§ 105.89. Letters of Amendment and Letters of Authorization for modification of dams and reservoirs.
(a) Projects which do not modify top of dam elevation, normal pool elevation, or normal operation of the pool level may be authorized by Letter of Amendment when the dam has an existing permit or by Letter of Authorization when the dam meets § 105.12(b) (relating to waiver of permit requirements). The permittee or owner shall provide the following information:
(1) Reports and data detailing the conduct and results of investigations and tests necessary to determine the safety, adequacy and suitability of design, including:
(i) Data concerning subsoil and rock foundation conditions.
(ii) Data concerning exploratory pits, drilling, coring and tests to determine seepage rates.
(iii) Data concerning the strength tests necessary to measure the physical properties and behavior of foundations and embankment materials at the dam or reservoir site.
(iv) Data concerning the geology of the dam site or reservoir area, indicating possible hazards such as faults, weak seams and joints.
(v) Data concerning availability and quality of construction materials.
(vi) A ‘‘Dam Stability Report’’ as required under § 105.97 (relating to stability of structures).
(vii) Other information as may be necessary to determine the safety, adequacy and suitability of the design, including the design calculations for the dam, which shall be made available to the Department on request.
(2) In addition to the site plan and cross sectional views required under § 105.13(d)(1)(i) (relating to permit applications—information and fees), construction plans, specifications and design reports in sufficient detail to evaluate the safety, adequacy and suitability of the proposed dam, reservoir and appurtenant works, and a schedule indicating proposed commencement and completion dates for construction.
(3) For projects involving storage of fluids or semifluids other than water, information concerning the chemical content, viscosity and other pertinent physical characteristics of the fluid or semifluid impounded.
(4) Plans for proposed permanent monitoring of performance by instrument installations in the dam, including the purposes of the instrumentation. If no instrumentation is considered necessary, reasons for this engineering judgment shall be stated.
(5) A hydrologic and hydraulic analysis, submitted as a separate report, which includes the following:
(i) The size, shape and characteristics of the drainage basin.
(ii) Current precipitation data and precipitation distribution information as required by the Department.
(iii) Streamflow records.
(iv) Flood flow records and estimates.
(v) An incremental dam breach analysis, storage capacity and reservoir surface area for normal pool and maximum storage elevations.
(vi) Other hydrologic and hydraulic determinations necessary for the design and operation of the dam.
(6) For an existing dam, copies of the structure’s most recent inspection reports.
(7) An EAP if required under § 105.134 (relating to EAP).
(8) A manual documenting the operation and maintenance procedures for the dam.
(9) For projects impacting wetlands or exceptional value waters, or if the project requires 401 water quality certification, environmental assessment approval will be required under § 105.15 (relating to environmental assessment).
(b) The Department may waive the specific information requirements of this section in writing, if upon review of the request for Letter of Amendment or Letter of Authorization, the Department finds that specific information is not necessary to approve the project.
Authority The provisions of this § 105.89 issued under section 5 of the Dam Safety and Encroachments Act (32 P. S. § 693.5).
Source The provisions of this § 105.89 adopted January 7, 2011, effective January 8, 2011, 41 Pa.B. 219.
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