1 Scope
This code specifies the principles and criteria that shall be followedwhen using ash and slag damming technique to design dam bodies inwet-type ash storage yards of coal-fired power plants.
This code is applicable not only to the design of ash dams ofvalley ash yards that employ hydraulic ash handling technique, butalso to the design of ash embankments in ash yards on the beaches ofrivers, lakes and sea (hereinafter referred to as beach ash yard) andash yards on plains. It is not applicable to the design of dry-type ashstorage yards.
The provisions specified herein for ash dams are also applicableto ash embankments,unless specifically prescribed otherwise
3. Terms and Definitions
The following terms and definitions apply to this code.
3.0.1
Ash dam
Hydraulic structure used to store ash and retain water in valleyash yard.
3.0.2
Ash embankment
Hydraulic (marine) structure used to store ash and retain water inplain and bcach ash yards.
3.0.3
Dam body
Entire ash dam consisting of a primary dam, subdams anddeposited ash and slag.
3.0.4
Primary damInitial dam body when ash dam bcing constructed by stages.
3.0.5
Subdam
Dam body heightened on top of deposited ash on dam frontwhen ash dam being constructed by stages.
3.0.6
Ash and slag
Mixture of pulverized coal ash collected by precipitators andslag discharged from bottom of boilers in a coal-fired power plants.
3.0.7
Ash and slag damming
A by-stage damming technique to gradually heighten dam bodiesby building subdams on deposited ash on dam front with earth-rockmaterial or ash-slag material in ash yard.
3.0.8
Ash and slag filling-siltation dammingAsh and slag damming by hydraulic filling.
3.0.9
Terminal dam height
Maximum possible dam hcight dctermined by taking intoaccount natural topography and geological conditions of ash storagcyard, requirements by power plants and other factors.
3.0.10
Aggregate capacity
Total volume of ash, slag and flood that can be accommodatedby ash yard with terminal dam height.
3.0.11
Length of dry bank
Horizontal distance from the point where water surface crossesash surface to the point where ash surface crosses upstream slope ofdam on the cross-section perpendicular to dam axis
3.0.12
Limited length of dry bank
The length of dry bank that can be maintained to restrict heightof phreatic line and ensure safety of dam body during operation.
3.0.13
Ash storage elevation
Elevation where surface of ash deposited in ash storage yard
4-Basic Design Provisions
4.1General Provisions
4.1.1 The environmental protection of ash storage yards shall meetthe following requirements:
I The ash storage yards shall be provided with safe and stabledam bodies that comply with relevant design standards to prevent ashslag and ash water from flowing away.
2 The ash storage yards shall be equipped with reliable drainagesystems, with drainage structures being located at a distance sufficient toclarify ash water and able to recycle the clarified ash water.
3 During the operation of ash storage yards, the limited length ofdry bank shall be maintained to ensure the safety of dam bodies, whilethe ash surface of dry bank shall be wetted, when necessary, by divertingash water thereto or sprinkling water to prevent dust pollution.
4 The ash storage yards shall be covered with soil and reclaimedpromptly once they are filled up.
5 Where an impermeable layer is necessary at the bottom ofash storage yard as required by environmental impact report, it can beconstructed of rolled clay or geomembrane. Vertical anti-seepagemeasures can be taken where geological conditions are permissible.6 The pollution control criteria of ash storage yards shall complywith GB18599.
4.1.2 Ash and slag damming shall meet the following requirements:l The dam bodies shall meet the requirements of design codein terms of stability.
