Lee's Summit

A final quality assurance check was performed to determine whether the "First Plat Drainage Study" dated Mar. 3, 2017 meets the criteria listed in Section 5600 of the Design and Construction Manual. It appears only the areas upstream of D1 and D2 meet the criteria listed in Section 5600 for allowable release rates. The areas upstream of points A1, B1, and C1 do not appear to meet the criteria. The area upstream of point A1 appears to exceed the 2 year maximum release rate for the 2 year event, while all of the events are exceeded for the areas upstream of B1 and C1. This appears to be a significant issue, and will likely affect the design of the detention basins. It should be noted that the pre-development versus post-development analysis is no longer allowed in the City of Lee's Summit.

Sheet C124: The small detail "D.B. 15-2" does not appear to make sense. The FL in elevation is called-out as 935.50, which does not match what is shown on the larger detail "D.B. 15-2 and D.B. 15-3 Detail", nor the profile view of storm line 15.

Sheet C124: There appears to be no additional grading between the flared end section entering the detention basin, and the outlet structure, beyond leaving the area between these two points at existing grade. This does not appear to be equal to or greater than 2% slope.

Both Detention Basins: The MARC manual requires that a sediment forebay be constructed for utilizing a detention basin for 40 hour extended detention. This does not appear to have been included in the design.

Sheet C124: Where is the remainder of the plan view for the detention basin? Only a portion of the detention basin is shown. Please show the entire limits of the detention basin in plan view, along with the 100 year water surface elevation.

Sheet C124: There appears to be an encroachment to the 20 foot rule in the northernmost portion of the basin (i.e., a minimum of 20 feet between the 100 year water surface elevation in the basin, and any adjacent property). It is unclear if this rule is violated for those portions of the detention basin that are not shown on the plan view (see above comment).

Sheet C125: The detail for "D.B. 16-2" does not appear to make sense. The FL In elevation is called-out as 1022.00, contradicting the profile view.

Sheet C125: The profile view shows the flowline in elevation of 1012.00. If this is the case, why does the grading plan (shown on the same sheet) within the basin show it to be 1022 +/-? It appears there is a significant issue with the plans.

Sheet C125: A non-clogging outlet design was provided for the basin shown on Sheet C124. Why was none provided for this basin? A 4" orifice will likely clog during the first few rain events. The Design and Construction Manual requires the construction of non-clogging outlet structures, and this design appears to be deficient.

Sheet C125: Please show the extent of the 100 year water surface elevation within the detention basin. It appears the 20 foot rule will be met, but it is unclear without the extent of the design pool shown in plan view.

Sheet C125: At least 1/4 of the detention basin perimeter should be at a slope of no more than 5:1. It does not appear this condition is met for any portion of the detention basin, except perhaps in the northeast portion of the basin. This rule would also pertain to the detention basin shown on Sheet C124, but it appears this is met. Without the entire extent of the basin shown on Sheet C124, however, it is difficult to determine with certainty.

A Stormwater Pollution Prevention Plan (SWPPP) is required prior to approval of the plans. Two (2) copies are required.

ADA-accessible ramps must be installed along with the street improvements. There are notes contained on the plans (i.e., Sheets C106 through C113) stating that individual homebuilders will install these ramps. Please remove these notes. The ramps are considered part of the roadway improvements, since the roadway design is specifically linked to the ramps.

Sheets C115 and C116: There are insufficient details concerning the ADA-accessible way at intersections where there is a stop condition (i.e., stop signed), and an ADA-accessible ramp is being constructed. This includes the following intersections in a stop condition: 1) Arboridge Dr. and Arbor Valley Terr., 2) Arboridge Dr. and Arbor Valley Dr., 3) Arbor Valley Dr. and Arborwood Dr., 4) Arboridge Dr. and Arbor Falls Dr., 5) Arborwood Dr. and Arbor Falls Dr., 6) Arbor Tree Dr. and Arbor Falls Dr., 7) Sugar Tree Dr. and Arboridge Dr., and 8) Sugar Tree Dr. and Arbor Tree Dr. In other words, The upper left hand corner of Sheet C115, the bottom middle inset of Sheet C115, and all of the ramps on Sheet C116.

The details requested in the above comment can be provided in several ways. Cross-slope call-outs should be specified across the intesections under stop control (i.e., stop signed), with a design slope of no greater than 1.5%. The width should be a minimum of 4.0 feet. An example of the level of required detail is provided with this comment letter, but should not be construed as the only way to provide this level of detail.

Please be aware that the incorporation of these design features for the ADA-accessible paths across the stop controlled interersections will likely require new profile views of the roadway sections.

Sheet C124: Is there at least 1.0 feet of freeboard between the 100 year water surface elevation in the detention basin, and the top of the dam? It does not appear this is the case. It appears it is short by a few inches.

The basement type (e.g., standard, daylight, and walkout) was not provided on the Master Drainage Plan. This is required by ordinance.

The ADA ramp design and intersection details associated with the intersections along Hook Road are subject to comment and modification based on pending Hook Road improvement plan review.

ADA-Ramp Details: It appears Section 5300 of the Design and Construction Manual was not consulted in the design of the ADA-accessible ramps. In most cases, a 2.0% cross-slope was designed as evidenced by a spot-check of the proposed elevations, and running slopes were based on 1:12 slope while the City requires a design standard of 7.5%. Please see Table LS-5 of Section 5300 for specific "Design Slopes" shown on the table. The City requires a design cross-slope of 1.5%, and a running slope of no more than 7.5%.

There were several instances where the tactile warning strip was greater than 5 feet from the curb line. The maximum distance between any point on the tactile warning strip is 5 feet.

There appears to be a misconception of what is required at the ramp. While it is acceptable to construct the ramp prior to the "landing" (i.e., a turning space?), typically this is not the case. In typical situations, the ramp extends to the curb line, with appropriate turning spaces provided if there are turns to the left or right. These turning spaces must be designed with no more than a 1.5% slope in all directions.

Sheet C119: The detail at Arboridge Dr. and Arbor Valley Dr. does not appear to show an appropriate turning space. A 4 foot minimum turning space is required, unless a curb is present behind the turning space, in which case a 5 foot minimum clear distance is required for the turning space. It appears only 3 feet is shown.

Sheet C119: It is not clear what is being proposed for the "receiver ramps" on the north side of Arbor Valley Terr. From the elevations shown, it appears there is no ramp at these locations. It appears the sidewalk adjacent to the ADA-accessible ramps are lower than the curb and gutter, which is generally not allowed. If the ramps are constructed in this way, drainage will be directed to the ADA-accessible ramp, which is not a desirable situation.

Sheet C119: Tactile warning strips were not shown on the ADA-accessible "receiver ramps" discussed above.

ASheet C119 and C120: Notes at the bottom of the sheet are not correct. Ramp running slope should be designed for a maximum of 7.5%. A turning space is required at all directional changes. "Landings" are not necessary.

Please be aware that the design details specified in Section 5304.8 will be required going forward. In other words, for purposes of this review they are not required but in the future, will be required.

Master Drainage Plan: The note concerning the installation of side yard swales for the lots 87 through 94 is a good start, but please show this graphically on the Master Drainage Plan. Perhaps an asterick and note with a drainage arrow?

Master Drainage Plan: The scale appears to be in error. Is this a 50 scale?

Sheet C129: DB 15-2 appears to have been mislabeled on the detail inset. Is this DB 16-2?

It did not appear the ADA-accessible ramps near Hook Rd. were detailed. Please provide details for the construction of these ramps.

Sheet C112: It appears there are incorrect references to the ADA-accessible ramp details. Sheet C120 is called-out, but it appears that in most cases, it is actually Sheet C119?

All Sheets Containing Sidewalk and ADA-accessible Ramps: Since the plans call for installation of sidewalk and ADA-accessible ramps during construction of the subdivision, these features will be required as part of the subdivision construction. If this is not the case, then sufficient notes must be provided stating that these features will be installed "by others" or equivalent language. Please be aware that even though the City does not necessarily require the installation of these features during sudvision construction, all areas adjacent to common area tracts must be constructed with the subdivision. In addition, the City has no issue with construction of all of these features with the subdivision if the developer desires.

Verify adequate intersection sight distance is available for Arbor Tree Dr. at Arbor Valley Ter, particularly in the southwest direction where a crest of 12K curvature is designed. It appears the crest may be blocking visibility of the departure lane from the side street.

Provide pavement marking plan for the improvements along Hook Road.

Provide signing plans depicting all signs and locations.

Include City standard details for pavement markings.

Roadway improvements along Hook Road are missing plan details (e.g. station, offset, dimensions, etc.).

The right-turn lanes along Hook Road should be 150' in lenght plus 150' taper. One turn lane appears too long, the other too short and the taper for both is less than 150' as shown.

The left-turn lanes along Hook Road should be 200' in length plus 150' taper with reverse curves. Both appear too short.

The through lane transition for the widening of Hook Road shall meet or exceed a transition distance based on the lane transition formula considering the offset and speed limit. The transition should not occur through the intersection. Recommend no transition between the proposed intersections due to the close proximity; rather maintain a three lane section in this area.

Sheet C103: Please clean-up the various strikeovers on this sheet.

Sheet C103: Please provide a north arrow.

Sheet C103: ES 15-2 appears to be labeled wrong. Should this be DB 15-2?

It appears the off-site improvements to Hook Road were presented as a "concept plan" rather than final construction documents. Complete plans will be necessary either contained within this plan set, or separate from this plan set.

Please define "P.O.S."

Sheet C103: Please show the ADA-accessible ramps north of Arborwood Dr., and Arbor Tree Dr.

Sheet C107: Please show the ADA-accessible ramps north of Arborwood Dr. and Arbor Tree Dr.

General Comment Concerning ADA-Accessible Ramps: A specific detail(s) is needed for each ADA-accessible ramp that is either constructed with this project, or constructed as part of the bulding permit process. Please refer to Section 5300 of the City of Lee's Summit Design and Construction Manual for specific details. The City has adopted the draft PROWAG standards which do not follow the KCAPWA standard drawings. If possible, please avoid "wings" in the design of these ramps, and ensure that 1.5% cross-slope is called out for construction of the ramps. Please provide the minimum design information requested in Sectio 5300 of the Design and Construction Manual.

Sheet C111: Please correct the strikeover errors on this sheet.

Sheet C112: Please correct the strikeover errors on this sheet.

General Comment Concerning ADA-Accessible Ramps: Please label each ADA-accessible ramp, and provide a reference to the detail sheet showing the design of the ramp. As discussed previously, please avoid the use of wings to the extent possible.

Sheet C114: Please correct the strikeovers on this sheet.

Sheet C114; As discussed in the previous comment, the Hook Road improvements, appar to be a concept plan. These plans will need to be upgraded to construction plans showing exact dimensions, pavement details, grading details, etc. These plans can either be a part of this plan set, or submitted as a separate plan set.

Sheet C114 through C116: Please label all ADA-accessible ramps, with corresponding reference notes calling-out the detail and sheet number.

Sheet C115: ADA-accessible ramps appear to be missing on detail 1, 2, 3, and 4. Only one (1) ADA-accessible "receiver" ramp is required for each of these details.

Sheet C116: ADA-accessible ramps appear to be missing on detail 2, 3, 5, and 6. Only one (1) ADA-accessible "receiver" ramp is required on each of these details.

Sheet C118: The stormwater report appears to show the 10 year water surface elevation within the northern detention basin as 1023.79. The 10 year hydraulic grade line within the pipe at ES 3-1, however, is shown as significantly lower than this elevation. What assumptions were made when performing the calculations? It would appear the 10 year and 100 year hydraulic grade lines within the basin were not taken into account.

Sheet C118: The same comment (above) would pertain to Storm Line 5. The stormwater report indicates the 10 year hydraulic grade line is 1003.70, but the 10 year hydraulic grade line at ES 5-2 is significantly lower.

Sheet C119: FI 6-3 and FI 6-5 show field inlets with what appears to be a lack of any local sump. How will stormwater be directed to these field inlets?

Sheet C120: The note in the plan view for FI 6-3 appears to be labeled incorrectly. A curb inlet is called-out.

Sheet C121: Field inlets 9-4 and 9-5 appear to be lacking a local sump. How will stormwater be directed to these field inlets?

Sheet C121: Please correct the two (2) strikovers on this sheet.

Sheet C122: FI 10-2 appears to be lacking a local sump. How will stormwater be directed to this field inlet?

Sheet C123: ES 14-1 shows what appears to be a hydraulic grade line significantly lower than the 10 year water surface elevation within the detention basin. The stormwater report appears to show this elevation as 1023.79.

Sheet C123: Please correct the two (2) strikover errors on this sheet.

Sheet C124: Please show the 100 year hydraulic grade line within storm line 15.

Sheet C124: It appears the detail for DB 5-2 and 5-3 are labeled incorrectly. Are these DB 15-2 and 15-3? Finally, a label and leader point to DB 5-3, and it appears this should be DB 15-3.

Sheet C124: It is unclear how the southwest basin will drain in 40 hours. A standpipe appears to project 3 feet into the air, with no provision for slow drawdown.

Sheet C124: Please provide additional views of the "concrete box inlet protection" either by additional section views, plan views, isometric views, etc. It is difficult to determine what is being constructed.

Sheet C124: If using the standpipe option, an anti-vortex plate and cage should be installed at the top of the pipe to eliminate a vortex developing during storm events.

Sheet C124: An easement is shown for the southwest detention basin outlet structure and outflow. This should be eliminated since this is a private structure and pipe. This should also be updated on the Final Plat.

Sheet C124: Please correct the strikeover error on the note on the lower right (i.e., DB 15-2 label).

Sheet C125: No details were provided for DB 16-2.

Sheet C125: Please show the 100 year hydraulic grade line for Storm Line 16, and please label the profile view as "Storm Line 16".

Sheets C127 and C128: Please refer to the comments concerning the 10 and 100 year water surface elevations within the two (2) detention basins. The calculations do not appear to be valid based on the elevations within the two (2) detention basins.

Sheet C129: Please label all swales with the word "swale" or "emergency overflow swale".

Sheet C129: Contour lines are not clear in the region of Lot 81, 82, 76, and 77. Is this a sump? If so, where is the emergency overflow swale?

Sheet C129: Please call out the 100 year water surface elevations within the detention basins.

Sheet C129: It would appear an additional field inlet is warranted at the northeast corner of Lot 91. This appears to be a significant drainage area along the rear of these lots, without any stormwater management other than sheetflow.

Sheet C129: Please correct the first note as "Minimum Building Opening Elevation" rather than "Minimum Basement Opening Elevation."

Sheet C129: Please correct the various strikeover errors on this sheet.

Sheet C130 and C131: Please provide a specific design for the sediment traps and sediment basins. How will stormwater be directed during storm events? As shown, it would appear there is no provision for directing "clean" stormwater around the basin/traps, but rather, the basin/traps will fill up without any provision for routing the stormwater (i.e., there are no outlets?).

Sheet C135: The trenching detail for stormwater pipe only reflects installation practices for pipe outside of the right of way and paved areas. Please revise the standard detail for areas within right of way and beneath pavement.

Sheet C135: Please remove the trenching detail for CMP since it will not be used on this project.

Sheet C135: The underdrain detail shows geogrid within the pavement design. It was our understanding this would be flyash stabilized subgrade.

Sheet C124: Rip rap is shown at the end of Line 15. However, the west edge of the rip rap ends abruptly at the property line. Is there a way to move the end of pipe back sllightly to construct a more "standard" rip rap area in terms of plan view?

Sheet C124: The 10 and 100 year WSE listed on the left side of the sheet do not appear to match what is shown in the stormwater report.