1、UFC 3-210-10 15 NOVEMBER 2010 UNIFIED FACILITIES CRITERIA (UFC) LOW IMPACT DEVELOPMENT APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-UFC 3-210-10 15 NOVEMBER 2010 Any copyrighted material included
2、 in this UFC is identified at its point of use. Use of the copyrighted material apart from this UFC must have the permission of the copyright holder. U.S. ARMY CORPS OF ENGINEERS NAVAL FACILITIES ENGINEERING COMMAND (Preparing Activity) AIR FORCE CIVIL ENGINEER SUPPORT AGENCY Record of Changes (chan
3、ges are indicated by 1 . /1/) Change No. Date Location This UFC supersedes UFC 3-210-10, dated 25 October 2004, UFC 3-210-10N (DRAFT) and ITG FY10-2, both dated 6 April 2010.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-UFC 3-210-10 15 NOVEMBER 201
4、0 FOREWORD The Unified Facilities Criteria (UFC) system is prescribed by MIL-STD 3007 and provides planning, design, construction, sustainment, restoration, and modernization criteria, and applies to the Military Departments, the Defense Agencies, and the DoD Field Activities in accordance with USD(
5、AT geographical location, site requirements, available sites, programmed space requirements related to increased impervious area, and the ability of the installation to maintain the LID-IMP. These set points will also help to determine the proper resource allocations to apply for the implementation
6、of the LID site. LID is a method of SWM that focuses on the macro vision for site development. LID is implemented on every square foot of the site at the point of rainfall onward. LID-IMPs used in conjunction with conventional SWM will create a treatment train to hold, infiltrate, and filter the sto
7、rmwater runoff. The LID site will contain less channelization of stormwater, less impervious pavement, more trees, more open ditches (less curb and gutter), and more planting buffers (rainwater filters). Many parameters must be weighted in the design of a LID site. Design must match the particular r
8、egional conditions. Many of these site conditions affect the design of LID. Regional differences in weather patterns, soil types, groundwater conditions, existing development status, and current stormwater patterns will greatly influence the actual design and layout of the LID site and the choice of
9、 the LID-IMPs. However, one of the most important parameters will be the ratio of increased impervious surface area to the available land area or change in land cover. Optimal LID implementation on a suitable site may result is a reduction in project cost. Classic LID design should reduce the amount
10、 of disturbed land, reduce impervious surface area, eliminate curb and gutter, reduce the size of pipes and holding ponds, increase the area planted in low maintenance tree cover, and reduce high maintenance structural planting beds and Provided by IHSNot for ResaleNo reproduction or networking perm
11、itted without license from IHS-,-,-UFC 3-210-10 15 NOVEMBER 2010 18 grass. Building a large facility on a small site will cost more to implement LID than building a small building on a large site. The small site will require the selection of IMPs that are structural in nature and are more expensive
12、to build and maintain, while the small building on the large site can use the more organic LID-IMPs that are less costly and more easily maintained. 2-3 EPA LID GUIDANCE The following EPA manuals are referenced as sources: “Reducing Stormwater Costs through Low Impact Development (LID) Strategies an
13、d Practices” and “Low Impact Development (LID) A Literature Review”. These manuals were based on the PDGR document “Low-Impact Development Design Strategies; An Integrated Design Approach”, and is geared toward general site development. Sites on military bases may have additional constraints that wi
14、ll influence which LID-IMPs may be used. Other Federal Directives and Executive Orders that affect LID planning and design must be identified and considered. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-UFC 3-210-10 15 NOVEMBER 2010 19 APPENDIX B:
15、 CHAPTER 3 - STORMWATER MANAGEMENT Human development increases impervious surfaces. Buildings, roads, sidewalks, and parking lots quickly shed rainwater and increase the percentage of rainfall that ends up as runoff. The resulting increase in runoff volume and the peak flows create negative conseque
16、nces such as stream degradation and flooding risk. The principal objective of LID is to retain this increase in runoff on-site. LID techniques allow the developed site to mimic the pre-development hydrologic conditions. LID builds on the conventional SWM philosophies and carries them a step further.
17、 LID processes begin at the point where the rain falls. Considering incorporating LID concepts, tools, and approaches requires assessment of the following at a minimum: Will the concept closely mimic the hydrology of pre-development condition thereby meeting certain regulatory requirement and/or res
18、ource protection goals? Will the concept mitigate adverse effects from increased stormwater runoff from the project? Can the drainage conveyance structures be optimized and reduce the overall cost of the project? What might be the hurdles for public acceptance? If required for the project to move fo
19、rward, can these be reasonably achieved? Implementing LID alone on the project may not suffice in meeting all regulatory requirements. LID must be used in combination with applicable BMPs in order to continue to produce effective SWM benefits. 3-1 HYDROLOGIC CYCLE Dr. David Maidment in his Handbook
20、of Hydrology states: “The hydrologic cycle is the most fundamental principle of hydrology. Water evaporates from the oceans and the land surface, is carried over earth in atmospheric circulation as water vapor, precipitates again as rain or snow, is intercepted by trees and vegetation, provides runo
21、ff on the land surface, infiltrates into soils, recharges groundwater, discharges into streams, and ultimately, flows out into the oceans from which it will eventually evaporate once again. This immense water engine, fueled by solar energy, driven by gravity, proceeds endlessly in the presence or ab
22、sence of human activity.” Of the total precipitation that occurs, a portion of it is lost through the following: (i) interception due to land cover (ii) evapotranspiration (iii) surface depression storage (iv) infiltration Only the excess precipitation results in runoff that reaches receiving water
23、bodies, such as streams and lakes. The process of infiltration is responsible for the largest portion of rainfall losses in pervious areas. LID techniques seek to mimic pre-development hydrologic condition in the post-development phase. An understanding of the dynamics and inter-relationships in the
24、 hydrologic cycle is essential in preserving the pre-development hydrology. A comparison of pre-development and post-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-UFC 3-210-10 15 NOVEMBER 2010 20 development hydrologic conditions is evaluated for f
25、our basic measures runoff volume, peak rate of runoff, flow frequency/duration, and water quality. These four evaluation measures are discussed below: Runoff Volume: LID techniques, if implemented properly into site design, will result in no net increase in runoff for a specified design storm event.
26、 Peak Rate of Runoff: LID is designed to maintain pre-development hydrologic conditions for all storms smaller than the design storm event. If additional controls are required, either to meet the state or local regulations and/or flooding issues for unusual storm events, conventional SWM facilities
27、may be designed and implemented. Flow Frequency/Duration: LID techniques mimic pre-development hydrologic conditions if implemented properly. The flow frequency/duration should be almost the same. Water Quality: Because of the very nature of decentralized hydrologic source control, the nonpoint sour
28、ce pollution is greatly reduced, thereby, increasing the water quality of the receiving water bodies. Table 2 compares and summarizes concepts of stormwater management and LID techniques. For designs with LID-IMPs, it is appropriate to analyze the site as discrete units and rationalize on a case-by-
29、case basis. When calculating the runoff potential from LID sites one should consider land cover, impervious areas, its connection with centralized collection system, soil type and texture, and antecedent moisture condition. These should all be considered on a site-specific basis. 3-2 STORMWATER DISP
30、OSAL VS. STORMWATER MANAGEMENT The main principle of incorporating LID elements into site planning design is to ensure that there is no net increase in runoff volume for the design storm. As detailed in Chapter 2 of this manual, there are a number of techniques that can be employed in eliminating th
31、e increase. The main processes or practices that affect elimination of an increase in runoff volume for the design storm include infiltration at decentralized locations, increasing the length and time of flow over pervious areas, and disconnecting impervious areas that drain to stormwater collection
32、 systems. These help to retain the increase in runoff from new development on-site. Conventional SWM facilities are primarily designed to divert unusual storm event runoff volumes and to control flooding and downstream impacts due to this increased runoff, but also provide water quality benefits. Pr
33、ovided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-UFC 3-210-10 15 NOVEMBER 2010 21 Table 2: Summary of Concepts of SWM and LID Techniques. Concepts of SWM Concepts of LID Techniques End-of-pipe stormwater treatment. Stormwater is treated at or very close
34、 to the source/origination of runoff. Centralized collection system Decentralized system Reroute stormwater away from the site quickly and efficiently Mimics the pre-development hydrologic condition. The goal of LID is to retain the same amount of rainfall within the development site as that was ret
35、ained on the site prior to the project Many of the stormwater management facilities are designed to control or attenuate peak runoff LID techniques reduce the size of stormwater management facilities. SWM facilities are designed to treat first-flush i.e. first inch of runoff from impervious areas of
36、 development. LID techniques may suffice to treat the first-flush on-site without a need for separate treatment options. Table 2 above contrasts conventional SWM methods that use “end-of-pipe” treatment and LID techniques that may reduce land requirements associated with conventional treatment and m
37、ay make the overall design more aesthetically pleasing if incorporated early on during the planning and design phase. LID may reduce the overall costs of a project and reap benefits in protecting the environment and natural habitats. Table 3 summarizes how conventional SWM and LID technology alter t
38、he hydrologic regime for on-site and off-site conditions. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-UFC 3-210-10 15 NOVEMBER 2010 22 Table 3: Comparison of Conventional SWM and LID Technologies Hydrologic Parameter Conventional SWM LID On-Site
39、Impervious Cover Encouraged to achieve effective drainage Minimized to reduce impacts Vegetation/Natural Cover Reduced to improve efficient site drainage Maximized to maintain pre-development hydrology Time of concentration (Tc) Shortened, reduced as a by-product of drainage efficiency Maximized and
40、 increased to approximate pre-development conditions Runoff Volume Large increases in runoff volume not controlled Controlled to pre-development conditions Peak Discharge Controlled to pre-development design storm (2 year maximumbasedon permissible velocities.Usuallynota limitation,buta designconsid
41、eration.Nota factorUsuallynota limitation,buta designconsideration.Mustlocate down gradientofbuilding foundations.WaterTable/Bedrock2-to4-ftclearanceabove watertable/bedrockrecommended2-to4-ftclearanceabove watertable/bedrockrecommendedGenerallynota constraint.Generallynota constraint.Generallynota
42、constraint.2-to4-ftclearancerequiredProximityto building foundationsMinimumdistance of10 ftdown gradientfrombuildingsand foundationsrecommendedMinimumdistance of10 ftdown gradientfrombuildingsand foundationsrecommendedMinimumdistance of10 ftdown gradientfrombuildingsand foundationsrecommendedMinimum
43、distance of10 ftdown gradientfrombuildingsand foundationsrecommendedNota factorMinimumdistance of10 ftdown gradientfrombuildingsandfoundationsrecommendedMax.depth2-to4-ft depthdepending on soiltype6-to10-ft depthdepending on soiltypeNotapplicableNotapplicableNotapplicable6-to10-ft depthdepending on
44、soiltypeMaintenanceLowrequirement,propertyownercan include in normalsite landscape maintenanceLowrequirementLowrequirement,routine landscape maintenanceLowrequirement,routine landscape maintenanceLowrequirementModerate to highSource: Low-Impact Development Design Strategies, prepared by Prince Georges County, Maryland Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
