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CSULA Senior Design Technical Memo _ 1.docx

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					CSULA Senior Design Project
Preliminary Design Report




                    2011 Senior Design Project Team
       College of Engineering, Computer Science and Technology
                    Department of Civil Engineering
                                01/27/2011


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                                                              Table of Contents
1.     INTRODUCTION ............................................................................................................................................ 2
2.     EXISTING DESIGN .......................................................................................................................................... 2
3.     TEMPORARY SOLUTION ............................................................................................................................... 2
4.     DESIGN OPTIONS .......................................................................................................................................... 3
     4.1.     EXISTING MODIFIED STRUCTURE DESIGN ............................................................................................................ 3
     4.2.     OPEN CHANNEL DESIGN ...................................................................................................................................4
     4.3.     CANTILEVERED PIPE DESIGN.............................................................................................................................. 5
     4.4.     BURIED PIPE DESIGN ....................................................................................................................................... 6
     4.5.     BRIDGE DECK DESIGN...................................................................................................................................... 8
     4.6.     JETTY DESIGN................................................................................................................................................. 9
     4.7.     RESERVOIR WITH UNDERGROUND PIPELINE DESIGN ........................................................................................... 10
5.     COST ESTIMATION...................................................................................................................................... 12
6.     CONCLUSION .............................................................................................................................................. 12
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1. INTRODUCTION
       The Los Alamitos Bay pumping station is necessary for the removal of storm water.
  This particular pump station is located in the southwest shoreline of Los Alamitos Bay in
  Long Beach, CA. The pump station houses three main water pumps and two sump
  pumps; capable of transporting water at a combined rate of 182 cubic feet per second.
  The water comes into the pump station through rainwater storm drains on lines A and B
  on the drawings. This water is then passed through a filter which takes out all the large
  pieces of trash that are in the water. It is then stored in an underground tank till it is
  ready to be pumped out into the bay.

2. EXISTING DESIGN
  The existing discharge design of the pump station consists of three reinforced concrete
  pipes. The first pipe is 36 inches in diameter and 84 feet in length and the two other
  pipes are 30 inches in diameter and 84 feet in length. All three pipes are currently
  supported by a timber pier with eight piles. The pier is found to have rotated several
  degrees due to a broken pile which has allowed the pipes to also settle a few inches.
  The third pump is on a low level use operation to avoid any complications that may arise
  due to the failed support, however during high levels of rain were influent flow is at a
  maximum, the pump must be fully operated to prevent potential flood conditions. Geo-
  technical, environmental, structural, and hydraulic studies need to be reassessed for
  future improvements. Considering the aesthetics, the discharge lines functionality, and
  the quality of water impact, proposed designs aim to be environmental friendly and cost
  effective.

  Can you say anything about why the pier failed? Proposing a repair without having some
  idea of why something failed is not prudent.

3. TEMPORARY SOLUTION
       Due to the failure of the structure an intermediate remediation was implemented
  until a permanent solution can be acquired. Figure 1 displays the failure of the timber
  supports and the temporary solution implemented for this issue. This called for a jack to
  hold the structure to insert Crib wall Headers at the areas of failure. When the support
  was finished, the jack was lowered and removed. However, it is not aesthetically pleasing
  and most importantly unsafe. Due to this cause of structural failure, safety measures
  have been implemented at the pump house facility.
                                                                                  Page |3




                      Figure 1 : Concrete slab supporting damaged structure



4. DESIGN OPTIONS

4.1. Existing Modified Structure Design

        This option would consider renovating the existing structure with new materials;
    therefore it would require complete replacement. This renovation would make use of
    concrete encasings for the timber piles. Acknowledging the aesthetics of the pier, this
    renovation would call for fewer piles producing a more aesthetically pleasing site. To
    accomplish this task, a variety of materials for different components of the pier can be
    used; such materials would include concrete, steel, and fiberglass.




                      Figure 2 : Pipes imbedded in concrete deck with railings
                                                                                    Page |4


                           Design Option : Existing Modified Design
                             Pros                           Cons

                       no permit required            not aesthetically pleasing


                   quick construction timeline     life expectancy of 25-50 years

                                                   deeper piles needed if fewer
                   lifeguard shack can be kept
                                                       piles are to be used
                                                    heavy equipment would be
                                                      needed for this option



4.2. Open Channel Design

         An open channel design is an effective- feasible design considering the amount of
    time and money that is needed. The design simply transports the water being pushed by
    the pumps into a free flow open channel. Once the water reaches the channel, water
    would then flow to the bay under the force of gravity, following the path of the
    incorporated concrete header. Further measures would be taken to avoid erosion at the
    end of the open channel. The design would require removing the existing structure
    along with the pipes to incorporate a downward bend at the outlet of the pipes (see
    Figure 4). The channel design would consist of a concrete header that can be precast
    off-site and brought in for on-site assembly and placed on top of the beach grounds.
    The actual forming and pouring would be done at the beach. However, during
    construction of the open channel it would require a temporary cofferdam to create a
    dry working environment.




                                  Figure 3 : Open channel design
                                                                                   Page |5


                                  Design Option : Open Channel
                                Pros                        Cons
                                                   not aesthetically pleasing if
                     easy to repair / maintain
                                                       only concrete is use
                                                 dangerous, might cause injury
                      fast construction with
                                                  if safety measures are not in
                         pre-casted parts
                                                              place
                                                  permit will be hard to obtain
                     can handle a lot of water
                                                 due to the usage of concrete in
                   discharge from pump station
                                                         the environment
                                                 beach space would be taken up
                         long service life
                                                  by the open channel structure
                       pumps don’t have to
                          work as hard



4.3. Cantilevered Pipe Design

        Another solution to solve the current problem is a cantilevered pipeline that would
    have a span of eighty feet from the outflow pipe elbow. The pipe would be split into
    two pipe segments each measuring 42 feet in length. There would be two concrete
    supports supporting the pipeline; one located at the start of the pipeline, and the other
    at the segment connection (as seen in Figure 6). To support the pipe, it would be
    extended upward forty-two feet from the ground surface. This upward support will act
    as a column and cable-stayed cables would connect the top of column to the
    cantilevered pipeline. Similar to a cable-stayed bridge design, the cables would prevent
    the pipeline from collapsing or deflecting during storm water discharge.
                                                                                      Page |6




                              Figure 4 : Cantilevered Pipeline with Deck


                                 Design Option : Cantilevered Pipe
                                Pros                          Cons
                    freestanding / few supports
                                                     high quality materials needed
                              needed

                    minimal materials required          water surface clearance

                     withstand seismic activity,
                                                     difficult to repair if damaged
                     wind load and gravity load

                       aesthetically pleasing


                             cost ( # 4 )




4.4. Buried Pipe Design

         Due to damages to the existing structure, the proposed solution can improve
    dramatically the aesthetics of the beach site where the structure is located. We propose
    the complete removal of the existing structure and the replacement of the existing
    drainage pipes starting from the transition elbow to the end of the pipe. The new
    design proposes a trench starting from the transition elbow to the end of the existing
    pipe. The new drainage pipes will be placed underground; the trench will be covered
    with concrete that will serve as a foundation for the pipes and to prevent pipe flotation.
    The end of the pipe will have a 45 degree elbow with a pipe extending to the surface of
    the water. The tip of the pipe will have a screened flap gate mechanism that will open
                                                                                      Page |7


    and close automatically as water flows through it. Figure 5 displays a visual illustration
    of the potential pipe design. In order to construct this design the installation of a
    cofferdam is required to keep a dry working area.




                              Figure 5 : Underground pipeline design


Some of the sub-options that can be included in this design include the following:

   1. Pipe outlets can be encased in a decorative statue such as a whale or a ship. This
      hides the pipes making them only visible while discharging water. This also protects
      the pipes from potential impacts from boats or any other watercrafts. This option
      offers protection and is the most aesthetically pleasing.
   2. Pipe outlets can be surrounded by a floating dock. This dock will be hollow to
      accommodate the pipes and will be lined inside and out with rubber to protect the
      pipes from any impacts. The floating dock will be anchored to the seabed with cables
      or chains to allow for tidal movement. This option offers less protection and is not as
      aesthetically pleasing as sub-option 1, but has a lower profile, making it less visible.
      However, the pipe outlets will be visible.
   3. Pipe outlets are surrounded by a rigid dock. This dock is the same as sub-option 2,
      except it is anchored to the seabed with piles and will not move with the tide. This
      option offers slightly more protection than sub-option 2, but will be more visible
      during low tide, and pipe outlets will still be visible.
                                                                                     Page |8


                                  Design Option : Buried Pipe
                               Pros                         Cons
                                                   large excavation to place new
                    Aesthetics improvement
                                                   pipes and concrete foundation
                                                      due to buried pipeline the
                                                     access incase of damage or
                          easy to maintain
                                                    need for replacement will cost
                                                              ineffective
                                                     methods used to inspect the
                   pipes out of sight from the
                                                        underground pipe are
                       surrounding area
                                                              expensive
                                                   requirement of cofferdam to
                      automatic flap gate          create dry environment during
                                                   construction



4.5. Bridge Deck Design

        This alternative consists of building a pre-fabricated concrete deck in segments,
    transporting each segment to the site, and installing them onto supports. These
    supports could either be built on-site or manufactured elsewhere. The deck would
    remain above water level and the pipes would remain at the same elevation as the
    current structure.




                           Figure 6 : Bridge Deck with imbedded pipelines
                                                                                            Page |9


                                    Design Option : Bridge Deck
                                 Pros                         Cons
                    be easier to modify according        further changing the design
                        to design preference               may prove to be difficult
                    aesthetically pleasing, neighbor   pre-cast off site then bringing it
                                friendly                 on site will be troublesome
                    fabricating the segments of the
                                                        access to pipe will be difficult
                        deck off site will reduce
                                                             after construction
                                 impacts
                      no need to hide pipes from
                                 view
                        can protect pipes from
                              corrosion
                       opportunity to use other
                       materials to manufacture
                               the pipes



4.6. Jetty Design

         A Weir Jetty is defined as "a pier projecting out into the waterway”. Usually the
    usage of a jetty is to slow down beach erosion by influencing the tide, or to help protect
    the harbor, therefore, the jetty must also take into consideration any natural
    phenomena (i.e. tidal movements). In this case, instead of protecting a harbor it would
    protect the pipes as they will be concealed within it and it would appear like a typical
    jetty as shown in Figure 7 The pipes will be placed on top of boulders and covered by
    smaller rocks to protect the pipes from any damage.




                              Figure 7 Image of jetty at Hillsboro Inlet, FL.
                                                                                      P a g e | 10


                                       Design Option : Jetty
                               Pros                             Cons
                                                      silting and sedimentation
                        impact protection
                                                               transport
                                                   must provide adequate lighting
                     ease of construction and       to help prevent collisions of
                           maintenance              ships due to extension onto
                                                                bay
                     typical near ocean front
                                                        corrosion will occur
                            properties
                                                        liability issue due to
                       aesthetically pleasing
                                                      pedestrians walking on it
                                                    Will affect /disturb long shore
                  simple construction techniques    transport of sand along bay.
                     using different materials          Bay cause unintended
                                                            consequences
                   no need to be concerned with
                      hiding pipes from view


4.7. Reservoir with Underground Pipeline Design

         Another design option to discharge the rainwater into the bay is to implement a
    reservoir system. For this option, a partially-buried reservoir would be placed on the
    beach right after the pipes from the sump reach and turn on to the beach area. As the
    pumps are activated the water would begin to fill the reservoir. The reservoir would be
    built with multiple buried pipes on the bottom which would extend across the beach
    and resurface at the bottom of the bay (As seen in Figure 8). At this point all the water
    in the reservoir would be discharged into the bay using gravity flow. The reservoir
    would be built to an optimal size so water does not overflow. Multiple discharge pipes
    must be utilized for this reason, so that discharge from the reservoir is at equilibrium
    pressure to the water which is pumped into the reservoir. If for any reason the pumped
    water does exceed discharge rate, the reservoir will be designed in a way to spill over
    towards the beach, similar to a dam. This may be caused by unusually high tides or
    heavy rain.
                                                                   P a g e | 11




         Figure 8 : Reservoir w. underground pipeline


 Design Option : Reservoir with Underground Pipelines
         Pros                          Cons
boats and swimmers will have
                                     difficult to construct
full access to the beach water
                                   permits will be difficult to
maintenance will be minimal
                                            obtain
                                  safety precautions will be
structure failures eliminated    taken into consideration for
                                         the reservoir
concrete reservoir would be      failure of this structure would
   resistant to ocean life          cause a beach shutdown

       long service life
                                                                                     P a g e | 12


5. Cost Estimation

   This is

                                                       Cost Ranking
                               Design Option
                                                    ( higher to lower )
                              existing modified              1
                                open channel                6
                               buried pipeline              3
                               cantilever pipe              5
                                 bridge deck                7
                                    jetty                   2
                             reservoir with pipes           4




6. Conclusion

      After considering several design alternatives in this document, our emphasis of
  choosing a final design will lie on the design options of the cantilever pipe, buried pipe,
  open channel, and existing renovation. The design team will further research these
  options and will be presented in the future preliminary design report.

				
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