| (a) Final approval of engineering plans and specifications for levees and other improvements for which commission approval is required; submission of final plans for exempt levees and other improvements. (1) Following approval by the commission of a proposed levee or other improvement under Texas Water Code (TWC), §16.236, the applicant shall submit final engineering plans and specifications to the executive director for approval prior to beginning construction. (2) For levees and other improvements which are exempt under TWC, §16.236, final engineering plans and specifications shall be submitted to the executive director prior to beginning construction for review to ensure compliance with preliminary plans submitted thereunder and to carry out the executive director's inspection duties under TWC, §57.117, but approval of these final plans by the executive director is not required. (3) In addition to the submission of final plans, the applicant shall also provide the executive director with proof of ownership or right to construct on the project site prior to beginning construction. Upon review and approval of the final plans of the applicant, the executive director shall notify the applicant in writing that construction may proceed. (b) Criteria for review and/or approval of final plans. Final plans of the proposed works must adequately illustrate pertinent features of the project such as planned elevations, profiles, dimensional typical cross-sections, and other features such as outlet works, drains, overflow relief structures, landfills, and roads so that an understandable project concept can be discerned. The requirements are to be considered guidelines and may be varied according to the requirements of any particular project at the discretion of the executive director. Final plans for such features as excavated channels or constructed embankments will be reviewed as to their structural integrity in accordance with the degree of hazard inherent with the project. (1) Normal requirements for final channel excavation plans are as follows. (A) Information is to be provided to indicate the type and/or classification of the soil to be excavated in the channel according to the unified soil classification system. Depth of exploratory borings shall be at least five feet below planned channel bottom grade. (B) Plans shall provide elevations and dimensions for the channel and all structures and appurtenances integral to the project such as protective linings, wingwalls, outlet works, drop inlets, aprons and riprap. (C) Unlined channels must be constructed to a nonerosive grade. All channels should be accessible for maintenance or repair. (D) All concrete placement shall be reviewed for intended use. (E) Use or disposal of excavated material shall be clearly shown on final plans. (F) All specifications to be followed by the contractor shall be included with plans submitted. (G) The applicant must have an acceptable operation and maintenance program and budget. (2) Normal requirements for final levee or dike construction plans are as follows. (A) For purposes of review, final plans of dikes and levees will be classified into one or a combination of the following: (i) the dike that holds back water at all times: (I) with landfill; (II) without landfill: (-a-) high-risk protection (dwelling or high value land); (-b-) low-risk protection (agricultural); (ii) the levee that holds back water only during floods: (I) with landfill; (II) without landfill: (-a-) high-risk protection (dwelling or high value land); (-b-) low-risk protection (agricultural). (B) Normal requirements are as follows. (i) Foundation and borrow source information obtained from exploration will indicate the type and/or classification of the soil according to the unified soil classification system. The borings should be at least to a depth equal to the height of the embankment. In some cases, additional depth of borings may be required. The natural groundwater table elevation shall be given if water is encountered in the borings. The soils to be used shall be relatively impervious and consist of clay and clayey material. At least 15% of the material must pass the #200 sieve and the plasticity index of the material must be above 15. Fill material shall have no stones over six inches in diameter and no organic material (roots, etc.). (ii) Elevations and dimensions of all proposed structures (levees, dikes, conduits, etc.) including those to be used for drainage shall be noted. (iii) Lengths and distances between the various components of the system, i.e., lengths of conduits and pipes; distances between dike or levee and natural stream, and borrow area or ditches, shall be noted. (iv) Compactive effort proposed to be used in project specifications shall be noted. The compactive effort required may vary with the type of dike or levee. The compaction of the material may be obtained by any means that is suitable. The soil shall be compacted to a minimum density of 95% using the standard proctor compaction test at approximately 3.0% optimum moisture content. Fill shall be placed in lifts of not more than 12 inches thick and properly processed, if needed, prior to compaction. Methods to be employed to obtain compaction shall be contained in specifications for the project. (v) Sides of levees that are to remain exposed shall be adequately protected. Plans shall provide for establishing a protective grass cover or for an alternate treatment where climate will not support a vegetative cover. (vi) All pipes and conduits passing through the dike shall have anti-seep collars to increase the percolation path by a minimum of 15%. The immediate area below drainage outfalls shall be protected by riprap or concrete. (vii) All concrete placements shall be reviewed for intended use. (viii) The foundation area shall be stripped. Stripping shall include removal of all grass, trees, and surface root systems for the full width of the levee. (ix) Provision shall be made for an embankment key. Methods employed to control subsurface seepage shall be reviewed in accordance with soil conditions present and with the degree of hazard inherent in the project. (x) Materials removed by stripping or from the key way shall be used only on the dry side of the finished levee. (xi) All specifications to be followed by the contractor shall be included with the plans submitted. (xii) The applicant shall formulate and carry out an acceptable operation and maintenance program and budget. |
