New York State Department of Transportation
PROJECT TITLE
DRAINAGE REPORT
For Non-DOT Projects
Prepared in Accordance With
Chapter 8 of the NYSDOT Highway Design Manual (HDM)
Prepared By:
Consulting Firm
Consultant Location
Date (Month and Year)
|PLACE P.E. STAMP |
Note: It is a violation of law for any person, unless they are acting under the direction of a licensed professional engineer, architect, landscape architect, or land surveyor, to alter an item in any way. If an item bearing the stamp of a licensed professional is altered, the altering engineer, architect, landscape architect, or land surveyor shall stamp the document and include the notation "altered by" followed by their signature, the date of such alteration, and a specific description of the alteration.
Table of Contents:
Cover………………..………………………………………………………...………………..………….1
Table of Contents….……………………………………………………..……….………………..…….2
Summary of Drainage Impacts…...……………………………………..……….………….................3
Background………………………………………………………………………………………….…...3
Hydrology…………………………………………………………………….….……………….……….5
Open Channels..…………………………………………………………….…………………..……….6
Culverts………...………………………………………………………………..………….…………….6
Storm Drainage Conveyance System(s)………………………………………………..……………..7
Erosion & Sediment Control & Stormwater Management………………...…………..……………..8
Special Considerations.....………………………………….………………...…………..……………..8
References…...……….....………………………………….………………................………………...9
Appendices:
- Appendix A - X
Summary of Drainage Impacts:
Highway drainage is an important consideration in the design of many projects. The term drainage is defined in several different ways, including the process of removing surplus groundwater or surface waters by artificial means, the manner in which the waters of an area are removed, and the area from which waters are drained. A project may alter the existing drainage. When this occurs, drainage features should be provided which protect the highway, adjacent landowners, and the traveling public from water, while maintaining water quality and protecting other environmental resources.
The project will fall under one of the following conditions. Include one of the following statements:
A. [This development will not increase water flow onto the State Highway system.]
B. [This development will increase water flow onto the State Highway system, however analysis shows the design flow will be adequately handled by the existing State Highway drainage infrastructure and will not negatively impact downstream properties and/or water bodies.]
C. [This development will increase water flow onto the State Highway system, and analysis shows that the existing State Highway drainage infrastructure is inadequate to accept the design flow. This report includes a discussion of improvements required to the State Highway drainage system to handle flows from the proposed development and ensure that they will not negatively impact downstream properties and/or water bodies.]
Complete Table 1 if statement B or C above apply (modify storm events and add Design Points if necessary)
TABLE 1 - STORMWATER SUMMARY
|Storm Event |Pre–Project Runoff (cfs) |Post–Project Runoff (cfs) |
|Design Point 1 |
|5 |x.xx |x.xx |
|10 |x.xx |x.xx |
|25 |x.xx |x.xx |
|50 |x.xx |x.xx |
Background:
Preliminary research should take place before conducting the first field trip in order to make the trip more productive:
1. Obtain available topographic information, including USGS quadrangles, county or municipal topographic maps or other recent surveys. Outline the drainage patterns and areas on a contour map.
2. Determine soil characteristics of each drainage area for the project. This information may be obtained from the NRCS County Soil Survey or from the Regional Geotechnical Engineer.
3. Check Highway Record Plans for the area. They can be used as a guide to size proposed structures.
Project Soils:
See Appendix D for the NRCS soils map within the project area. The following soil types and hydrologic groups are present within the project drainage area:
TABLE 2 – SOIL TYPE
|Soil Symbol, Name, % Slope |Hydrologic Group |Texture |Character |Erosion Hazard |% within |
|Range |(HSG) | | |Potential |project drainage area |
|DeA, Deerfield complex, 3 |B |Loamy fine |Moderately well |*Slight |27.5% |
|to 8 percent slopes | |sand |drained | | |
|Ud, Udipsamments, dredged |A |Loamy sand or |Excessively drained |*Slight to |53.3% |
| | |sand | |moderate | |
|WnB, Windsor Complex, 3 to |A |Loamy sand |Excessively drained |*Slight |12.1% |
|8 percent slopes | | | | | |
|WnD, Windsor Complex, 15 to|A |Loamy sand |Excessively drained |*Severe |7.1% |
|25 percent slopes | | | | | |
• Number of different soil series and hydrologic soil groups
• Brief description of each series
EXAMPLE: There are three different soil series and two different hydrologic soil groups within the project drainage area. The largest soil series within the project area is the Udipsamments soil, which is made up of material dredged from Saratoga Lake. It is typically loamy sand or sand with layers of silty material or gravel at varying depths. Depth to bedrock is greater than 60 inches and depth to seasonal groundwater is more than 6 feet. The Deerfield complex (DeA) makes up the next largest portion of the area of disturbance. It is a loamy fine sand formed on glacial outwash plains and terraces. It is very deep, moderately well drained and the topography within this series is generally undulating. Depth to bedrock is greater than 60 inches and depth to water table is between 1.5 and 3 feet. The Windsor complex contains the remaining two soil types, WnB and WnD with the first characterized by undulating terrain and the second hilly terrain. Both subseries are loamy sand, excessively drained and formed on glacial outwash plains, kames and terraces. Depth to bedrock is greater than 60 inches and depth to seasonal groundwater is more than 6 feet.
*(The erosion hazard indicated in the table above was originally a consideration for the forestry industry, and indicates the susceptibility of a particular soil to erode in a fully exposed condition. The Department is utilizing this information to indicate areas of the project which may be of critical concern to the contractor during storm events).
Construction History:
• The existing drainage system(s) were constructed in [enter year(s)]
• Project Dnumber(s) for previous State contracts [list Dnumber(s)]
• The existing drainage facilities are [closed drainage, open ditches with driveway pipes, curb and gutter sections]. The pipes are predominately made from [HDPE, corrugated steel, reinforced concrete, PVC]
EXAMPLE: The existing drainage conveyance systems were constructed in the 1960’s under state highway contract RC 60-01. Roadside ditches drain towards the south and flow through corrugated metal pipes (generally 18” diameter) under driveways. There is a 36” RCP cross culvert under SR 14 approximately 0.2 miles south of the proposed driveway location that directs drainage off the State Highway ROW to a stream.
Field Observations/ Research:
After the preliminary research has been completed, and preliminary flow rates calculated, the initial field trip should be taken. (Be sure to bring a camera, take lots of pictures, and always try to include a person or other item of known size in the picture to act as a visual scale.) The main items to be investigated are:
1. Drainage patterns and drainage areas.
2. Land use.
3. Soil types.
4. Existing and previous flood conditions.
5. Location of natural and man-made detention features.
• Field collected data [verified OR exhibited discrepancies] with the record plans.
• Ongoing drainage problems [were discovered OR were confirmed not to exist] as a result of outreach to the local DPW or nearby property owners.
• Recent improvements [were discovered OR were not found] which may not be accounted for in the survey information.
• Include photographs of special areas of interest.
• Existing drainage features [will be retained and connected to proposed features OR will not be effected by proposed features]. The methods used to connect existing and proposed drainage are [explain].
EXAMPLE: On 6-5-09 a visual inspection was conducted. Runoff from approximately the intersection of SR 14/CR 72 is collected in roadside ditches and directed to the south. Where driveways cross the ditch, 18” corrugated metal pipes were installed. Most of the driveway culverts are 25%-50% clogged. Pipes that are clear of debris show deterioration and rusty perforated inverts.
The ditch has been filled in and a 24” RCP installed at the Yankee One Dollar store location. Two drainage structures were installed at the edge of their parking lot which connect into the ditch south of the parking lot via 12” SICPP.
Discussions with the NYSDOT Seneca county residency have not brought attention to any significant pre-existing drainage problems noted by maintenance forces or history of public complaint. During the field inspection some residents approached the inspector and indicated that the roadside ditches are generally full of standing water. They would like them regraded to drain. The residents did not recall any history of the ditches overflowing onto their property.
Hydrology:
Several methods for determining flow rates are listed in items 1 through 4 below. Methods 1 and 2 are based upon rainfall effects and do not consider snowmelt. In some areas, runoff from snowmelt will regularly exceed peak events due to rainfall. Each flow rate determination method is unique. Users should be familiar with each method, and be able to select the most appropriate method for each location and situation.
Recommended methods include:
1. Rational Method. Computes a peak discharge.
2. Modified Soil Cover Complex Method ("Urban Hydrology for Small Watersheds", NRCS TR-55, is the basis for this method). Computes a peak discharge directly using a formula and by plotting a hydrograph.
3. Regression Equations. Computes a peak discharge.
4. Historical Data.
The design flood frequencies provided in Table 8-2 are recommended for use with the Rational Method, the Modified Soil Cover Complex Method, and the regression equations. The design flood frequency is the recurrence interval that is expected to be accommodated without exceeding the design criteria for the open channel, culvert, or storm drainage system.
[pic]
1. The values in this table are typical. The selected value for a project should be based upon an assessment of
the likely damage to the highway and adjacent landowners from a given flow and the costs of the drainage
facility. Note: 100-year requirements must be checked if the proposed highway is in an established
regulatory floodway or floodplain.
2. The check flow, used to assess the performance of the facility, should be the 100 year storm event.
3. Relocated natural channels should have the same flow characteristics (geometrics and slope) as the
existing channel and should be provided with a lining having roughness characteristics similar to the existing
channel.
4. Including lining material.
5. As per 23CFR650A, and Table 1-1 of HDS 2, a 50-year frequency shall be used for design at the following
locations where no overflow relief is available:
a. sag vertical curves connecting negative and positive grades.
b. other locations such as underpasses, depressed roadways, etc.
6. A design flood frequency of 10 or 25 years is acceptable if documented in the Design Approval Document,
and when identified after design approval, in the drainage report. A design flood frequency of 10 or 25 years
should be used in the design of driveway culverts and similar structures.
7. Use a 25-year frequency at the following locations where no overflow relief is available:
a. sag vertical curves connecting negative and positive grades.
b. other locations such as underpasses, depressed roadways, etc.
• The watershed areas were delineated using [DTM’s, DEM’s, contours, field inspection]. See Appendix C for Subcatchment Maps.
• The hydrologic analysis method used is [TR-55, Rational Method, Regression Equations, Historical Data]
• The design storm from NYSDOT Highway Manual Chapter 8, Table 8-2 used for analysis is [Explain]
• The rainfall information selected (IDF curve) is [Explain]. The reasoning for choosing the selected rainfall information is [Explain].
• The computer software used in the analysis is [Explain].
EXAMPLE: Drainage basins were delineated utilizing a combination of photogrammetric survey, USGS topographic maps, and site reconnaissance. The contributing drainage area varies within the project, the northern portion adjacent to the SR 14 is predominantly moderate slope residential neighborhoods with 1 acre lots. The southern portion of the drainage area is flatter with some commercial/industrial development. Because of the size of all contributing basins, smaller than 80 hectares (197 acres), the rational method was used to develop peak discharge conditions (ref HDM 8.3.2.4). Contributing drainage basins to each inlet or culvert opening were delineated with the use of survey data available and USGS topographic mapping when outside of survey limits. Runoff coefficients used are consistent with HDM Table 8-3, times of concentration were computed, and in most cases the minimum of 5 minutes was used (HDM 8.3.2.4). A 10-year design storm frequency for principal arterials was selected in accordance with HDM Table 8-2. The closest IDF curve available for the area was the Seneca County, NY curve developed by the NYSDOT main office in Albany utilizing HEC 12 software (refer to appendix A). Bentley Storm and Sanitary computer software was used to develop peak flows.
Open Channels:
The open channels that will be affected by the project are located [Explain].
• The scope of work includes [regrading existing channels, converting open channels to closed drainage, lining existing channels with stone fill, installing rolled erosion control products]
• Provide a brief analysis of the capacity and expected flow in the channels.
• Channels to be stone lined will use [fine, light, medium, heavy] size stone based on the expected channel velocity of [Explain].
• Channels to be lined with RECP’s will use [select appropriate item from spec section 209-3.10]
EXAMPLE: Drainage will be maintained in open channels along the East and West sides of SR 14. The channel outside the proposed development is in good condition with 1:4 side slopes and is traversable by errant vehicles. While the watershed boundaries remain unchanged, the volume and rate of runoff will increase as a result of the proposed parking lot installation. The channel is adequately sized, has a slope of 1% or less, and does not warrant stone lining.
Culverts:
Identify any culverts that will be affected by the project (rehabbed or replaced).
• The scope of work includes [cleaning existing culverts, lining existing culverts to extend their service life, replacing existing culverts, installing culverts in new locations].
• Provide a brief analysis of the capacity and expected flow in the culverts.
• The inlet and outlet treatments will include [galvanized end sections, concrete headwalls, stone aprons].
• The software used to size culverts is [HY-8, HydroCADD, TR-55].The software output files are provided in appendix B.
EXAMPLE: There are numerous 18” CMP driveway culverts in the ditch line downstream of the proposed development. These were analyzed for capacity and found to be adequate for the ditch flow (including the additional flows from the proposed development). HY-8 capacity analysis is included in Appendix B. A proposed 18” SICPP culvert will be installed under the proposed driveway. It will be installed with metal traversable end sections with bars at the inlet and outlet. Light stone fill will be placed at the outlet to eliminate any scour caused by higher velocity flows through the smooth pipe exiting into the grassed ditch.
Storm Drainage Conveyance System(s):
For each existing and/or proposed stormwater drainage network address the following items:
• The limits of the [existing/proposed] network are [street names, stations, landmarks as appropriate].
• List structures to either remain, be rehabilitated, or replaced.
• Include pipe rehabilitation techniques and new proposed pipe materials.
• Discuss hydrologic analysis of system and any areas of concern.
• To build the proposed network, the work zone will have to include phases to allow installation of the proposed drainage features. The sequence of construction is [Explain].
• The analysis software output file is attached in Appendix B.
• If the proposed closed drainage system will connect to a State closed drainage system, the requirements of HDM Chp. 8, Section 8.2.3.2 must be met.
EXAMPLE: A closed storm drainage system will be installed in the proposed parking lot. It will consist of two inlet structures in the center portion of the parking area. The surrounding asphalt will be graded to drain to these two structures. These will be piped to the existing roadside ditch with 12” diameter SICPP. A metal end section will be installed at the outlet into the ditch. All construction will be on private property and will not require lane or shoulder closures on the State Highway.
[pic]
Figure 3: Example Stormwater Reconstruction Areas and Discharge Locations
Erosion & Sediment Control & Stormwater Management:
Erosion and sediment control is any temporary or permanent measure taken to reduce erosion, control siltation and sedimentation, and ensure that sediment-laden water or wind does not leave the site. Guidelines for providing erosion and sediment control are discussed in Section 8.8.2.1. The E&SC plan resulting from these guidelines is discussed in Section NYSDOT HDM 8.8.2.2.
Note: The guidance in Sections 8.8.2.1 and 8.8.2.2 is based on Attachment 4.3.A of EPM Chapter 4.3
The following is recommended guidance:
1. Preserve the existing vegetative groundcover on the project site as much as possible to protect the soil surface and limit erosion.
2. Sediment control practices/measures, where necessary, should be designed to protect the natural character of rivers, streams, lakes, coastal waters, wetlands, or other waterbodies on-site and minimize erosion and sedimentation off-site from the start of land disturbance activities to establishment of permanent stabilization.
a. The off-site impacts of erosion and sedimentation related to land clearing, grading, and construction activities should not be any greater during and following land disturbance activities than under pre-development conditions.
b. Pursuant to Part 700 et seq. of Title 6, Chapter X of NYCRR:
1. Toxic and other deleterious substances shall not be discharged in amounts that will adversely affect the taste, color or odor thereof, or impair the waters of the state for their best (classified) usages,
2. Suspended, colloidal, and settleable solids shall not be discharged in amounts that causes substantial visible contrast to natural conditions, or causes deposition or impairs the waters for their best (classified) usages.
The project will fall under one of the following conditions. Include one of the following statements:
A. The project will be subject to NYSDEC general permit GP-0-10-001, which covers State Pollution Discharge Elimination Systems (SPDES). Because of this the project will be obligated to have a Stormwater Pollution Prevention Plan (SWPPP). For a detailed description of proposed temporary erosion and sediment control and permanent water treatment plans and practices please refer to the projects SWPPP. [For project disturbances > 1 acre]
OR
B. The project will follow the Erosion & Sediment Control provided in NYSDOT Highway Design Manual, Chapter 8.2 [For project disturbances < 1 acre]
Refer to the Erosion & Sediment Control plans for proposed temporary on-site Erosion Control measures.
Special Considerations:
• Briefly discuss any special environmental concerns (wetlands, stream temperature considerations, critical habitat, etc.) which influenced the drainage design.
EXAMPLE: The presence of wetlands on the north side of the proposed driveway between SR 14 and the proposed parking area influenced the site grading and required drainage to be directed to the south side of the proposed driveway.
References:
Highway Design Manual, Chapter 8, NYSDOT, 50 Wolf Road, Albany, NY 12232.
Standard Specifications, Construction and Materials, NYSDOT, 50 Wolf Road, Albany, NY 12232.
Hydraulic Engineering Circular No. 22, 2nd Edition, Urban Drainage Design Manual, August 2001, FHWA
Environmental Assessment Form [Long Form] OR [Short Form]
Record Plans: List appropriate Contract Plan set Dnumbers.
APPENDIX A
RAINFALL INFORMATION
IDF TABLE
APPENDIX B
NETWORK ANALYSIS
(Provide separate appendix for each independent storm drainage system or culvert)
APPENDIX C
SUBCATCHMENT MAPS
DRAINAGE PLANS
DETAILS
DRAINAGE NOTES
APPENDIX D
NRCS SOIL MAP
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DISCHARGE A
From Proposed Parking Lot to Ditch
................
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