SANITARY SEWAGE SYSTEM RECOVERY ASSESSMENT

File: 011696_129_15_021.txt
Page: 021
Total Pages: 71







                  II. WASTEWATER COLLECTION AND CONVEYANCE SYSTEH


                       1.   General Description.      The wastewater   conveyance
                  system consists of gravity lines        connecting   individual
                  buildings to gravity sewage mains, screw pump lift stations    I
                  and centrifugal pump stations and force mains to transport the
                  sewage over distances.    Some of the pump stations pump to
                  other pump stations and others pump directly to one of the
                  sewage treatment plants. There are 17 major pump stations and
                  56 secondary pump stations with approximately 160 kilometers
                  'of force main. The gravity systeml which consists mainly of
                  200 mm and 250 mm pipe, totals over 41700 kilometers in length
                  and has approximately 110,000 manholes with vented '-covers.
                  The. are 14 6 odor c 'ontrol stations consisting of chemical
                  addition, activated carbon air filters, air injection-, and
                  sealing throughout the system. The system of gravity lines
                  and pump stations is based on several drainage basins within
                  the city.   The flow is carried from within these drainage
                  areas to the three Wastewater treatment plants serving the-
                  City. A significant portion (approximately. 89%) of the piping
                  used throughout the system is asbestos-cement pipe. The major
                  pump stations have been designed and built over the past 25
                  years. The oldest station, A5. was constructed in.1966 and
                  the- newest station was constructed in 1986. Several hav;e been'
                  rehabilitated as late as 1986.       Most of the major pump
                  stations have odor control facilities installed. All of the
avity by-
                  pass and most were designed with an auxiliary generator for
                  operation during power outages. it seems unnecessary to note
                  that we are dealing with a major system having many components
                  which are critical to proper operation.      See Figure 5 for
                  diagram -of the collection system,, and Figure 6 for a flow
                  diagram of a typical major pump station.


                      2.     Pre-invasion condition.'      The collection and
                  conveyance system has been plagued with problems for many
                  years. Odor control was a pre-invasicin high priority item.
                  Several studies have been made concerning the general
                  condition of the -system and- presenting recommendations for
                  corrective actions. The most notable is the Master Plannim
                  Study by Black & Veatch completed in 1989. It presents an in-
                  depth analysis of the system and the major problem areas which
                  existed prior to the invasion such as:

                            Unsewered areas in the city center

                            Raw sewage-discharges from the Ardiya wastewater
                            treatment plant
                            Odor problems kithin the collection system and at

                                                                                 21.
Box ID = BX000000
Unit = CONST ENG LABS  
Parent Organization = CORPS OF ENGS   
Folder Title = SANITARY SEWAGE SYSTEM RECOVERY ASSESSMENT                                                      
Subject = SANITARY SEWAGE SYSTEM RECOVERY ASSESSMENT
Document Number =        129
Image file name = 00000022.tif