Abbreviated Drainage Plan
A brief written plan stating and schematically showing how a small proposed land development project will satisfy stormwater management requirements of these Guidelines. Generally this is applicable only to projects that will be devoid of detention facilities and public stormwater infrastructure of any kind. This may be accomplished with a site plan showing vertical dimensional controls or a site grading plan.
Land area(s) adjoining or near a proposed land development project that contributes stormwater runoff to, or through, the project at the time of hydrologic analysis or in the future. Above-project areas are included in the drainage study area.
Full potential urbanization of a basin or watershed area in compliance with the Comprehensive Plan. Such an area may include one or more subdivisions, one or multiple property holdings, wholly undeveloped land or both developed and undeveloped land areas.
The Bryan District Office of the Texas Department of Transportation (TxDOT) operates several Area Offices, each of which has responsibility for several counties. The engineer in charge of each Area Office has the title of Area Engineer.
For uniformity of meaning within these Guidelines land areas are defined according to the general hierarchy listed below. Specific definitions of each are included in the Glossary.
Drainage Study Area
Design Drainage Area
The flood having a one percent chance of being equaled or exceeded in any given year, also known as “100 year” flood.
A land area making up a portion of a watershed. A basin can be thought of as the entire area contributing storm flow to a watercourse serving as a tributary to a principal named stream. Several basins usually comprise a watershed.
B-CS Technical Specifications
All items pertinent to design or construction of stormwater facilities of any kind included in the latest adopted version of the Bryan-College Station Unified Techncial Specifications and Standard Details. See “Technical Specifications”
Full completion of any land development project in all of its phases, if any, representing the entire contiguously owned tract(s), whether proposed for near-term or possible future development. This refers to: completion of any single-lot site project; the final completion of any multi-stage project entailing a site project staged over time; or final completion of multiple subdivision projects collectively making up a parent tract (or preliminary plat submittal) representing ownership of an un-platted parcel of land regardless of size.
BFE – Base Flood Elevation
The high water surface elevation(s) along a watercourse resulting from the base flood passing down that watercourse.
CFS A measure of water flow in cubic feet per second
City Either the City of Bryan or the City of College Station as applicable
The official city engineer of Bryan or College Station as applicable
The cities of Bryan and College Station collectively, or each individually.
Conditional Letter of Map Revision as related to FEMA requirements for managing FEMA-designated flood prone areas
The urban general plan officially adopted by the City
An identifiable route by which concentrated (non-sheet flow) stormwater will travel within and from a project area to a discharge point at a main channel of the Primary Drainage System
The principal person in Brazos County government who has responsibility for engineering decisions.
Conveyance Pathway Area
See “Pathway Area”
Datum Any level surface to which elevations are referred (for example, mean sea level); is also referred to as datum plane, although it is not actually a plane
Design Drainage Area
The surface area contributing stormwater runoff to any particular point of design in a stormwater management system of any kind. Examples can range in size from the area contributing to a single curb inlet, to that contributing to a flood control facility astride a major stream. Depending on the point of design, the design drainage area can equal an entire watershed, an entire basin, a drainage study area, an off-project area, a project area or portion(s) of any of these areas.
Temporary storage and metered release of stormwater
A permanent facility designed for the temporary storage and metered release of stormwater without creating a permanent pool of water.
Stormwater out flow from an area of any kind, or from a storm water feature such as a conduit or a detention facility.
Drainage Development Permit
A permit issued by the City that allows the start of clearing, grubbing, or earthwork as the early stage(s) of a land development project, based on an approved drainage plan or an approved abbreviated drainage plan.
An interest in land granted to the City for the maintenance of a drainage facility, on which certain uses are prohibited; and providing for the entry and operation of machinery and vehicles for maintenance purposes.
All elements (public and private) necessary to manage and convey stormwater runoff from its initial contact with earth to its disposition in a watercourse making up the primary drainage system of the Bryan-College Station area. These may include but are not limited to storm sewers, improved channels, unimproved drainage ways, areas within drainage easements or drainage right of way providing concentrated or overland sheet flow, and all appurtenances to the foregoing, such as inlets, manholes, junction boxes, headwalls, culverts, etc.
A detailed representation of how stormwater will be managed as part of a proposed land development project (site or subdivision). Usually accompanied by (or incorporated into) an engineering report, it is to be based on an approved preliminary drainage plan
A report, prepared by a Registered Professional Engineer, that presents the drainage plan for a land development project (site or subdivision) in compliance with the provisions of these Guidelines. It must document the hydrologic and hydraulic analyses accomplished to address the project area, above-project area(s) and pathway area(s), and any watercourse conveying stormwater to or from the project area.
See “Drainage Report”.
Drainage Study Area
The full extent of land area that must be analyzed for the effects of stomrwater runoff, whether part of a project, upland of the project, or contributing stormwater runoff to the conveyance pathway downstream of the project. The drainage study area is equal in size to the sum of the project area, the above-project area, if any, and the pathway area, if any.
Drainage Right Of Way
An area of land dedicated to the City for the purposes of conveying and containing stormwater flow, constructing drainage facilities, and/or allowing entry and/or operation of equipment for maintaining such drainage features and facilities.
The vertical distance from a datum, usually the NGVD, to a point or object. For example, if the elevation of point “A” is 802.46 feet, point “A” is 802.46 feet above some datum.
Existing or proposed buildings, foundations, drainage structures, streets (including bridges and culverts), utilities, or earthwork of any kind which is situated in floodplain, or flood fringe areas, the geographic limits of which are defined on the official Flood Insurance Rate Maps of the City.
Equitable encroachment into floodplain or flood fringe areas along a significant reach of both sides of a watercourse, as a function of “low side” and “high side” hydrologically proportionate areas.
A Registered Professional Engineer duly authorized and licensed, under provisions of the Texas Engineering Practice Act, to practice the profession of engineering.
The process whereby the surface of the earth is loosened and carried away by the action of wind, water, gravity, ice, or a combination thereof.
The hydrologic condition of the project area or the drainage study area that exists (or existed) prior to any proposed land development work and at the time for which a hydrologic analysis is conducted. Where man-made topographic features predate adoption of these Guidelines, such features shall be considered “exiting condition”.
Extraterrritorial Jurisdiction (ETJ)
Within the terms of the Texas Municipal Annexation Act, means the unincorporated area, not a part of any other city, which is contiguous to the Corporate Limits of the City, the outer boundaries of which are measured from the extremities of the corporate limits of the City outward for such distances as may be stipulated in the Texas Municipal Annexation Act, in which area, within the terms of the act, the City may enjoin the violation of its subdivision control ordinance.
FEMA Federal Emergency Management Agency of the US Government
F.H.A. Federal Housing Administration, an agency of the US Government.
Flood Insurance Map
See “Flood Insurance Rate Map”
Flood Insurance Rate Map
Any of a series of maps published by FEMA that depicts the geographic limits of flood prone areas along the principle watercourses of the Cities, for the purpose of identifying those areas in which property owners are eligible to participate in the National Flood Insurance Program.
Overbank areas along a watercourse that are subject to inundation by stormflow due to unusually larger storms events.
The official study, or collection of studies, that defines the flood plains, flood fringe, and floodways of the primary drainage system and tributaries thereof as required in connection with the National Flood Insurance Program sponsored by FEMA.
The channel and adjacent overbank areas of a river or other watercourse that may not be filled or hydraulically altered if such fill or alterations will cause a cumulatively increase in the base flood elevation of more than one foot.
That portion of a channel bank, detention embankment, or other stormwater management facility that is above the water surface elevation expected to be generated by the design storm for which the facility is designed.
The design guidelines referenced in this document: “Bryan and College Station Uniform Stormwater Design Guidelines”
A branch of science that deals with practical applications (such as the transmission of energy or the efforts of flow) of liquid (such as water) in motion
A science dealing with the properties, distribution, and circulation of water on the surface of the land, in the soil and underlying rocks, and in the atmosphere
Land Development Project
Any proposed site development or subdivision project requiring building permit(s) or platting under provisions of City ordinances.
A parcel of land having been divided from a parent tract via a plat duly processed and approved by the City, and filed of record in county records under the platting provisions of Texas State Law.
LOMA Letter of Map Amendment as related to FEMA requirements for managing FEMA-designated flood prone areas
Letter of Map Revision as related to FEMA requirements for managing FEMA-designated flood prone areas
The lowest floor, or the lowest enclosed area (including basement), of a structure. An unfinished or flood resistant enclosure, usable solely for the parking of vehicles, building access or storage, in an area other than a basement area, is not considered a building’s lowest floor, provided that such enclosure is not built so as to render the structure in violation of the applicable non-elevation design requirements of City ordinances.
Master Drainage Plan
An official plan of the City for comprehensive management of stormwater runoff in an entire basin or watershed, or in specific reaches thereof.
Mean Sea Level (MSL)
The average height of the surface of the sea for all stages of the tide taken over a 19-year period.
Named Regulatory Watercourse
The major watercourses or streams in the Bryan-College Station region having been ascribed with names and listed in Table B-1, Appendix B.
The cover and topography of land before any man-made changes that would substantively affect the path or intensity of stormwater runoff.
A stream, waterway, or channel more or less in the alignment created by natural forces, with our without man-made alteration of its surfacing and configuration at limited locations.
Land area(s) that drain to the conveyance pathway of a project, but that are not included in the project area or above-project area(s). See conveyance pathway area.
Principal Named Streams (Watercourses)
See “Named Regulatory Watercourses”
Preliminary Drainage Plan
See “Preliminary Drainage Report”
Preliminary Drainage Report
A report showing a schematic representation of how stormwater will be managed as part of a proposed land development project. It will document pertinent topographic, hydrologic, and land ownership characteristics of all land areas contributing stormflow to a project area, as well as all hydrologic parameters proposed for analysis of design stormflow throughout the project.
The entire land area of a proposed site development or subdivision project, at buildout condition, into which buildings, structures, and/or street and utility facilities are to be constructed. This area(s), together with any above-project area(s) and pathway area(s) make up the drainage study area that must be considered in developing plans for stormwater management facilities for the project.
See “Project Area”
Reach A length or portion of a watercourse, whether wholly natural or influenced by man-made improvements or alterations.
A flood control facility approved by the City as a mechanism for managing stormwater runoff form a large land area comprised of one or more subdivisions, one or multiple property holdings, developed and undeveloped land areas, or any combination of such areas.
See “Named Regulatory Watercourses”
The total land area that contributes stormwater runoff to a named regulatory watercourse in the Bryan-College Station region. Each such watercourse has a watershed area that is made up of basins. The sum of the land area(s) in a watershed’s basins equals the land area of the watershed.
A facility that provides for the storage of stormwater flows by means of a permanent pool of water or a permanent pool in conjunction with a temporary storage component.
Right of Way
Land set aside for street and storm drain facilities or utilities, or exclusively for stormwater management purposes.
A term referring to a category of land use zoning. See Urban Estates.
An area of land divided by platting into lots none of which are smaller than one (1) acre, and which is served by roadways having a rural cross section (one characterized by presence of roadside ditches and no curb and gutter). See also Urban Estates.
Deposits of detached soil particles or rock fragments after being transported from their site or origin by runoff water.
Site See “Site Project”.
A land area consisting of a single platted lot or two or more contiguous platted lots upon which a building project is planned, consisting of building structures, parking, and other facilities and exclusive of public streets. A site project may or may not include public utilities situated in easements, or stormwater management facilities situated in drainage right of way. See “Site”
Any stormwater management facility or technique the design of which is not specifically addressed by these Guidelines or the B-CS Technical Specifications.
Standard Specifications for Construction
See Technical Specifications
Stormwater Planning Conference
A meeting between property owners/developers (including their representatives) and the City Engineer (or his/her designee) for the purpose of identifying how these Guidelines and the provisions of stormwater management ordinances relate to land area(s) proposed for near-term or future development.
A walled and roofed building that is principally above the ground, as well as a manufactured home.
Associated with a drainage study for a drainage report, this is the geographic limits of the hydrologic and hydraulic analyses that are required for the study.
A land development project involving the division of land into lots and ROW for public streets and utilities or the dividing of land into individual lots for near term construction or planned long term construction of site projects.
A Registered Public Surveyor or Registered Land Surveyor as licensed by the State of Texas.
Swale A shallow drainage way characterized as having a “V” shape the sides of which have very flat slopes, generally on the order of sides 6 horizontal to 1 vertical (6:1) or flatter.
TAMU Texas A&M University
TAMUS The Texas A&M University System
Technical Design Summary
A drainage report format that may be used in lieu of a traditional prose report. Following a question/answer process, it is to use the forms provided in Appendix D, with attachments as needed.
See “B-S Technical Specifications”
Waterways, watercourses, streams, or creeks that directly flow into the Named Regulatory Watercourses of the Bryan and College Station region. Some may be referred to by a name on maps or other reference.
TxDOT Texas Department of Transportation.
This term generally relates to the extent to which impervious materials and plant growth will, at some future time, cover land contributing stormwater runoff to one or more design points in a stormwater management system. Of necessity this requires some plan or a series of assumptions about future characteristics of undeveloped areas. See Anticipated Development
A class of zoning resulting in single family homes on relatively large lots, generally one acre or larger. See Rural Subdivision.
Any depression, channel, storm sewer, or culvert serving to give direction to a current of stormwater.
See “Regulatory Watershed”
Glossary of Community Development Services – Download [Optimized PDF]
Glossary of Community Development Services – Download