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Ivlr. Mike Applegate, P.E. Page 3 October 24, 2003 Rule S.A.(5)(b)(X) of the Rules and Regulations requires that all new dams have a minimum of one foot of residual freeboard during the occurrence of the inflow design flood (IDF), unless a lesser freeboard standard can be considered acceptable for good clause shown. Based on information and calculations contained in the Hydrology Report, the dam will have approximately 0.4 feet of residual freeboazd during the inflow design flood. The IDF for this project is requrred to be the flood generated by the occurrence of a 100-year rainstorm event. The Hydrology Report also shows that during the IDF the water surface of the South Platte River floodplain outside of the reservoir will be at approximately the same elevation as the water surface inside of the Tigers Reservoir. Based on this information, it appeazs that the dam embankmenevent would not cause by the floodwaters of the IDF and that a failure of the dam embankment during additional flooding downstream. Therefore, the one-foot of residual freeboazd is not required for this project. $ased on this, a waiver of the aforementioned Rule is granted and the reduced residual freeboazd is considered to be acceptable for this dam project. There presently is a partially completed interconnection pipeline between the Tigers Reservoir and the Spratlen Reservoir, that is located to the north of Tigers Reservoir. The design documents for this facility were submitted to this office for our review; however, half of the structure was constructed prior to the completion of our review. This office has not accepted the design and construction of this facility, as of the date of this letter. As part of this project, an optional outlet wo~eicon~ cion of theoptional owlet wo ksdis contingent on the ' meet ibe requirements of Rule S.A.(7)(d). completion and acceptance of the aforementioned partially completed interconnection pipeline. A waiver of the construction of the optional outlet works has been requested. The requirement to construct the optioenal outl~es works is waived provided the partially completed interconnection pipeline is completed and accep Y office for use. The acceptance of the construction of the existing interconnection pipeline will be required prior to the storage of water in the reservoir above the natural ground surface. Verification of the construction of the existing interconnection pipeline will require a visual inspection of the upstream goztion of the facility by this office. If it is decided to instead construct the optional outlet works to meet the requirements of Rule S.A.(7)(d), the existing partially completed interconnection pipeline will be required to be properly abandoned by either removing the pipeline or backfill grouting the entire interior of the pipeline. This work will. also need to be completed prior to the storage of water in the reservoir above the natural g~~ 6s~ a~ •,Q¢,~~ ~ ~ ~-'t,. D R ~~ Presently, there is also an interconnection pipeline between the existing South Dahlia water storage R~ ,p facility and the Tigers Reservoir. This pipeline is constructed beneath 88`s Avenue. By letter dated June 1, 3'O~° 2000, Mr. Robert Huzjak of GEI Consultants requested a ruling on the jurisdictional status of the construction of this pipeline. At that time, we were lead to believe that the South Dahlia water storage facility and the Tigers Reservoir, then known as the North Dahlia water storage pond, were developed by excavating in~o~a urf~re. ground and water storage in these excavations would be maintained at or below the natural gr Based on our understanding of the project, a ruling was made that the pipeline was a non jurisdictional structure and the design and construction of the facility was, therefore, exemgt from our Rules and Regulations. With the construction of a jurisdictional size dam to create additional storage in the Tigers Reservoir, the interconnection pipeline is now considered.to be a jurisdicfional structure. Therefore, for final acceptance of this proposed construction project, documentation of the design and construction of this pipeline facility will be required to be submitted to this office for our review and approval. Storage of water iu the reservoir above the natural ground surface will also be contingent on our acceptance of the construction of this facility. Verification of the construction of this facility could require a visual inspection of the pipeline by this office. Parts of this facility were designed and constructed without the approval of the Staee~~nmgm~e~ez aticuaexistsEforrthe'~~ appaie7lert*f aaX;'.desr . features. This is very disconcerting. The mission of this office is public safety as it relates to the design and construction of dams in the State of Colorado. The intent of the Rules and Regulations and the State Statutes is to assure that the design and construction of dams -meet minimum standards established by the State and aze