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WESTECH ENGIlVEF.RING, INC. ~_ CONSULTING ENGINEERS & PLANNERS Mr. Leonard Lodder, AIA Arbuckle Costic Architects, Inc. 363 State Street Salem, OR 97301-3533 January 5, 1999 RE: Streetscape Public Storm Drain Improvements Courthouse Square - Salem, Oregon J.O. 1969.100.0 Dear Leonard: ~RB~C ~L~ ~~ST~~ /qN _ 6199 ~RECE~ 9 VF,~ As you know, the number of connections to the Streetscape public storm drain system increased signi~cantly from the design development documents to the ~inal contract drawings. The invert elevations of the building storm drain services required the public storm drain main to be increased from 15-inches to 18-inches because there was less grade available. Due to the public storm drain size increasing above 15-inches, it is possible that the City of Salem could require additional storm drain improvements for the project since, the cunent downstream pipe is only 15-inches. , The cunent public storm drain design requires a new 18-inch piping system draining to the intersection of Chemeketa Street and Church Street where it connects to an existing public 15-inch storm drain. Based on previous discussions with the City during the preliminary design, the existing 15-inch storm drain system would operate under pressure during the 10 year storm event. However, the preliminary design was for a new 15-inch storm drain connecting to the existing 15-inch storm drain system at the intersection of Church Street and Chemeketa Street. Since the final design required increasing the line to 18-inches, the City may require replacement of the existing 15-inch storm drain with a new 18-inch pipe from the cunent point of connection (Churc~ Street and Chemeketa Street), down Church Street to the intersection of Church Street and Center Street. We recommend budgeting additional money for surveying, engineering and construction costs to remove the existing 15-inch storm drain system and replace it with a new 18-inch storm drain. This is approximately 3001inear feet as estimated based on the attached City of Sa1em storm drain as-built information. We do not feel design of this system is justi~ied at this time, since the City of Salem Public Works Department must decide whether any additional storm drain improveme~ts will be required or not. We estimate that you should budget approximately $30,000 for this additional work should the City require the additional improvements discussed above. Also, the design development budget should be increased to cover the cost for the increased pipe size and other final design changes due to ~ coordination with other consultants and the City's preliminary comments. 3841 Fairview Ind~strial Dr. S.E., Suite 100, Salem, Oregon 97302 Phone: (503) 585-2474 Fax: (503) 585-3986