1/27/06
Local Jurisdictions Questionnaire
Urban Stormwater Management Study
The technical study team appreciates you taking the time to provide the information
requested and filling out this questionnaire. Please make an effort to fully complete this
questionnaire. Coordination with other departments within your organization may be
required for completion. There are several requests for documentation of the policies,
criteria and regulations governing stormwater management and drainage within your
jurisdiction. Please provide a copy of the manuals, resolutions, ordinances, regulations,
etc. that apply. If the information requested in the following questionnaire is available in
a manual or other document, please indicate in which chapter and/or page it is located.
If any problems or questions arise, please do not hesitate to contact Al Flores at (713)
527-6365 or Ranney McDonough at (713) 975-9990.
A.
General Information and Document Request
1.
Please provide the following information for the primary contact person:
a. Name: James E. Williams, P. E.
b. Title:
Director of Community Development
c. Address: 101 Pennsylvania Avenue
Webster, Texas 77598
2.
d. Phone:
281-332-1826
e. Email:
jwilliams@cityofwebster.com
What are the primary flooding issues in your jurisdiction?
Street flooding and flooding from Clear Creek. The City of Webster is
within the Clear Creek Watershed, with much of the southern portion of
the City within the floodplain. A 107-00-00 and A 109-00-00 channels
serving the City are located downstream of IH 45 and are generally
adequate to convey the 100-year flows within the banks, except the lower
reaches which are within the surge of Galveston Bay. A 108-00-00 is little
more than a roadside ditch of SH 3 and unimproved downstream of SH 3.
A 111-00-00 is the channel that gives the City development concerns, as
much of the lower reach of the channel is located within the City.
3.
Describe or list the official documents that contain policies, ordinances,
regulations, and/or criteria relating to stormwater management in your
jurisdiction (e.g. floodplain ordinances, building codes, subdivision
regulations, drainage criteria manual) and include the date of publication or
adoption. Please include a copy or refer to the online location of each
ordinance or code with your questionnaire. If the design criteria manual is not
the Harris County Flood Control District “Policy, Criteria & Procedure
Manual”, City of Houston Design Manual, Harris County Regulations or
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TxDOT Hydraulic Design Manual, please provide one (1) copy for our
information.
City of Webster Code of Ordinances, Chapter 42 Floods
www.cityofwebster.com
4.
Does your community have a flood control, drainage or storm sewer Master
Plan? If so, please provide a copy and answer the following questions:
No. The City currently has maps outlining detention requirements for
development within the City. The maps were developed to deal
primarily with localized street and storm sewer protection against
proposed development impacts. Proposed development outfalling
directly into HCFCD channels are required to gain approval from
HCFCD, including detention requirements.
a. When was the Master Plan established and adopted?
b. How is the Master Plan being used in your community?
5.
Does your community participate in the National Flood Insurance Program
(NFIP)? If so, please answer the following questions:
Yes
a. Has your community adopted standards in excess of the minimum NFIP
requirements? If so, please briefly describe.
Yes; the City of Webster has a 12" freeboard requirement
b. What is the Community Rating System (CRS) classification for your
community?
Ten (10)
B.
Drainage Policy
6.
Does your community have a finished floor slab elevation requirement? If so,
please answer the following questions:
Yes
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a. What is the requirement?
All floor slabs must be a minimum of 6" above the curb of the street
b. Is it different inside or outside the floodplain?
Inside the floodplain, City of Webster has the 12" freeboard
requirement; this could possible exceed 6"above the curb.
c. Do you have finished floor slab elevation information (i.e., structure,
location, elevation, datum, date elevation determined)?
Yes, City of Webster has elevation certificates for those structures
located within the floodplain.
7.
Is there a detention policy or regulations in your jurisdiction? If so, please
answer the following questions:
No written detention policy. The detention rates used are 0.20 acrefeet per acre for developing outfalling into a City storm sewer system
having designed capacity available. For other tracts, the rate is 0.45
acre-feet per acre. All other criteria is set to City of Houston and
HCFCD.
a. Is a proposed detention basin allowed to be located in the floodplain or
floodway?
Detention basins are permitted within the floodplain, however, any
development within the floodplain is carefully monitored for
compliance with FEMA requirements. Detention basins within the
floodway are reviewed on a case by case basis, and are seldom
allowed.
b. What is the minimum development size that is required to mitigate for the
impacts of development? Is the minimum size the same for commercial
and residential development?
There are no minimum size development requirements.
c. Do you have a regional detention program for mitigating existing flooding
or mitigating new development or both? If so, please answer the
following questions:
The City does not currently have regional detention basins unless
constructed for a small development.
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i. Is excess regional detention capacity available for new development?
Are impact fees assessed?
N/A
ii. Are there any restrictions (maximum development size) for use of the
regional storage?
N/A
8.
Is there a “No Rise” policy or regulation in your jurisdiction for projects built
in the floodplain? If so, please answer the following questions:
No, however, the City follows FEMA guidelines for development within
the floodplain.
a. What storm frequency or frequencies does the “No Rise” apply to?
N/A
b. What is the method for calculating the storage compensation required?
(e.g. modeling techniques or minimum ratios)
N/A
c. Is there a maximum floodplain depth in which development is allowed?
N/A
d. Does your jurisdiction allow below grade storage mitigation of fill in the
floodplain?
N/A
e. What is the recommended method for calculating the conveyance
compensation required, if any?
N/A
C.
Drainage Design Criteria
9.
The following questions pertain to the design criteria used in your jurisdiction.
a. When was this criteria last updated?
The drainage criteria is currently being developed for the City.
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b. If the source of drainage design criteria is not the Harris County Flood
Control District “Policy, Criteria & Procedure Manual”, City of Houston
Design Manual, Harris County Regulations or TxDOT Hydraulic Design
Manual, was a special study or analysis used to develop the criteria used in
your jurisdiction? If so, please provide a copy.
The criteria manual does contain the criteria of HCFCD and the City
of Houston, when appropriate.
10.
What is the required storm sewer design frequency in your jurisdiction?
The storm sewer systems are designed to City of Houston’s 2-year
criteria.
a. If you use a method other than rational for storm sewer design, please
describe/explain.
b. Which source of rainfall depths or Intensity-Duration-Frequency (IDF)
curves are used in this design? Please provide a copy of the curves.
11.
What is the maximum allowable storm sewer hydraulic grade line for the
design storm?
The storm sewer systems are designed to City of Houston’s 2-year
criteria.
12.
What are the tailwater requirements for storm sewer design? (e.g. top of
outfall pipe, 10- or 25-yr water surface elevation in receiving stream)
The storm sewer systems are designed to City of Houston’s 2-year
criteria.
13.
Does your jurisdiction allow open, roadside ditches for new developments? If
so, what are the requirements? (e.g. lot size or frontage)
No
14.
What is the required roadside ditch design frequency in your jurisdiction?
N/A
15.
What is the maximum allowable roadside ditch hydraulic grade line for the
design storm?
N/A
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16.
What are the tailwater requirements for roadside ditch design? (e.g. 10- or 25year water surface elevation in receiving stream)
N/A
17.
Is an extreme event sheet flow analysis required for proposed projects in your
jurisdiction? If so, what criteria is used?
City of Houston’s criteria.
18.
Are there stormwater detention criteria in your jurisdiction? If so, please
answer the following questions:
The detention rates are 0.20 acre-feet per acre for development outfalling
into a City storm sewer system having designed capacity available. For
other tracts, the rate is 0.45 acre-feet per acre. All other criteria is set to
City of Houston and HCFCD.
a. What is the minimum detention rate required?
b. For what frequency or frequencies is the detention basin outfall sized?
c. What is the maximum release rate allowed?
d. What are the freeboard requirements for detention basins?
e. Is storage volume allowed to be placed in the parking lots of a planned
development? If so, is there a maximum allowable ponding depth?
Yes. Normally, 6"
f. Are pumped detention basins allowed? If so, please answer the following
questions:
Yes
i. What is the minimum storage rate required?
City of Houston and HCFCD
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ii. How is the maximum discharge rate determined?
City of Houston and HCFCD
19.
Are any changes/improvements to the current stormwater policies, criteria or
regulations being considered? If so, please describe.
The drainage criteria is currently being developed for the City.
D.
Gage and Flood Information Data Request
20.
Has your jurisdiction ever operated any gages (recording or non-recording)
that record either rainfall data and/or flood stage data? If so, please furnish
locations, types of data, and time period of operation.
No
21.
Does your jurisdiction have information showing locations of frequently
flooded streets and the severity of the flooding (depth and frequency)? Please
furnish a copy of current and past records (maps, addresses, tables, etc.).
See attached map.
22.
Does your jurisdiction have information showing locations of flooded homes
and businesses and the severity of the flooding (depth and frequency)? Please
furnish a copy of current and past records (maps, addresses, tables, etc.).
See attached map.
23.
Does your jurisdiction have “repetitive loss” information? Please furnish a
copy of current and past records.
24.
Does your jurisdiction have a list of High-Water Marks (HWMs) that define
the maximum elevation for flood events? If so, what information was
obtained (water surface elevation, location, date, and how obtained)? Please
furnish a copy of the current and past data obtained.
No
25.
Does your jurisdiction have photos or videos of flood inundation for typical
and/or extreme storm events? Please furnish copies, preferably referenced to
specific location and date of event.
No
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