1、 ASCE STANDARD ANSI/ASCE/EWRI 44-13 American Society of Civil Engineers Standard Practice for the Design and Operation of Supercooled Fog Dispersal Projects This document uses both the International System of Units (SI) and customary units. Published by the American Society of Civil Engineers Standa
2、rd Practice for the Design and Operation of Supercooled Fog Dispersal Projects iiiSTANDARDS ASCE 28-00 Standard Practice for Direct Design of Precast Con-crete Box Sections for Jacking in Trenchless Construction ASCE/SEI/SFPE 29-05 Standard Calculation Methods for Struc-tural Fire Protection SEI/ASC
3、E 30-00 Guideline for Condition Assessment of the Building Envelope SEI/ASCE 31-03 Seismic Evaluation of Existing Buildings SEI/ASCE 32-01 Design and Construction of Frost-Protected Shallow Foundations EWRI/ASCE 33-09 Comprehensive Transboundary Interna-tional Water Quality Management Agreement EWRI
4、/ASCE 34-01 Standard Guidelines for Artifi cial Recharge of Ground Water EWRI/ASCE 35-01 Guidelines for Quality Assurance of Installed Fine-Pore Aeration Equipment CI/ASCE 36-01 Standard Construction Guidelines for Microtunneling SEI/ASCE 37-02 Design Loads on Structures during Construction CI/ASCE
5、38-02 Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data EWRI/ASCE 39-03 Standard Practice for the Design and Opera-tion of Hail Suppression Projects ASCE/EWRI 40-03 Regulated Riparian Model Water Code ASCE/SEI 41-06 Seismic Rehabilitation of Existing Buildings A
6、SCE/EWRI 42-04 Standard Practice for the Design and Opera-tion of Precipitation Enhancement Projects ASCE/SEI 43-05 Seismic Design Criteria for Structures, Systems, and Components in Nuclear Facilities ASCE/EWRI 44-05 Standard Practice for the Design and Opera-tion of Supercooled Fog Dispersal Proje
7、cts ASCE/EWRI 45-05 Standard Guidelines for the Design of Urban Stormwater Systems ASCE/EWRI 46-05 Standard Guidelines for the Installation of Urban Stormwater Systems ASCE/EWRI 47-05 Standard Guidelines for the Operation and Maintenance of Urban Stormwater Systems ASCE/SEI 48-11 Design of Steel Tra
8、nsmission Pole Structures ASCE/SEI 49-12 Wind Tunnel Testing for Buildings and Other Structures ASCE/EWRI 50-08 Standard Guideline for Fitting Saturated Hydraulic Conductivity Using Probability Density Functions ASCE/EWRI 51-08 Standard Guideline for Calculating the Effective Saturated Hydraulic Con
9、ductivity ASCE/SEI 52-10 Design of Fiberglass-Reinforced Plastic (FRP) Stacks ASCE/G-I 53-10 Compaction Grouting Consensus Guide ASCE/EWRI 54-10 Standard Guideline for Geostatistical Esti-mation and Block-Averaging of Homogeneous and Isotropic Saturated Hydraulic Conductivity ASCE/SEI 55-10 Tensile
10、Membrane Structures ANSI/ASCE/EWRI 56-10 Guidelines for the Physical Security of Water Utilities ANSI/ASCE/EWRI 57-10 Guidelines for the Physical Security of Wastewater/Stormwater Utilities ASCE/T the content in the remaining ASCE/EWRI 44-05 sections was unchanged. The supplement was prepared and de
11、veloped through the ASCE con-sensus standards process, the remainder was undertaken by the AWM SC, then the fi nal consensus for the Revision of ASCE/EWRI 44 was conducted before trying to obtain acceptance by ANSI. ASCE/EWRI 44-13 has been prepared in accordance with the ASCE Standards Writing Manu
12、al, August 20, 2010, revision with recognized engineering principles and should not be used without the user s competent knowledge of the underlying prin-ciples for a given application. The American Society of Civil Engineers (ASCE) recognizes the work of the Atmospheric Water Management Standards C
13、ommittee of the Environmental and Water Resources Institute (EWRI). The primary authors of this standard were the EWRI Atmospheric Water Management Standards Committee s Fog Dispersal Ad Hoc Subcommittee members: Thomas P. DeFelice (chair), Conrad G. Keyes, Jr., Darin Langerud, and Maurice Roos. We
14、also acknowledge the many who contributed their comments, reviews, illustrations, and photographs. Thomas P. DeFelice, PhD, ASCE Mem, WMA CO, PMP, Maryland The Board of Direction approved revisions to the ASCE Rules for Standards Committees to govern the writing and maintenance of standards develope
15、d by ASCE. All such standards are devel-oped by a consensus standards process managed by the ASCE Codes and Standards Committee. The consensus process includes balloting by a balanced standards committee and reviewing during a public comment period. All standards are updated or reaffi rmed by the sa
16、me process every fi ve years if at all possible. Requests for formal interpretations shall be processed in accor-dance with Section 7 of ASCE Rules for Standards Committees, which are available at www.asce.org . Errata, addenda, supple-ments, and interpretations, if any, for this standard can also b
17、e found at www.asce.org . This standard has been prepared in accordance with recog-nized engineering principles and should not be used without the user s competent knowledge for a given application. The publi-cation of this standard by ASCE is not intended to warrant that the information contained t
18、herein is suitable for any general or specifi c use, and ASCE takes no position respecting the validity of patent rights. Users are advised that the determination of patent rights or risk of infringement is entirely their own responsibility. This standard, ASCE/EWRI 44-13, is a combination of ASCE/E
19、WRI 44-05 and its supplement. The supplement covered This page intentionally left blank Standard Practice for the Design and Operation of Supercooled Fog Dispersal Projects viiCONTENTSFOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
20、 . . . . v1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Historical Review of Supercooled Fog Dispersal Operations . . . . . . . . . . . . . . . . . . . . . . . . 11.2 The Status of Supercooled Fog Dispersal Tech
21、nology . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.0 Fog Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.1 Fog Droplet Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、. . . . . 52.2 Fog Characteristics as Applied to Fog Dispersal Operations . . . . . . . . . . . . . . . . . . . . . . . . . 72.3 Seeding Strategy for Dispersing Supercooled Fog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73.0 The Design of Supercooled Fog Dispersal Projects. . . . .
23、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.1 Project Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.2 Delivery Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93.3
24、Seeding Agent Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113.4 Targeting and Delivery Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123.5 Experience and Training. . . . . . . . . . . . . . . . . . . . . .
25、. . . . . . . . . . . . . . . . . . . . . . 133.6 Seeding Suspension Criteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133.7 Legal, Environmental, and Social Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134.0 Supercooled Fog Dis
26、persal Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.1 Operations Manual. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.2 Personnel Requirements . . . . . . . . . . . . . . . . . . . . . . . . . .
27、. . . . . . . . . . . . . . . . . . 154.3 Operational Decision Making . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164.4 Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164.5 Public Relations, Informa
28、tion, Involvement, and Safety Considerations. . . . . . . . . . . . . . . . . . . 165.0 Evaluation of Supercooled Fog Dispersal Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196.0 Glossary of Acronyms and Terms . . . . . . . . . . . . . . . . . . . . . . . . . . .
29、. . . . . . . . . . . . . . . . . . 217.0 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258.0 Conversion Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27I
30、NDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29This page intentionally left blank Standard Practice for the Design and Operation of Supercooled Fog Dispersal Projects 1CHAPTER 1.0 INTRODUCTION populations. Fog cleari
31、ng in open-pit mines can allow the safe resumption of mining operations that were suspended due to decreased visibility (ASCE/EWRI 2005 ). Ice fogs are a special case and are slower to dissipate than supercooled fogs because they are composed mostly of tiny ice crystals and they generally form at ai
32、r temperatures below about 243 K ( 30 C) (e.g., Huffman and Ohtake 1971 ). Ice fog dis-persal is fundamentally different from the dispersal of super-cooled fogs and may be more appropriately labeled ice fog suppression . Ice crystals predominate and form by heteroge-neous nucleation and, in some ins
33、tances, by homogeneous nucle-ation . Ice fogs are primarily caused by unnatural sources of water vapor, which may include automobile and aircraft exhaust, exhaust from utility plants, and open water, such as cooling ponds (ASCE/EWRI 2005 ). Benson (1969) indicated that decreasing the ambient tempera
34、ture of these moisture sources did improve visibility. Most attempts to disperse ice fogs have included electric fi elds, dehydrators of various types (e.g., gas, furnace, automobile), air movement by helicopters, polyethylene rafts, plastic fi lms (e.g., polyethylene), injection wells, cooling towe
35、rs, and chemical fi lms (e.g., hexadeconal, ethylene glycol monobutyl ether). Presently, the standard technique used to sup-press ice fog caused by exposed water sources employs a thin ethylene glycol monobutyl ether fi lm. This fi lm is harmless to marine life (it is biodegradable) and lasts much l
36、onger than other fi lms, but it is less effective in suppressing ice fog than hexadeconal fi lm (ASCE/EWRI 2005 ). McFadden (1976) and McFadden and Collins (1978) provide details of these tech-niques. Ice fog suppression techniques will not be discussed in this document. The focus of this standard i
37、s on the dispersal of supercooled fog. 1.1 HISTORICAL REVIEW OF SUPERCOOLED FOG DISPERSAL OPERATIONS Supercooled fog is colloidally stable but is otherwise in a ther-modynamically metastable state (e.g., Silverman and Weinstein 1974 ). Thus, supercooled fog can be dissipated by growth and sedimentat
38、ion of ice crystals. Seeding supercooled fog with ice-forming particles ( nuclei ) may yield visibility improvements of at least 1.6 km (1 mi) within 15 min following seeding (Fig. 1-1 ). The results are so repeatable that randomized statistical verifi ca-tion is generally considered unnecessary. As
39、 a result, super-cooled fog dispersal has been operational since 1950 in the United States and since 1952 in Russia. The most frequent loca-tions of these operations are at airports. Suitable seeding tech-niques are primarily dependent upon wind, temperature, and the supercooled liquid water amount.
40、 Some involve the introduction of artifi cial ice nuclei into the air from either ground-based or airborne delivery systems. Other techniques employ liquid carbon dioxide, nitrogen, or propane to disperse fogs. Liquid Fogs can pose a signifi cant threat to public safety and quality of life in the ai
41、r, on land, and at sea. For example, the luxury liner Andrea Doria collided with the Stockholm in fog off New York and sank on its 1956 maiden voyage. Fifty-one people died and millions of dollars in property were lost (Silverman and Weinstein 1974 ). An airliner (Flight VD8387) overran the runway i
42、n heavy fog after landing in Yichun, in northeastern China, killing 43 passengers on August 24, 2010. Extended periods of fog can have large economic impacts on the avia-tion, tourism, transportation, and mining industries (ASCE/EWRI 2005 ). For example, in the early 1970s one fog at one U.S. airpor
43、t caused an estimated $100,000 loss of revenue due to aircraft diversions, delays, and cancellations (Silverman and Weinstein 1974 ). The total annual weather impact on U.S. avia-tion is an estimated $3 billion for accident damage and injuries, delays, and unexpected operating costs, and weather is
44、a primary contributing factor in 23% of all aviation accidents (Kulsea 2002 ). Although extended foggy periods can have negative impacts on agriculture and the mental health of the general public, there are some situations in which fog is benefi cial, such as where fog water is collected for drinkin
45、g water in arid regions (e.g., Sche-menauer 1998 ), and where fog supplies some of the necessary moisture to vegetation. For example, fog supplies needed mois-ture to the northern California redwood trees during the summer dry season (e.g., Schemenauer 1998 ). Another example is the notorious winter
46、 fog in the San Joaquin Valley of California, which provides an important portion of the winter dormancy requirements of many deciduous orchard crops in the region. The San Joaquin valley fogs are also known as “tule” fogs and are in the category of “warm fogs” that are not normally super-cooled, as
47、 their temperatures are often just above freezing (ASCE/EWRI 2005 ). The harmful effects on transportation alone have been suffi -cient justifi cation for attempts to modify or disperse fogs. Sil-verman and Weinstein (1974) note that fog was the subject of the fi rst scientifi cally designed weather
48、 modifi cation effort of any kind. This may partially explain why supercooled fog dis-persal is perhaps the only weather-modifi cation technology that does not require long experimentation and careful mea-surement to detect results, because results are both visible and nearly instantaneous. The most
49、 frequently cited goal of any supercooled fog dispersal project is to increase visibility. An increase in the local temperature can be a by-product of the clearing activities. Fog dispersal operations reduce the threat to public safety by increasing the visibility over highways and airport runways. Dispersing fog to increase visibility, espe-cially at airports, has tremendous economic valueparticu-larly at the local levelas transportation returns to normal levels. Addit
