SLOAPCD RULE 431 STATIONARY INTERNAL COMBUSTION ENGINES
LAST REVISED 11/13/96

RULE 431.      STATIONARY INTERNAL COMBUSTION ENGINES (Adopted
               11/13/96)


     A.   APPLICABILITY.  This Rule applies to any stationary
          internal combustion engine rated at greater than 50
          brake horsepower and operated on any gaseous or liquid
          fuel, including but not limited to gasoline, natural
          gas, field gas, waste gas, liquefied petroleum gas
          (LPG), or diesel fuel.
    
     B.   DEFINITIONS

          1.   "Diesel Engine": A compression ignited two or
               four-stroke engine in which liquid fuel injected into
               the combustion chamber ignites when the air charge has
               been compressed to a temperature sufficiently high for
               auto-ignition.

          2.   "Emergency Standby Engine": An internal combustion
               engine used only as follows:
    
               a.   When normal power line or natural gas service
                    fails; or

               b.   For the emergency pumping of water for either fire
                    protection or flood relief.

               An emergency standby engine may not be operated to
               supplement a primary power source when the load
               capacity or rating of the primary power source has been
               either reached or exceeded.

          3.   "Lean-burn Engine": Any two or four-stroke
               spark-ignited engine that is not a rich-burn engine.

          4.   "Location": Any single site at a building, structure,
               facility, or installation.

          5.   "Maintenance Operation": The use of an emergency
               standby engine and fuel system during testing, repair
               and routine maintenance to verify its readiness for
               emergency standby use.

          6.   "Rated Brake Horsepower": The maximum brake horsepower
               rating at maximum revolutions per minute (rpm)
               specified for the engine by the manufacturer. 
               Alternately the rated brake horsepower of an engine
               shall be the maximum allowable and enforceable rating
               specified by the District, stated in the Permit to
               Operate, and accepted by the engine operator.

          7.   "Retrofit": A modification to an existing engine in
               which an aftercooler, turbocharger, or emissions
               control device has been added or the engine has been
               rebuilt to the extent that the crankshaft has been
               removed and replaced.

          8.   "Replacement": The removal of an existing engine and
               subsequent installation of a different engine in its
               place.

          9.   "Rich-burn Engine": Any four-stroke, naturally aspirated, 
                spark-ignited engine or any spark-ignited internal 
                combustion engine that is operated with an exhaust stream 
                oxygen concentration of less than four (4) percent by 
                volume before add-on controls.  For engines using a 
                catalyst, the exhaust gas oxygen content shall be 
                determined from the uncontrolled exhaust stream before the
                catalyst.

          10.  "Stationary Internal Combustion Engine": Any internal 
                combustion engine of the reciprocating type that is 
                operated at the same location for more than one year or 
                is attached to a foundation.

     C.   EXEMPTIONS.  With the exception of recordkeeping and
          reporting requirements necessary to justify an exemption,
          the provisions of this Rule shall not apply to the
          operation of stationary internal combustion engines used
          under the following conditions:
    
          1.   Engines rated at less than or equal to 50 brake
               horsepower.

          2.   Engines operated less than 200 hours per calendar year.

          3.   Emergency standby engines operated during either an
               emergency or maintenance operation.  Maintenance
               operation is limited to 100 hours per calendar year.
    
          4.   Engines used in research or teaching programs.

          5.   Engines used in agricultural operations in the growing
               of crops or the raising of fowl or animals.
    
          6.   Engine test stands used for evaluating engine performance.

          7.   Diesel engines used to power cranes and welding equipment.

     D.   REQUIREMENTS

          1.   Spark-Ignited Engines: The owner or operator of a
               spark-ignited engine to which this Rule is applicable
               shall limit emissions from that engine to no more than
               the following:

               Engine Type              NOx          CO
                                      (ppmv)        (ppmv)
                    
               Rich-burn                50          4500
               
               Lean-burn               125          4500
          
               where:    ppmv =  parts per million by volume referenced 
                                 at dry stack-gas conditions and 15 percent 
                                 by volume stack-gas oxygen (dry at 15% O2)
                         NOx  =  oxides of nitrogen (calculated as nitrogen 
                                 dioxide)
                         CO   =  carbon monoxide

    2.   In lieu of compliance with a NOx emission limit in Subsection D.1, 
         the owner or operator of a spark-ignited engine may achieve and 
         maintain a NOx reduction by volume percentage specified below: 

         Rich-burn              90 percent
         Lean-burn              80 percent

         NOx reduction by volume percentages shall be determined in 
         accordance with Subsections F.1 and F.2.  The emission limits 
         for CO listed in Subsection D.1 shall still be applicable.
    
    3.   Diesel Engines: The owner or operator of a diesel engine shall 
         limit emissions from that engine or its replacement to no more 
         than 600 ppmv NOx, or a NOx reduction by volume percentage of 
         30 percent as determined in accordance with Subsections F.1 and 
         F.2.  In addition, and CO emissions shall be limited to 4500 ppmv.  
         All ppmv values shall be referenced at dry stack-gas conditions 
         and 15 percent by volume stack-gas oxygen.

    4.   No person shall allow the discharge into the atmosphere of ammonia 
         (NH3) emissions in excess of 20 ppmv from any emission control 
         device requiring NH3 installed and operated pursuant to the
         requirements of Subsection D.1, D.2, or D.3 above.

    5.   The owner or operator of any stationary internal combustion engine 
         subject to the provisions of Section D of this Rule shall 
         demonstrate compliance with the emission limits at least once 
         every 8760 hours of engine operation or once every three (3) 
         calendar years, whichever comes first.

  E.     ENGINE OPERATOR INSPECTION PLAN.  The owner or operator of an 
         engine subject to the provisions of Subsection D.1, D.2, or D.3 
         of this Rule shall submit an Engine Operator Inspection Plan 
         (Plan) for approval by the Air Pollution Control Officer (APCO).  
         The Plan shall be updated after any change in operation.  The 
         operator may request a change to the Plan at any time.
    
         The Plan shall include the following:

         1.   The manufacturer, model number, rated horsepower, and 
              combustion type (i.e., rich-burn, lean-burn, or diesel) of 
              the engine.

         2.   A description of the NOx control system installed on the 
              engine (if any), including type (e.g., nonselective catalyst, 
              "clean-burn" combustion) and manufacturer, as well as a 
              description of any ancillary equipment related to the
              control of emissions (e.g., automatic air/fuel ratio 
              controller, fuel valves).

         3.   The facility-defined equipment identification number and the 
              location of the engine on a map or plot plan of the affected 
              facility.

         4.  A specific engine inspection procedure to ensure that the 
             engine is operated in compliance with the provisions of this 
             Rule.  The procedure shall include an inspection schedule and 
             the inspection log format as required by Section G below. 
             Inspections shall be conducted every quarter or after every 
             2,000 hours of engine operation.  In no event shall the 
             frequency of inspection be less than once per year.

         5.  A description of each preventive or corrective maintenance 
             procedure or practice that will be used to maintain the 
             engine and NOx control system in compliance with the 
             provisions of this Rule.

  F.     TEST METHODS

         1.  NOx and CO emissions, and oxygen content for compliance 
             source tests shall be determined by using ARB Method 100.

         2.  Percentage NOx reductions shall be determined by measuring 
             concurrently at the inlet and outlet of the emission control 
             device.  For engines not employing emission control devices, 
             percentage NOx reductions shall be determined by measuring 
             the uncontrolled NOx emissions prior to modification and 
             comparing with NOx emissions after engine modification.  
             A source test plan for the measurement of uncontrolled NOx 
             emissions shall be submitted to the District for approval no 
             less than 15 days prior to testing.

         3.  Source test data point intervals shall be no greater than 
             five (5) minutes and data points shall be averaged over 
             fifteen (15) consecutive minutes.

         4.  NH3 emissions shall be determined using Bay Area Air Quality 
             Management District Method ST-1B.

         5.  An alternative source test method may be used provided the 
             alternative method is at least as accurate as the test methods 
             listed above and further provided that the alternative method 
             has been approved by the ARB and EPA, and has received prior 
             written approval from the APCO.

  G.     RECORDKEEPING

         1. The operator of any engine subject to the provisions of 
            Section D of this Rule shall maintain an inspection log 
            that includes, on a monthly basis the following data:

            a.  Date and results of each engine inspection,

            b.  A summary of any preventive or corrective maintenance taken, 

            c.  The total hours of operation,

            d.  The type and quantity of fuel used, and

            e.  Any additional information required in the Engine Operator 
                Inspection Plan.
    
         2. The operator shall maintain the inspection log for a period of 
            three (3) years after the date of each entry.  The log shall 
            be available for inspection by the District upon request.

  H.     REPORTING.  On or before March 1 of each year, each owner or 
         operator with engines subject to the provisions of this Rule 
         shall submit a report to the APCO specifying the actual annual 
         fuel usage and operating hours for each affected engine.  The 
         report shall also include the engine manufacturer, model number, 
         facility-defined equipment identification number, and a summary 
         of the maintenance reports as required in Section G.

  J.     COMPLIANCE SCHEDULE

         1.   All subsections of this Rule shall apply to any new facility 
              or source obtaining an initial District Permit to Operate on 
              or after November 13, 1996.

         2.   Spark-Ignited Engines:

              a.  Any person required to modify or replace an existing, 
                  spark-ignited, stationary internal combustion engine 
                  to comply with the requirements of this Rule shall submit 
                  a complete Authority to Construct application to the 
                  APCO no later than May 1, 1999.

              b.  Any person with an existing, modified, or replacement, 
                  spark-ignited, stationary internal combustion engine 
                  shall demonstrate final compliance no later than 
                  May 1, 2000.
  
         3.   Diesel Engines: After May 1, 2000, any person with an existing 
              stationary internal combustion diesel engine to which this 
              Rule is applicable shall comply with the requirements of 
              Subsection D.3 upon retrofit or replacement of that diesel 
              engine.  A complete Authority to Construct Application shall 
              be submitted to the APCO at least 60 days prior to retrofit 
              or replacement.

         4.   The owner or operator of an engine subject to the provisions 
              of Subsection D.1, D.2, or D.3 shall submit an Engine Operator 
              Inspection Plan no later than 60 days after the applicable 
              compliance date listed in Section J.