Exhibit 10.17
                        AMENDMENT TO RETENTION AGREEMENT

         Pursuant  to this  Amendment,  effective  July 9, 1999,  the  Retention
Agreement between Arthur C. Riese (you) and Harding Lawson Associates Group Inc.
is amended as follows:

         It is agreed that the Corporate Reorganization on or about June 1, 1999
is deemed to  constitute  an event that is or would  constitute  Good  Reason as
defined in Paragraph 19(k).  The time within which you may terminate  employment
for the June 1,  1999 Good  Reason  and  trigger  Severance  Benefits  under the
Agreement is hereby  extended to December 31, 1999. All other  provisions of the
Agreement remain in full force and effect.



Date     July 29, 1999                      /s/ Robert Costello
                                            Robert Costello
                                            President - Chief Executive Officer



Date     July 30, 1999                      /s/ Arthur C. Riese
                                            Arthur C. Riese