| Review Type |
Outcome |
Est. Completion Date |
Completed |
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Engineering Review
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Corrections
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11/14/2016
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03/23/2017
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Gene Williams, P.E.
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Engineering Review
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Corrections
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03/22/2017
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03/23/2017
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Gene Williams, P.E.
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Corrective Action Required
Sheet C.402: It appears the sanitary sewer manhole frame and lid is not correct. This appears to be a frame and cover for a slab top installation. Wouldn't this frame and cover be a Clay and Bailey 2014OR or equivalent?
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Corrective Action Required
Sheet C.402: Please label the typical "Gravel Parking" as "Gravel Parking Area Restoration Detail" to match the note included in the plan view.
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Corrective Action Required
Sheet C.402: Manhole A-0 appears to be shown 9 inches above grade. Please revise as appropriate to meet the request of the property owner concerning the installation of all manholes "at grade".
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Corrective Action Required
Sheet C.402: Please show the existing City manhole which is buried beneath ground level on the profile view, with a note stating that this manhole will be raised to grade. Depending on the required distance needed to raise this manhole to grade, it may be necessary to install a new cone section if adjusting rings are greater than 12" in height.
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Corrective Action Required
Sheet C.403: Manhole A-4 and A-5 are now shown 2 to 5 feet below grade. Please correct.
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Corrective Action Required
Sheet C.403: The 100 year hydraulic grade line at manhole A-6 to points downstream does not appear to be correct. The line is shown beneath the pipe, and there is another curious lines shown beneath the pipe between manhole A-5 and manhole A-4.
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Corrective Action Required
Sheet C.404: Please drop the flowline in/out elevation of manhole A-9 by 0.20 feet. Also, please drop the flowline in/out elevation of manhole A-10 by 0.10 feet. This will help achieve a greater slope in the pipe, greater than the minimum slope of 0.24%.
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Corrective Action Required
Sheet C.404: Please raise manhole A-12 slightly, as shown on the previous drawing received on Mar. 2nd. It appears this version has changed slightly to the point where the manhole is slightly buried beneath proposed grade.
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Corrective Action Required
Sheet C.404: What is the plan for "bank stabilization" at station 26+00? A note is provided, but no supporting design is supplied. A detailed design should be supplied, including any turf reinforcement mat, etc.
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Corrective Action Required
Sheet C.406: This sheet was provided in order to show details for construction of the Coir Log stream stabilization measures at the Cedar Creek sanitary sewer crossing. The upper detail "Coir Log Alignment (Plan)" does not appear to be a plan view. It is unknown how far the turf reinforcement mat will be installed. Erosion control blanket is called-out in some instances, where turf reinforcement mat is called-out in others. In other words, we need a site-specific plan for installation of the Coir Logs, the TRM or ECB, a plan view showing a plan view of the design, and any other views necessary to show a contractor and inspector what they are expected to construct and inspect.
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Corrective Action Required
Sheet C.404: The same comment above would apply to streambank stabilization near station 25+66. Simply providing a note stating "bank stabilization area" with no supporting design or lacking a separate sheet for a detail is not adequate.
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Corrective Action Required
It appears the Engineer's Estimate of Probable Construction Costs is missing the following items: 1) manhole adjustment to grade (see comments concerning the buried manhole), 2) please separate-out the two (2) different concrete encasements, 3) turf reinforcement mat, erosion control blanket, etc., 4) streambank stablization measures using Coir Logs, TRM, ECB, etc., 5) all other streambank stabilization measures installed upstream, and 6) any diversion dikes to enable construction of the crossing at Cedar Creek.
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Engineering Review
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Corrections
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11/04/2016
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11/04/2016
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Gene Williams, P.E.
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Corrective Action Required
Manhole A-2 is shown extending six (6) feet above the finish grade. In accordance with the Design and Construction Manual, manholes shall be fitted with watertight ring and bolt-down assemblies with neoprene gaskets where the manhole extends greater than four (4) feet above finish grade. Please provide sufficient notes and a detail drawing showing these features.
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Corrective Action Required
Please submit a Floodplain Development Permit with the required attachments.
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Corrective Action Required
The City has concurred with the No-Rise Study. Please submit a No-Rise Certificate for this project.
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Corrective Action Required
Please be aware that easements must be acquired prior to approval of this project.
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Corrective Action Required
Please be aware that United States Army Corps of Engineers (USACE) approval is required prior to City-approval of this project.
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Corrective Action Required
The Engineer's Estimate of Probable Construction Costs dated Oct. 21, 2016 appeared to be missing the following items: 1) sanitary pipe encasement at the two (2) locations shown on the plans, in accordance with the details, including all steel reinforcement, excavation, forming, etc., 2) diversion dikes within the stream that are necessary to construct the above sanitary sewer crossing, 3) bolt-down frame and lids, 4) watertight seals, and 5) streambank stabilization measures.
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Engineering Review
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Corrections
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10/14/2016
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10/14/2016
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Gene Williams, P.E.
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Corrective Action Required
Please refer to comment #1 in the previous comment letter dated Sept. 19, 2016. The "Encasement Profile" shown on Sheet C.405 does not appear to match what is shown on Sheet C.402 or Sheet C.204.
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Corrective Action Required
Please refer to the markup version of Sheet C.405 provided as an attachment to this comment letter. Specific dimensions and materials should be specified for the encasement rather than referring to a table. This would include thickness of the concrete around the pipe, KCMMB concrete mix, etc.
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Corrective Action Required
Please refer to the markup version of Sheet C.405 provided as an attachment to this comment letter. Separate section views should be provided at the ends and the middle of the encasement.
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Corrective Action Required
Please refer to the markup version of Sheet C.405 provided as an attachment to this comment letter. Additional depth at each end of the encasement detail appear warranted (e.g., 30"?). A low flow "trough" appears to be warranted at the middle of the crossing.
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Corrective Action Required
Please refer to the markup version of Sheet C.405 provided as an attachment to this comment letter. Addtional length of the encasement on each side appears warranted near station 2+92. This is due to what appears to be a small tributary at this location.
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Corrective Action Required
Sheet C.404: It appears bank stabilization is warranted for manhole A-13 and manhole A-12. The alternative would be to extend the length of the crossing so the manholes are outside of the streambank. Please be aware that the specification of "rip rap" would not be sufficient to protect these manholes, so a more robust design would be necessary.
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Corrective Action Required
Sheet C.402: Stream restoration is specified on the plan view for areas to the east and west of the stream crossing, and the notes refer to Sheets C.406 and C.407. Sheets C.406 and C.407 are generic stream restoration details, and additional site-specific design details are needed. Where are these measures going to be implemented? What are the planned dimensions? Where are they going to be installed?
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Corrective Action Required
Sheet C.401: A note is provided on the plan view which states "Floodway Grading Plan". Where is this plan? The note points to the stream, with no proposed contours. Will the existing grades be changed on the sides of the stream?
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Corrective Action Required
General Comment on the No-Rise Study: We are awaiting additional information from the engineer concerning the HEC-RAS model to make a decision concerning the no-rise certificate. At this time, the City believes the general concept of the design will meet the requirements of a no-rise condition.
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Corrective Action Required
General Comment: Easements will need to be acquired, United States Army Corps of Engineers (USACE) permits submitted, No-Rise certificates submitted, and a City-issued Floodplain Development Permit issued prior to approval of the plans.
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Corrective Action Required
General Comment: If the additional information needed to confirm or not confirm the No-Rise condition reveals that slight adjustment to the plans be made, then additional comments on the plans may be forthcoming. The City anticipates that this would be limited to additional grading along the streambank(s) to achieve a true No-Rise condition.
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Engineering Review
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Corrections
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09/19/2016
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09/19/2016
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Chris Hughey
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Corrective Action Required
Sheet C.402: The "Encasement Profile" does not appear to match what is shown on Sheet C.204.
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Corrective Action Required
The design of the concrete slab and encasement is incomplete.
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Corrective Action Required
The temporary construction easement was not shown. The response to comment letter states this is within a "hatched" area, but no such "hatched" area was found on the plan sheet(s). There was a shaded area, but it was not continuous and not defined in terms of a legend or other identifiable symbol. The temporary easement should be clearly defined, and on one plan view rather than in pieces.
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Corrective Action Required
Sheet C.402: The plan view in the upper left hand corner did not include a north arrow. In addition, the north arrow on the upper right "Sanitary Plan and Profile View" appears reversed. Please show this in one plan view, and one north arrow, and please clearly define the limits of the temporary grading easement.
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Corrective Action Required
Scott Edgar's Comments: Creek patterns and profiles and geometry are formed by the flowing water and sediment load delivered to the creek. these characteristics are created in a way to be very efficient at transporting the water and sediment load. When changes occur in the watershed, creeks adapt and change to accommodate the new flow regimes. Therefore, they move and change slightly all the time in urban settings. The basic parameters, however, stay within ranges for specific watersheds. There is concern that a concrete mat as proposed does not match the characteristics of any stable stream. The stream will move around the obstruction to the west as proposed. Weirs in streams must match a stable cross section, or the stream will work around the obstruction.
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Corrective Action Required
Scott Edgar's Comments: The concrete mat is 80 feet by 90 feet by one (1) foot thick. There are questions concerning the construction details, the fact that the grading shown does not match the spot elevations shown on the concrete mat, the fact that the mat has 1.5 feet of elevation change on the outside of the meander bend and will lead to migration of the stream to the west, the fact that the floodplain shelf should be on the outside of the meander bend only, with armoring on the outside and/or weirs placed to maintain a stable cross section, and the fact that the sides of the mat lack any footings which will most likely lead to scour, undercut, and failure of the mat.
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Corrective Action Required
Scott Edgar's Comments: Proposed grading is shown on the bottom of the creek bed. How will this occur in practice?
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Corrective Action Required
Scott Edgar's Comments: There appears to be no geomorphic assessment of the stream. There appears to be a solution without any regard to the geomorphology of the project.
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Corrective Action Required
Scott Edgar's Comments: What is the flow capacity and flow velocity of the mat both upstream and downstream?
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Corrective Action Required
Scott Edgar's Comments: Has there been a comparison of stream power in the existing channel versus the new mat profile?
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Corrective Action Required
Scott Edgar's Comments: The HEC-RAS data output appears to include only one (1) model run. The FEMA MT-2 would require additiona model runs. There is nothing to compare the model run against (i.e., duplicate effective model).
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Corrective Action Required
Scott Edgar's Comments: There appears to be a high erosion potential of soil and backfill beyond the mat when the stream is outside it's banks.
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Corrective Action Required
Scott Edgar's Comments: It would appear the grading design should be revised to include a low flow shelf to minimize stream energy and discourage overbank flooding. The design should seek to mimic a natural, stable stream.
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Corrective Action Required
Scott Edgar's Comments: The design should be based on several stage/flow scenarios rather than one (1) design flow.
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Corrective Action Required
Scott Edgar's Comments: Hard structural armoring is only strong for the first years of a project. Natural solutions are weakest, but grow stronger each year and provide for minimal maintenance costs to the City. It appears this was not considered in the design.
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Corrective Action Required
It would appear a meeting would be beneficial to discuss these comments. As designed, it is the opinion of the City that the solution shown in the plans will not be effective in iminimizing future costs to the City in terms of maintenance, and may lead to a failure at the stream crossing.
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Engineering Review
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Corrections
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09/07/2016
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09/07/2016
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Gene Williams, P.E.
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Corrective Action Required
Please see comment #11 in the previous comment letter dated July 26, 2016 (hereinafter referred to "comment letter"). This comment was not addressed since there are several additional cross-sections and other information requested by Scott Edgar in an email dated Sept. 2, 2016.
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Corrective Action Required
Please see comment #12 of the previous comment letter. Manhole A-0 does not appear to be one (1) foot higher than the base flood elevation.
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Corrective Action Required
Please see comment #13 of the previous comment letter. The reference calls out "see Sheet C.405", but this sheet only includes a standard detail for concrete encasement. As we have stated in previous meetings, this is a special design and a standard detail for concrete encasement will not be adequate.
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Corrective Action Required
Please see comment #19 of the previous comment letter. The temporary construction easement for grading was not shown on the plans for the area to be graded in the vicinity of the stream crossing.
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Corrective Action Required
Please see comment #20 of the previous comment letter. A formal waiver request was not provided.
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Corrective Action Required
Please see comment #21 of the previous comment letter. According to the response to this comment, these plans have not been finalized by the structural engineer. Without a final plan for the design of the concrete slab and sanitary sewer crossing, it is impossible to review the plans.
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Corrective Action Required
Please see comment #31 of the previous comment letter. The response to comments stated this had been corrected, but it appears it has not. The fall at these manholes (i.e., A-12 and A-13) is the same as the last submittal. A minimum of 0.5 feet is needed.
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Corrective Action Required
Please see comments #34, #35, #36, and #37 of the previous comment letter. USACE permits, floodplain development permits, no-rise certification for the new concrete slab structure, and acquisition of sanitary sewer easements will be a condition of approval of these plans.
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Engineering Review
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Corrections
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07/26/2016
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07/26/2016
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Gene Williams, P.E.
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Corrective Action Required
Sheet C.001: Are there any wyes being installed with these plans? The notes at the bottom right hand corner would seem to indicate they are, but it does not appear there any to be constructed for this project.
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Corrective Action Required
A sanitary sewer analysis should be performed. It should include the entire drainage basin, and take into account the receiving sewer, including hydraulic grade line of the receiving sewer.
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Corrective Action Required
How will the construction site be accessed? It does not appear any provision was made for site access.
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Corrective Action Required
Sheet C.052: Is there any bank stabilization measures to be performed? it would appear this is required.
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Corrective Action Required
Sheet C.401: Property ownership information must be provided on this sheet.
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Corrective Action Required
Sheet C.401: Please show the limits of Cedar Creek, along with a label denoting "Cedar Creek".
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Corrective Action Required
Sheet C.401: Please show the limits of the 100 year floodplain.
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Corrective Action Required
Sheet C.401: Please provide labels denoting the "existing Cedar Creek interceptor".
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Corrective Action Required
Sheet C.401: Please show the location of the smaller tributary from manhole A-15 to manhole A-1.
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Corrective Action Required
All Profile Views of Sanitary Sewer: Please show the hydraulic grade line within the pipe and manholes.
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Corrective Action Required
Sheet C.402: The project must be designed as a "no-rise" condition (i.e., no increase in the 100 year base flood elevation will be allowed). It is difficult to determine whether this will be possible, given the fact that the concrete encasement will extend two (2) feet higher than the existing stream bed.
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Corrective Action Required
Sheet C.402; Please show the limits of the 100 year base flood elevation on the profile view. Manholes must be a minimum of one (1) foot above the 100 year base flood elevation.
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Corrective Action Required
Sheet C.402: Concrete encasement should be extended further between manhole A-2 and manhole A-1. This is due to the fact that Cedar Creek will likely meander in course over the years. Ductile iron with restrained joints should be clearly specified. The drawing should clearly reference the detail to use for the concrete encasement, and if using SAN-7, T must be equal to or greater than 8 inches. Steel reinforcement equaling or exceeding the steel shown on SAN-7 must be shown.
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Corrective Action Required
Sheet C.402: The fall between incoming and outgoing flowline elevations at manhole A-2 should be increased to 0.5 feet due to the high degree of deflection angle.
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Corrective Action Required
Sheet C.402: The fall between incoming and outgoing flowline elevations at manhole A-1 should be increased to 0.5 feet due to the high degree of deflection angle.
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Corrective Action Required
All Sheets: Are there any coordinates that can be provided? Please provide these.
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Corrective Action Required
Sheet C.402: The profile view of the new sanitary sewer manhole shows a flowline "in" of 700.00'. Is this a typographical error?
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Corrective Action Required
Sheet C.402: The pipe slopes shown on the profile do not appear correct (i.e., manual calculation shows a difference between A-3 and A-2, A-1 and A-0, and A-0 to the existing sanitary sewer manhole #27-189. Please correct as appropriate.
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Corrective Action Required
All Sheets: Please show the proposed easements on the plan view. Label the easements, and the property owner(s) whom the easement must be obtained.
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Corrective Action Required
Sheet C.402: The placement of the sanitary sewer above the streambed will require a waiver to the Design and Construction Manual. A formal waiver request will be necessary.
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Corrective Action Required
Sheet C.402: Plans were missing on how this design will be able to be constructed, yet preserve the "no-rise" requirement during the 100 year event. Will Cedar Creek be widened to increase flows in this area? Without plans showing how this will be performed, it is difficult to determine whether the project will be possible.
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Corrective Action Required
Sheet C.403: Manhole A-8 shows what appears to be erroneous flowline "in" elevations.
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Corrective Action Required
Sheet C.403: Manhole A-7 shows what appears to be erroneous flowline "in" and flowline "out" elevations.
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Corrective Action Required
Sheet C.403; Manhole A-6 shows what appears to be erroneous flowline "in" elevations.
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Corrective Action Required
Sheet C.404: Pipe slope between A-14 and A-13 appears to be erroneous on the profile view. Our calculations show 7.24% rather than 10.53%.
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Corrective Action Required
Sheet C.404: The tributary stream crossing is too shallow. Please see the Design and Construction Manual for specific depth requirements. The depth requirements are dependant upon the presence of bedrock, or lack thereof. If bedrock is two (2) feet or more below the bottom of the stream, three (3) feet of cover is required. This measurement is made to the top of the concrete encasement.
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Corrective Action Required
Sheet C.404: Provide a specific reference to the drawing number for the concrete encasement, and specify ductile iron with restrained joints.
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Corrective Action Required
Sheet C.404: Manhole A-12 and A-13 are shown at the edge of the streambank. Please move these manholes further back from the streambank to mitigate exposure concerns (i.e., erosion of the streambank and subsequent manhole exposure).
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Corrective Action Required
Sheet C.404; The pipe slope shown on the profile view between manhole A-12 and A-11 appears erroneous. Our calculations show 2.73%.
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Corrective Action Required
Sheet C.404: The stationing for manhole A-11 appears erroneous compared to the plan view. In addition, it does not appear that 0.20 feet of fall was provided for this manhole.
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Corrective Action Required
Sheet C.404: The fall at manhole A-12 and A-13 must be increased to 0.50 feet to account for the large deflection angle.
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Corrective Action Required
Sheet C.404: The plan view shows what appear to be "on-site" sanitary sewer lines to the south of manhole A-15. If so, please label these.
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Corrective Action Required
Sheet C.405: It does not appear that drop manholes, casing carrier pipe, or building sewer stubs will be used on this project. Please delete them if they are not used. The same comment would apply to shallow manholes. If shallow manholes are not being used on this project, then please delete this detail.
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Corrective Action Required
United States Army Corps of Engineers (USACE) permits, including wetlands permits, may be required for this project prior to approval.
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Corrective Action Required
A floodplain development permit would be required for this project for any fill within the floodplain.
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Corrective Action Required
Approval of this project is contingent upon the ability to certify that the design will not increase the base flood elevation after installation. This includes any areas upstream (and downstream) of the project. It is uncertain how this will be accomplished because the sanitary sewer encasement is already being proposed two (2) feet higher than the bottom of the streambed, and no engineering plans were provided showing how the adjacent streambed would modified to prevent a rise in the base flood elevation.
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Corrective Action Required
Approval of this project is dependant upon the acquisition of sanitary sewer easements across the properties shown on the revised "Overview Sheet".
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