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2. Types of Transfer Stations

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					                                     Lecture No. 10

                                Transfer and Transport
                                    Chapter 10, p.325

                                      Waste
                                      Generation


                                Waste handling, separation,
                                storage and processing
                                at the source



                                       Collection


               Transfer and                                   Separation and processing
               Transport                                      and transformation of
                                                              solid waste


                                       Disposal




1. Need for Transfer Operations

A. General

   Used when:
- Direct hauling to the processing center or disposal site is no long economically feasible.
- When the disposal site or processing center is in a remote location and cannot be
    reached directly by highway.
 Integral part of MRFs.
 Becoming popular AT landfills for individuals and other non-commercial haulers.


B. Excessive Haul Distances

   Originally horse drawn smaller carts transferred their waste to larger vehicles.
   The internal combustion engine and cheap fuel fostered direct haul to dumps.
   Considering NIMBY and the economy of scale of larger sites, the current trend is to
    mega-facilities in remote locations once again necessitating transfer stations.
   Decision between transfer and direct haul is usually an economic one.

**Problem 10-2, p.357
                 Lecture No. 10, Transfer and Transport, Page No. 2


2. Types of Transfer Stations (Fig.10-1, p.329)

   Three types: direct-load, storage-load, combined direct-load and discharge load.

A. Direct-Load Transfer System

    The wastes in the collection vehicles are emptied directly into:
- the vehicle that will transport the wastes to the final disposal side
- into facilities to compact the wastes into transport vehicles or
- into waste bales.
 Surge - volume of waste that can be stored temporarily on the loading platform
 Large capacity - Direct from collection to transport vehicle typically employing a two
     level operation. Compaction and moving the waste within the transfer vehicle is using
     done by some kind of back hoe with clamshell tip stationed on the top ramp. An
     alternative is to direct load into a compactor which in turn moves the waste directly
     into the haul trailer.
 Medium and small capacity - Generally small with less equipment and concrete to the
     point where Demsey Dumsters are placed on a patch of ground. Alternately, a dual
     level system can be made by raising the dumpers or lowering the dumsters, such that
     the waste is thrown down into the containers. Individuals seem to like this system.
 Example
**Problem 10-5, p.358

B. Storage-Load Transfer System
 Wastes are dumped into a pit or unloading area as opposed to the transfer vehicle. The
   pit is typically a larger area and thus facilitates unloading of collection vehicles and
   shortens waiting time. Auxiliary equipment such as payloaders move the material
   from the storage area into the transfer vehicle. The storage time is typically 1-3 days.
 Large capacity - (Fig. 10-12,13, p.338) San Francisco model. A large pit at a lower
   level is surrounded by unloading collection vehicles. Two bull dozers break up the
   wastes and push the wastes into hoppers which discharge into the transfer vehicles.

C. Combined Direct-Load and Discharge Load Transfer Stations.
 Usually a multipurpose facility: perhaps a transfer station and a MRF.

3. Transport Means and Methods
A. Motor Vehicle Transport (T10-1,2, p.346)

    Used where roads are available and include:
- trailers
- semi-trailers
- compactors
 Vehicles should satisfy the following requirements:
- minimum cost
                   Lecture No. 10, Transfer and Transport, Page No. 3

- wastes must be covered during haul operations
- must be designed for highway travel
- do not exceed allowable weight limits
- unloading must be simple and dependable
 Open top semi-trailers are popular. A recent innovation is the drop-bottom trailer in
    which the bottom of the center portion of the trailer is lowered which yields additional
    capacity without increasing the length.
 Maximum volume, axle weight, number of vehicles and outside dimensions are a
    consequence of state regulations.
 Unloading methods:
- self-emptying (Fig. 10-19, p.347)
    - hydraulic dump beds
    - powered internal diaphragms, most common
    - moving floors,
- auxiliary equipment
    - pull-off type - wastes are pulled out of the truck by either a movable bulkhead or
    wire cables placed forward (nearer the cab) of the truck.
    - hydraulically operated tipping ramps.
- The advantage of self-emptying units is the speed because no additional equipment or
    workers are required. The advantages of auxiliary units is lower capital costs and the
    relatively simple and dependable methods used.
 Example
       Given: Pahrump, Nevada, pop. 18,300, has decided to transfer its wastes via truck tractor-
       semitrailer combinations using no compaction and monoque construction. Loading, a round-trip
       and unloading to the disposal area takes 3.6 hours.
       Find: They want to know how many units they will have to buy.

       T6-3, p.138 3.82 lb/cap.day, Note that only residential and commercial have been included. The
       disposition of the other categories is a matter of discussion which must be resolved before capital
       facilities are committed to.
       T10-2, p.347 46,000lbs/truckload
       1. Tonnage
       Tonnage = 18,000 cap x 3.82 lb/cap.day x 7 days/week
       Tonnage = 481,320 lbs/week



       2. Truck Capacity
       Weekly truck capacity = 46,000 lbs/truck x 40hours/week x 1trip/3.6hours
       Weekly truck capacity = 511,111lbs/truck.week

       3. Number of trucks
                              481320 lbs/week
       Number of trucks =
                            511111lbs/truck.week
       Number of trucks = .94 trucks
       It would be probably be more reliable to use a larger fleet of smaller trucks. This method would
       not only provide backup in case of breakdown, accident, etc. but would allow once truck to be
       loaded while the other(s) were on the road.
                  Lecture No. 10, Transfer and Transport, Page No. 4


B. Rail Transport

    Seattle to Columbia Ridge model. A distance of 300 miles in which 25-28 tons are
     compacted into a 40' shipping container.
 Probably the wave of the future for LA.
 Interesting modifications possible:
- Special fork lifts to load the containers.
- rail cars also equipped with set down tires which will allow road transport.

C. Water Transport

   Barges, scows and special boats have been around a long time.
   Ocean disposal is no longer legally practiced.
   Can not be moved during high seas.

D. Pneumatic, Hydraulic etc.

   Largest pneumatic system at Disney World in Florida. May be suitable for high
    density areas feeding a central collection point. Complex control valves and isolation
    equipment. Difficult to imagine a half eaten ice cream bar being moved along. Easy
    to imagine health and odor problems.
   Hydraulic system - Macerate the waste and pipe it to a remote location. Potential for
    great economies except scarcity of water in LA. Ocean water? Must the transport
    water be treated?

4. Transfer Station Design Requirements

   Type - The key element is will the waste be merely taken from one truck to another or
    will waste recovery operations such as recycling, composting, diversion be
    incorporated into the design.
   Capacity - Waiting time for unloading vehicles vs. capital costs of a larger facilities.
   Equipment - rubber tired or tracked to push the waste around, scales.


5. Location of Transfer Stations

   Near as possible to the center of the service area.
   Near highways, close access avoid houses.
   Minimum public environmental objections
   Economical construction and operation.

  Example
**Problem 10-13, p.359
                Lecture No. 10, Transfer and Transport, Page No. 5

EXAMPLES
10-2, 10-5, 10-13

HOMEWORK
Read Chapter 10, Transfer and Transport, pp. 325-360
Problems, p. 357, 10-1, 10-4, 10-6, 10-12
                              Lecture No. 10, Transfer and Transport, Page No. 6



LECTURE NO. 10 ........................................................................................................................................ 1

TRANSFER AND TRANSPORT................................................................................................................ 1

1. NEED FOR TRANSFER OPERATIONS .............................................................................................. 1
    A. GENERAL ............................................................................................................................................... 1
    B. EXCESSIVE HAUL DISTANCES ................................................................................................................ 1
2. TYPES OF TRANSFER STATIONS (FIG.10-1, P.329) ....................................................................... 2
    A. DIRECT-LOAD TRANSFER SYSTEM ......................................................................................................... 2
    B. STORAGE-LOAD TRANSFER SYSTEM ...................................................................................................... 2
    C. COMBINED DIRECT-LOAD AND DISCHARGE LOAD TRANSFER STATIONS. .............................................. 2
3. TRANSPORT MEANS AND METHODS ............................................................................................. 2
    A. MOTOR VEHICLE TRANSPORT (T10-1,2, P.346) ..................................................................................... 2
    B. RAIL TRANSPORT ................................................................................................................................... 4
    C. WATER TRANSPORT ............................................................................................................................... 4
    D. PNEUMATIC, HYDRAULIC ETC. ............................................................................................................... 4
4. TRANSFER STATION DESIGN REQUIREMENTS .......................................................................... 4

5. LOCATION OF TRANSFER STATIONS............................................................................................. 4

				
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