HILLSBOROUGH COUNTY PUBLIC WORKS TECHNICAL MANUALS AND SPECIFICATIONS 2 YEAR MANDATORY UPDATES (2017) COMMENTS & RESPONSES COMMENT / JUSTIFICATION

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1 County to modify County Staff 3.1 Add paragraph in this section requiring that pertinent redevelopment in water quality impaired basins be required to include water quality improvements sufficient to achieve a net improvement in water quality. County to modify County Staff 3.2 Add paragraph in this section requiring that pertinent redevelopment in water quality impaired basins be required to include water quality improvements sufficient to achieve a net improvement in water quality. County to modify b. 3 County Staff (b) Reword to encourage on-site retention perhaps: graded such that in a manner substantially equal in volume to predevelopment County to modify c. 4 County Staff (c) Remove "grassed" and replace with "stabilized with vegetation sufficient to stabilize soil." 13.1.B.3 has precedent for this. This allows for other forms of stabilization.

2 County to modify f. 5 County Staff (f) Replace "permanently grassed" with "permanently stabilized." 13.1.B.3 has precedent for this. This allows for other forms of stabilization. County to modify County Staff Alter to allow special requirements in impaired waters. Perhaps, Throughout unincorporated Hillsborough County are drainage basins which are subject to special stormwater management requirements based on County Master Plans, FDEP impaired water quality designation, and improvement projects or special studies. County to add new language under County Staff Revise section to require FEMA approval prior to County approval for any development within a floodway. County to modify c.1. 8 County Staff (c)1 Revise minimum required treatment to net improvement if in an impaired basin. 9 Website Submittal Request clarification or determination that off-site runoff routed into an on-site pond is not required to be attenuated for. This is specifically an issue in peak sensitive basins. Attenuation is required. It must be demonstrated through calculation to meet applicable County Criteria. No changes are recommended.

3 County to modify County Staff Remove "grassed" and replace with "stabilized with vegetation sufficient to stabilize soil." 13.1.B.3 has precedent for this. This allows for other forms of stabilization. County to modify County Staff Remove "grassed" and replace with "stabilized with vegetation sufficient to stabilize soil." 13.1.B.3 has precedent for this. This allows for other forms of stabilization. 12 County Staff Change to " provisions for establishing vegetation sufficient to stabilize soil on:" 13.1.B.3 has precedent for this. This allows for other forms of stabilization. County to modify Website Submittal a. 14 Website Submittal c. Section indicates only a DBI is acceptable as a control structure. Weir walls and other types of weirs are commonly used without special approvals from the County Engineer. This section should be revised to not preclude those structures. Request clarification be added to this section. On some projects a 3-inch orifice is not reasonable. This has traditionally been interpreted to mean the pipe must be 3 inches, but the hole cut in the cap on the pipe can be smaller. (No such criteria exists in small site design) County to modify B An orifice that is smaller than 3 inches is not feasible in terms of maintenance. No modification is proposed. County to modify County Staff (e) Change to " ponds directly to lakes or streams "

4 TTM provides guidance under County to modify County Staff Recommend requiring that stormwater MH s not to be installed in the wheel path. Manhole lid/cover should never be in the wheel path, they can be installed in the center of the travel lane. This item can be added to Section STM

5 County to update , Figure 10-1, Figure 10-2, and Table County Staff 10.0 Recommend adding and/or clarifying language in section to better describe the intent to use underdrain only when it is not feasible to raise roadway. Also recommend rewording items to clarify depths as they pertain to below the bottom of base at the low edge of pavement. Also recommend updating Certification to include stationing, deleting references to Townhome Subdivisions and providing a space for maintenance requirements.

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7 18 County Staff The density requirements of are not consistent with requirements in the TTM. Recommend referencing TTM Testing Schedule in lieu of providing the percent and method. County to update to reference Testing Schedule found in Appendix L of the Transportation Technical Manual for Subdivision and Site Development Project.

8 19 County Staff and LID uses ditches and small conveyances for storage and infiltration. Consider removing this paragraph or revising to not discourage LID/Green Infrastructure. County to add new language under to address issue. County to modify County Staff Change to "approved type of ground cover, " 13.1.B.3 has precedent for this. This allows for other forms of stabilization. 21 County Staff Recommend adding statement not allowing curb inlets to be placed within handicap drop curb locations or on curb returns. County to update

9 County to update 12-1 including deleting Note 3, including asphalt in Note 2 and making consistent with Section 10 edits. 22 Website Submittal Table 12-1 Section calls for the use of 0.5 foot of select sand(s) or special select sand (S+) when using soil cement or crushed concrete. This layer is not installed on projects and should be removed from the requirements. (3) also references this sand layer and requires approval from County engineer for asphalt base, which is a standard allowable alternate base material and should be approvable by the EOR.

10 23 County Staff This should be updated to reflect numeric nutrient criteria. The simplest way would be to require net improvement in impaired areas, since impairment status means the state has confirmed that the waterbody does not meet its Class III standard. Instead of requiring that it meet Class III standard (which I ve never seen enforced), require that, any water entering demonstrate equal or better water quality to preactivity conditions and net improvement in impaired basins. County to modify County to modify Change to (Ordinance # 14-4, as amended) 24 County Staff Alter to require improvement, impaired water bodies must demonstrate net improvement to reduce the expected increases in pollutant loading. Net Improvement can be calculated using the BMPTRAINS spreadsheet model. County to update County Staff Define reasonable assurance. County to modify a. 26 County Staff (a) Remove "usually ponds". Add paragraph describing other methods of treatment.

11 County to modify County Staff (a)7 Remove straw bale barriers no longer DOT approved BMP. County to modify Appendix B.3, C.1.d. 28 County Staff Appendix B.3, C.1.d Replace "grass" with "vegetation sufficient to stabilize soil." 13.1.B.3 has precedent for this. This allows for other forms of stabilization. County to modify Appendix B.3, C County Staff Appendix B.3, C.2. Change to include special requirements in impaired basins. Perhaps, Special requirements may be required within areas determined to be flood prone by a history of flooding and/or by stormwater management masterplans, adopted by Hillsborough County, and within areas identified as impaired by the FDEP. 30 County Staff New Appendix Recommend adding an Appendix which outlines the County s stormwater modeling review requirements. County to move the current Appendix D: Glossary to Appendix E and insert a new Appendix D: Stormwater Modeling Review Requirements.