||||
Note:
|
This section of the final drainage report identifies additional
information required by Mesa County’s, City of Grand Junction’s,
and Town of Palisade’s, permit for stormwater discharges associated
with municipal separate storm sewer systems (MS4s), Permit No. COR-090000.
The final drainage plan and the construction SWMP (see Chapter 28.6
GJMC) meets the requirements of the MS4s permit. In general, this
section identifies permanent BMP practices to control the discharge
of pollutants after construction is complete.
| ||||
*A.
|
Stormwater Quality Control Measures
| ||||
*
|
1.
|
Describe the post-construction BMPs to control discharge of
pollutants from the project site.
| |||
*
|
2.
|
If compensating detention is provided, discuss practices to
address water quality from area not tributary to detention area.
| |||
*
|
3.
|
If underground detention is proposed, discuss how water quality
facilities will be provided on the surface.
| |||
|
4.
|
If proprietary BMPs are proposed, provide the justification and sizing requirements (see GJMC § 28.64.040).
| |||
*B.
|
Calculations
| ||||
|
1.
|
Provide methods and calculations for WQCV, sediment storage,
and water quality outlet structure.
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V.
|
CONCLUSIONS
| ||||
A.
|
Compliance with Manual
| ||||
|
Compliance with manual and other approved documents, such as
drainage plans and floodplain studies.
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B.
|
Design Effectiveness
| ||||
|
Effectiveness of drainage design to control impacts of storm
runoff.
| ||||
C.
|
Areas in Flood Hazard Zone
| ||||
|
Meet requirements of Floodplain Regulations: Mesa County Land Development Code, Section 7.13; GJMC § 21.07.010.
| ||||
D.
|
Variances from Manual
| ||||
|
Applicant shall identify any requested variances and provide
basis for approving variance. If no variances are requested, applicant
shall state that none are requested.
| ||||
VI.
|
REFERENCES
| ||||
|
Provide a reference list of all criteria, master plans, drainage
reports, and technical information used.
| ||||
TABLES
| |||||
|
Include copy of all tables prepared for report.
| ||||
FIGURES
| |||||
|
A.
|
General Location Map (See GJMC § 28.12.080(a))
| |||
|
B.
|
Floodplain Information
| |||
|
C.
|
Drainage Plan (See GJMC § 28.12.080(b))
| |||
|
D.
|
Other pertinent figures.
| |||
APPENDICES
| |||||
A.
|
DESIGN CHARTS
| ||||
|
1.
|
Provide copy of all design charts (i.e., tables, figures, charts
from other criteria) used for the report.
| |||
B.
| |||||
|
1.
|
Land use assumptions for off-site runoff calculations.
| |||
|
2.
|
Time of concentration and runoff coefficients for pre-existing
and post development conditions.
| |||
|
3.
|
Pre-developed hydrologic computations.
| |||
|
4.
|
Developed conditions hydrologic computations.
| |||
C.
|
HYDRAULIC CALCULATIONS
| ||||
|
1.
|
Capacity of existing channels, streets, storm sewers, inlets,
culverts and other facilities.
| |||
|
2.
|
Calculations for existing storm sewer and open channel.
| |||
|
3.
|
Irrigation ditch flows and ditch system capacity.
| |||
*
|
4.
|
Detention pond design (see Chapter 28.56 GJMC for requirements).
| |||
*
|
a.
|
Storage volume, release rates, and pool elevations for 10-year
and 100-year storm.
| |||
* |
b.
|
Outlet structure dimensions, orifice diameter, weir lengths,
pipe headwater and other data.
| |||
*
|
c.
|
Outlet velocity and energy dissipation requirements.
| |||
*
|
d.
|
Routing of outlet flows and emergency spillway flows.
| |||
*
|
5.
|
Street capacity calculations, if data in manual not used (see Chapter 28.44 GJMC).
| |||
*
|
6.
|
Storm inlet capacity calculations, if data in manual not used (see Chapter 28.44 GJMC).
| |||
*
|
7.
|
Storm sewer capacity calculations, if data in manual not used (see Chapter 28.44 GJMC).
| |||
*
|
8.
|
Channel capacity calculations, if data in manual not used (see Chapter 28.32 GJMC).
| |||
*
|
9.
|
Culvert capacity calculations (see Chapter 28.48 GJMC).
| |||
*
|
10.
|
Other hydraulic structure calculations (see Chapter 28.36 GJMC).
| |||
D.
|
STORMWATER QUALITY CALCULATIONS
| ||||
|
1.
|
Water quality capture volume (WQCV).
| |||
*
|
2.
|
Storage volume for sediment volume and pool elevations for WQCV.
| |||
*
|
3.
|
Outlet calculations for required area per row, diameter of individual
holes, number of holes per row, and number of holes per column.
| |||
|
CERTIFICATION – PROFESSIONAL ENGINEER’S
SEAL AND SIGNATURE
ACKNOWLEDGEMENTS
| ||||
Drainage Report checklist was prepared by:
|
Text shall be typed on eight-and-one-half-inch by 11-inch paper.
All pages, including appendices, shall be numbered in a fashion that
identifies the report (e.g., PDR-#). Text, tables, figures, charts,
calculations, and appendices shall be bound to form a formal report.
Drawings shall be included in a pocket attached with the report, but
shall not be smaller than 11 inches by 17 inches or larger than 24
inches by 36 inches in size. The report shall include a cover letter
presenting the conceptual/preliminary design for review and shall
be stamped and signed by an engineer licensed in Colorado.
|
Text shall be typed on eight-and-one-half-inch by 11-inch paper.
All pages, including appendices, shall be numbered in a fashion that
identifies the report (e.g., FDR-#). Text, tables, figures, charts,
calculations, and appendices shall be bound to form a formal report.
Drawings shall be 24 inches by 36 inches and included in a pocket
attached with the report. The report shall include a cover letter
presenting final design for review and shall be stamped and signed
by an engineer licensed in Colorado.
|
I hereby certify that this Final Drainage Report (plan) for the design of (Name of Development) was prepared by me
(or under my direct supervision) in accordance with the provisions
of the Stormwater Management Manual for the owners
thereof. I understand that the (local jurisdiction) does not and will
not assume liability for drainage facilities designed by others.
| |
__________________________
Registered Professional Engineer
State of Colorado No._________
(Affix Seal)
| |
I, (Name of Developer) hereby certify that the drainage facilities
for (Name of Development) shall be constructed according to the design
presented in this report. I understand that the (local jurisdiction)
does not and will not assume liability for the drainage facilities
designed and/or certified by my engineer. I understand that the (local
jurisdiction) reviews drainage plans but cannot, on behalf of (Name
of Development), guarantee that final drainage design review will
absolve (Name of Developer) and/or their successors and/or assigns
of future liability for improper design. I further understand that
approval of the Final Plat and/or Final Development Plan does not
imply approval of my engineer’s drainage design.
| |
_______________________
Name of Developer
______________________
Authorized Signature
|
___________________
Date
|
Acceptance of the final construction plans and final drainage
report are required prior to issuance of a permit.
|
Construction plans shall be prepared in accordance with sound
engineering principles, this manual and the Mesa County Land Development
Code for subdivision designs. Construction documents shall include
geometric, dimensional, structural, foundation, bedding, hydraulic,
landscaping, and other details as needed to construct the storm drainage
facility. The approved final drainage plan shall be included as part
of the construction document for all facilities affected by the drainage
plan. Construction plans shall be signed by a registered professional
engineer as being in accordance with the County approved drainage
report, drawings, and this manual. Requirements for construction plans
are outlined in the checklist in Table 28.12.090.
|
Table 28.12.090: Stormwater Management Manual Drainage
Plan Checklist
| ||||
---|---|---|---|---|
Instructions:
|
1.
|
Applicant to identify with a check-mark if information is provided.
If applicant believes information is not required, indicate with “n/a.”
| ||
2.
|
County will determine if information labeled “n/a”
is required and whether information must be submitted.
| |||
I.
|
EXISTING FACILITIES
| |||
|
A.
|
Contours at two-foot intervals, based on USGS datum. Contours
to extend at least 50 feet past property line.
| ||
|
B.
|
Location and elevation of USGS benchmarks or benchmarks referenced
to USGS.
| ||
|
C.
|
Property lines.
| ||
|
D.
|
Drainage easements.
| ||
|
E.
|
Street names.
| ||
|
F.
|
Major and minor channels and floodplains.
| ||
|
G.
|
A historic drainage plan including historic basin boundaries
and flow paths.
| ||
II.
|
PROPOSED FACILITIES
| |||
|
A.
|
Contours at two-foot intervals, based on USGS datum.
| ||
|
B.
|
Property lines.
| ||
|
C.
|
Drainage easements.
| ||
|
D.
|
Street names and grades.
| ||
|
E.
|
Right-of-way and easement.
| ||
|
F.
|
Finished floor elevations for protection from major storm runoff.
| ||
|
G.
|
Detention pond information:
| ||
|
1.
|
Location of each detention pond with site at 1" = 50' scale
or larger with two-foot contour intervals.
| ||
|
2.
|
Inlet and outlet structure, and trickle channel design details.
| ||
|
3.
|
Details of emergency spillway and channel.
| ||
|
4.
|
Landscape information, including side slopes, vegetation and
planting requirements.
| ||
|
5.
|
Details of water quality outlet structure.
| ||
H.
|
Channel information:
| |||
|
1.
|
Profiles with existing and proposed grades.
| ||
|
2.
|
Cross-sections on 100-foot stations showing existing and proposed
topography and required rights-of-way.
| ||
|
3.
|
Locations and size of all existing and proposed structures.
| ||
|
4.
|
Locations and profiles of adjacent utilities.
| ||
|
5.
|
Typical channel section and lining details.
| ||
I.
|
Storm sewer information:
| |||
|
1.
|
Alignment and location of manholes, inlets, and outlet structures.
| ||
|
2.
|
Profile of invert and pipe crown.
| ||
|
3.
|
Invert elevations at manholes and inlets.
| ||
|
4.
|
Lengths and grades between manholes and inlets.
| ||
|
5.
|
Locations and elevations of utilities adjacent to and crossing
storm sewer.
| ||
|
6.
|
Easement and other O&M access geometry.
| ||
|
7.
|
Outlet details, such as end sections, headwall and wingwalls,
erosion control, and vegetation.
| ||
|
J.
|
Street cross-sections with design 100-year flood depth.
| ||
|
K.
|
Other drainage related structures and facilities, including
underdrains and sump pump discharge lines.
| ||
|
L.
|
Other permanent BMP measures to control pollutant discharges
to the County’s MS4 system.
| ||
III.
|
HYDRAULIC AND HYDROLOGIC INFORMATION
| |||
|
A.
|
Routing and accumulative runoff peaks at upstream and downstream
ends of the site and at various critical points on-site for initial
and major storms. Inflow and outflow from each sub-basin shall be
shown for both initial and major storms.
| ||
|
B.
|
Street cross-sections showing 100-year flood levels.
| ||
|
C.
|
Major and minor channels and floodplains.
| ||
|
D.
|
Detention pond data:
| ||
|
1.
|
Release rates for 10- and 100-year storm events.
| ||
|
2.
|
Required and provided volumes for 10- and 100-year storm events.
| ||
|
3.
|
Design depths for 10- and 100-year storm events.
| ||
|
4.
|
Water quality capture volume and pool elevation.
| ||
E.
|
Channel data:
| |||
|
1.
|
Water surface profiles.
| ||
|
2.
|
Representative 100-year flow velocity and Froude number.
| ||
F.
|
Storm sewer data:
| |||
|
1.
|
Profile of water surface for design flow rate.
| ||
|
2.
|
Peak flows for design flow, two-year and 100-year storm events.
| ||
IV.
|
STANDARD NOTES
| |||
|
A.
|
No building, structure, or fill will be placed in the detention
areas and no changes or alterations affecting the hydraulic characteristics
of the detention areas will be made without the approval of the County.
| ||
|
B.
|
Maintenance and operation of the detention and water quality
areas is the responsibility of property owner. If owner fails in this
responsibility, the County has the right to enter the property, maintain
the detention areas, and be reimbursed for costs incurred.
| ||
|
C.
|
Detention pond volumes, all drainage appurtenances, and basin
boundaries shall be verified. As-built drawings shall be prepared
by a registered professional engineer prior to issuance of certificate
of occupancy for any structure within the development.
| ||
D.
|
Permission to reproduce these plans is hereby given to Mesa
County for County purposes associated with plan review, approval,
permitting, inspection and construction of work.
| |||
|
V.
|
PROFESSIONAL ENGINEER’S SEAL AND SIGNATURE
| ||
VI.
|
OTHER
| |||
|
A.
|
Horizontal and vertical control information and ties to existing
and proposed features.
| ||
ACKNOWLEDGEMENTS
| ||||
Drainage Plan checklist was prepared by: ___________________
|
ITEM
|
CERTIFICATION REQUIRED
|
COUNTY ACCEPTANCE REQUIRED
|
---|---|---|
Conceptual Drainage Report
|
Engineer
|
No
|
Final Drainage Report
|
Engineer and Developer
|
Yes
|
Construction Drawings
|
Engineer
|
Yes
|
Construction SWMP (see Chapter 28.6 GJMC)
|
Qualified EC Specialist
|
Yes
|
Record Drawings
|
Engineer
|
Yes
|