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r I RIIIYN_ AND ASSOCIATES INC. EHGlHEEllS - PLANI/EllS - SURVEYORS Robayna and Associates, Inc, City of Sunny Isles Beach RFQ No. 11-11-02 r 1 r 1 I }> French drains cannot be located where there are contaminated soils. .. Exfiltration pipe should be ] 5 inches minimum, with larger diameters required depending on the type of roadway. .. The invert elevation for exfiltration pipe should be at or above the design water table for Biscayne Bay and is dependent on tidal cycles when working in costal areas. .. Miami-Dade County Department of Permitting, Environment and Regulatory Affairs (PERA) suggests a design water table of 1.60 feet NGVD. }> The depth of the French drain trench will be determined from the geotechnical report borings. }> Sumps must be provided at inlets to minimize entrance of oils and sediments into exfiltration system. Baffles should be provided at signalized intersections or adjacent to parking. }> In-situ soil exfiltration capacity is typically determined by the SFWMD "Usual Open-hole Test," or FDOT percolation test method. These tests will provide values for the hydraulic conductivity of the soil. , I I 1 ! ,; I . I J I i 1 I. I Drainage Wells: In areas where space is inadequate to provide exfiltration trench or alternate treatment methods, drainage wells are utilitized. Either fed through gravity or force main. The injection wells are permitted by FDEP and Miami-Dade County PERA as Class V wells and rules set forth in Rule 62- 528 of the Florida Administrative Code (FAC). There is a rule of thumb which dictates the average of one well for every acre of contributing area. At present it appears that two well will be needed. r I }> Drainage wells have a requirement for the treatment of runoff defined by the receiving aquifer. }> In the South Florida Costal area a 90 second detention time is required prior to discharge through a well. The detention tank must be separated from the well with a baffle to reduce the potential for oil, grease and other floating material to reach the well. .. The drainage well is limited in that at a maximum it can only receive the 5-year I-hour rain event of approximately 3.2 inches per hour. .. The regulatory agency enforces the use of a large head-loss of approximately 1. 5' which can make a system seem infeasible in locations with very ground low elevations. }> The drainage well capacity can be complimented by the installation of French drain r , -f '-.-t . J ill. Geotechnical Investi!mtion and Evaluations u.s. South Engineering & Testing Lab., Inc. has performed numerous geotechnical site investigations in the entire State of Florida. These investigations are performed following the guidelines as set forth by ASTM. The experienced professionals provide an insight to the clients regarding the type of structures the soil can hold and necessary modifications to increase the strength of the existing sub-grade materials. All work is performed in accordance with the ACI and ASTM standards. They have a fully equipped laboratory for material testing. The staff has extensive experience in providing these services. They serve a vast range of clients from a small residential building compaction testing and concrete pours to the compaction tests of roadways and large concrete pours for multi-unit structures. IV. Landscape Presel'Vation It is expected that some landscaping modification may be needed along the roadway and in the least Miami-Dade County PERA has been requiring that all necessary steps be taken to preserve all trees within 20 feet of a work area. 57