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HomeMy WebLinkAboutResponse to Staff Comments 1 RESPONSE TO COMMENTS Project: CASTLEGATE II SEC 200 (FP) - 11 00500037 ENGINEERING COMMENTS NO. 1 (Final Plat and Construction Documents) " . P - ase pay outstanding development permit fee of $11,434.07. oted. The outstanding fee will be paid prior to the issuance of the Development Permit. he Oversized Participation Request is currently being processed, I hope to have it to legal for review by April 12th and on the April 28 Council Agenda for approval. Noted the intent is to submit a blanket easement, please submit easement dedication OF The easement documents have been submitted for consideration with the Final Plat. Please submit letter of acknowledgement. The Letter of Acknowledgement is included with this submittal. 5. PI: .se provide documentation and certification concerning permitting through e United States Corp of Engineers. If this project falls under a Nationwide Permit please specify which permit and how you are meeting its specific thresholds. In addition please identify if this project requires notification or further United States Corp of Engineers involvement. A Pre - Construction Notification has been forwarded to the USACE indicating that the project falls under NWP #29 (Residential Developments). This permit allows up to 0.5 acres of fill in Waters of the US. A study prepared by CSC Engineering & Environmental concluded that 0.25 acres are being filled under our current plan. The permit also states that a maximum of 300 if of stream can be impacted, but that requirement can be waived by the Administrator for ephemeral or intermittent streams. This project exceeds 300 feet, so we are requesting that requirement be waived. We are awaiting a response from their office. A copy of the PCN is included with this submittal. Please provide documentation concerning authority to perform the proposed off - site drainage improvements on the existing Castlegate Common Area. A letter concerning authority to perform the proposed off -site drainage improvements is included with this submittal. . As some sheets illustrate the needed striping and others do not, please provide a stand -alone striping plan sheet. A new sheet has been added to the plan set showing the striping, signage and lighting details. Please provide a single sheet striping plan, similar to details found on Sheet 7. A new sheet has been added to the plan set showing the striping, signage and lighting details. . (Sheet 2) Typo on "Existing Outlet Structure Note" reference to Sheet 8 not Sheet 9? The note has been corrected. f . (Sheet 2) Please provide language from the fire department for specific loading capacity of the proposed Temporary Emergency Access Road. A note has been added. . (Sheet 3) Please specify reinforced concrete box culvert design standard ASTM C -789 or ASTM C -850. The two ASTM standards are no longer used. They have been replaced by C -1433 which has two classifications for box culverts depending on the depth. A note requiring compliance with this standard has been added. . (Sheet 3) Is the intent for the 10 foot sidewalk to be built right up to the rear fences of Lots 1 thru 12 of Block 2? Yes, that is the intent. . (Sheet 3) Victoria mis labeled as 48' B - B. The note has been corrected. 4. (Sheet 4) V toria mis labeled as 48' B - B. The no • as been corrected. .. (Storm Pipe) RCP is required under public pavement. Where storm sewer is not under pavement, HDPE with cement stabilized sand as in the structural trench requirements per detail D3 -02 is always utilized is the minimum acceptable. Note that design engineers are to specifically design and seal the HDPE detail specific to each set of plans and site. In general we require structural trenching within 5 ft of public back of curbs or under public sidewalks. HDPE is acceptable under sidewalks and if the pipe is completely behind the curb. All pipes that lie under a road are now labeled as RCP. The area around the corner of Toddington and Odell was revised such that the junction boxes are outside of the roadway, and consequently, we are now able to use HDPE pipes in this area. Additionally, we have added trenching details for HPDE pipes. . (Storm Pipe) In several locations the storm pipe and water mains are run parallel in cross proximity of each other. Please provide additional clearance for means of future access and maintenance. This may require a narrow easement dedication in the fronts of these lots. Along Toddington Lane, Hadleigh Lane, and W.S. Phillips Parkway, the water lines were relocated and easements widened to allow for easier maintenance of the respective mains in addition to the storm sewer. 1 . (Sheet 12) Storm Pipe 231, structural trenching required within 5 feet of pavement. Structural trenching is now included for Storm Pipe 231 (Sheet 13) Storm Pipe 212, structural trenching required within 5 feet of pavement. Structural trenching is now included for Storm Pipe 212. 1 . (Sheet 14) Please identify steel casing in plan view, verifying that the steel casing will spans the future build -out of WS Phillips Pkwy. The steel casing was lengthened slightly to ensure that it will span the future build out of W.S. Phillips Parkway. . (Sheet 14) Steel casing for 8 inch main should be 16 inch not 14 inch. 16" steel casing was used in lieu of 14" in all places where casing is needed for an 8" water line (see W -1, W -2, & W -3). . (Sheet 14) Please note end caps on both steel encasements. In all places that a steel casing was used the use of end caps was noted. (Sheet 15) Please encase the water main as Victoria is classified as a major collector. The water line crossing Victoria has been encased as requested. Also, the re- design of the intersection of this water line (W-2) with W -1 may be noted as a result of the placement of this casing and the requirements of comment #16. . (Sheet 15) Valve missing between Sta. 0 +00 and Sta. 9 +43. A valve was added at station 3 +63.27 of water line W - 2. . (Sheet 15) Sta. 8 +50, check water and sanitary sewer conflict alignment. No co ict occurs. (Sheet 17) Valve missing between Sta. 0 +00 and Sta. 9 +69. A valve was added at station 4 +00 of water line W - 6. . (Sheet 18) Valve missing between Sta. 0 +00 and Sta. 8 +84. A valve was added at station 5 +00 of water line W - 7. (Sheet 19) The steel casing diameter for an 8 inch main is 16 inches and please note the use of end caps. The casing has been modified to 16in and the use of end caps has been noted. (Sheet 21) In areas where the sanitary sewer main exceeds 14 feet in depth additional easement should be dedicated in order to allow for 15 feet of either right of way or easement on either side of the sanitary sewer main. A twenty foot easement was added to provide sufficient space when combined with the remainder of the right of way for maintenance of the sanitary sewer line S -4. This sewer line was re- aligned to be in the center of this available space. . (Sheet 22) Please note use of end caps on proposed steel casing. The use of end caps has been noted. Off Please verify and place a note on the plans that no sanitary sewer service will be left more than 3.5 feet deep at the point of terminus by developer's contractor. Note #9 was added to the sanitary sewer plans concerning the depth of cleanouts at the terminus of sanitary sewer services. 31. Please verify and place note on plans that water services will be left between 2 and 3 - - • - - • - • - 110 • - •••• _ • • - veloper contractor. Also note that a ball valve is required at the point of ter us. Note #6 was added to the water line plans • : ng the depth of water line services at their terminus. 32. (Fire Flow) Please provide Water System Analysis included the oversized infrastructure as well. The Water System Analysis has been modified to include the oversized lines being proposed with this project. A revised copy is included with this submittal. . (Fire Flow) Additional hydrants are needed; there are residential lots that are greater than 500 feet from any given hydrant. Fire hydrant assembly #1 on water line W -2 was relocated to provide coverage to lots in question. . Please provide street signage detail and 1 ut, as well as block numbers tables: a. Hadleigh Ln @ Odell Ln 4300 b. Toddington Ln @ Odell Ln 4300 c. Hadleigh Ln @ Uphor Dr is 4400 d. Toddington Ln @ Uphor Dr is 4400 A street signage plan was created and added the construction documents, and it includes the necessary signage details. . Please provide your street light plan with construction documents A street light plan was created and added to the construction documents. 36. Ple- contact Frank Borroni with the United States Postal Service ank.e.borroni ; 979 - 693 -4152) to discuss mailbox locations and please provide the City with these correspondences. We have provided a copy of the proposed plat to Mr. Barroni and asked for his input on locations of mailboxes. The initial e-mail was sent March 30, 2011. Following repeated telephone calls and e- mails, we have not received any comments and are still awaiting his response. Pad locations for USPS mailboxes can be added at any point in the future so it is not imperative that they be shown on the construction drawings. . FYI — The subject tract is located within the Spring Creek Sanitary Sewer Impact Fee Area ($98.39/LUE). Noted. . YI — For future phases Victoria and Etonbury are both classified as major collectors and will require pavement design, as presented with WS Phillips Pkwy. Noted. . In addition to the following standard comments, if more than 5 acres will be disturbed during construction of this project a NOI must be filed with the state and a copy provided to the CoCS. Storm water management requirements are as follows, any questions may be directed to Donnie Willis, CoCS Drainage Inspector, at 979 - 764 -6375: Noted. Storm Water Discharges from Small Construction Activities The Texas Commission on Environmental Quality has issued a general permit for construction activities under the Texas Pollution Discharge Elimination System. The general permit (TXR150000) is for construction activities disturbing at least 1 but less than 5 acres or is part of a common plan of development disturbing at least 1 but less than 5 acres. You will need to follow these steps to discharge storm water from your construction site to the City of College Station's Municipal Separate Storm Water Sewer System (MS4): 1. Read the general permit (TXR150000) to make sure it applies to your situation. 2. Adhere to the requirements of the general permit (TXR150000). 3. Prepare and implement a Storm Water Pollution Prevention Plan in accordance with Part III of the general permit (TXR150000). 4. Sign and post a construction site notice. 5. At least 2 days before beginning construction, provide a copy of the site notice to the operator of any Municipal Separate Storm Water Sewer System (MS4) into which storm water will be discharged. A MS4s include streets, channels, gutters, ditches or anything else that is publicly owned, designed or used to collect or transport storm water. As long as you meet the conditions of this general permit, you are authorized to discharge storm water. No notice of intent (NOI), notice of termination (NOT), or fee is required under this option —as long as the requirements of this general permit are followed. This particular general permit will expire at midnight on March 5, 2013. A copy of General Permit TXR150000 can be obtained from TCEQ at: http /www.tceq.state.tx. us/ assets / public /permitting /waterquality/ attachments /stormwater /txr150000. p df A copy of the construction site notice can be obtained from TCEQ at: http /www.tceq.state.tx. us/ assets / public /permitting /waterq uality/ attachments /stormwater /txr152d2. pdf ENGINEERING COMMENTS NO. 2 (Drainage Report) . As stated in your report you are proposing to utilize the additional capacity available in "Tower downstream Tower Point" detention facility during the 2 -yr through 50 -yr storm events, while the project will be detaining for the 100 -yr event on -site. Are there any concerns related to additional erosion created from the added intensity of the more frequent and smaller storm events (2 -yr through 50 -yr storm). While it is not shown in the Drainage Report, we modeled the post- development conditions for the 2, 10, 25 & 50 yr events in our HEC -HMS model and found that the downstream peak flowrates are all reduced from pre- development conditions. Thus, we do not expect additional adverse effects from erosion caused by the flowrates in these smaller events. 2. Please provide an exhibit illustrating the study points discussed in Exhibits F & G. Study point locations have been added to the Post Development Drainage Area Map on Exhibit B. A revised copy of the Drainage Report is included with this submittal. Please confirm that none of the existing Tots /structures in Castlegate I will be affected by te r the proposed change in the 100 -yr (Blocked) water surface elevation from the Castlegate 1 — Modified Pond. The 100 -yr blocked water surface elevation for the modified pond in Castlegate 1 is 309.8 feet. This elevation contour falls within the Common Area around the existing pond. It is below the gro nd elevation of the adjoining lots. . (Sheet 2) Please confirm the proposed top of berm elevation of 310.5 adjacent to the existing section of Victoria Avenue. As indicated in #3 above, the blocked WSEL in this pond is 309.8 feet. The low point on the perimeter of the detention is 310.0 at the sidewalk and inlet on Victoria Avenue near the Camber Court intersection. This pond was not built under the current design guidelines requiring an analysis of the blocked water surface elevation, so it can be expected that the perimeter elevation would be somewhat less than current requirements would dictate. However, even under the extreme condition involving a blocked outfall, the pond will still function as desired. Modifications to the grading plan have been made near the Castlegate Drive /Victoria Avenue Intersection to increase the perimeter elevation in that location, but changes at the inlet /sidewalk location on Victoria are more difficult, and provide little or no benefit for mitigating flood damages. In the unlikely event that the WSEL in the pond exceeds the blocked conditions level, water would simply spill out into Victoria Avenue, run down the curb, and flow into the same natural drainage channel without harming any surrounding homes or property. In effect, this low poi serves as a secondary spillway if the primary spillway fails completely. . (Sheet 2) Proposed flume is labeled as sidewalk? / This label was incorrect. It now reads "6' Concrete Flume" fd. (Sheet 2) The modified outlet structure detail is on Sheet 9 not Sheet 8? ✓ ✓✓ The modified outlet structure detail is now located on sheet 11. heet 3) Could the 10 foot wide sidewalk elevation be adjusted from Sta. 22 +00 to Sta. 25 +00 to a minimum of 314.70 in order to keep the 100 -yr " Castlegate 2 — North Pond Blocked Outlet" water surface elevation from spilling into WS Phillips Parkway. It looks to be less than a 1 foot elevation change in all areas and does not appear to have any effect on the proposed design grade of the future section of WS Phillips Parkway. The sidewalk was raised in this area such that the minimum elevation is about 314.70 Sheet 10) Pipe ID for Storm Pipe #140 differs from plan and profile. The Pipe IDs now match on the plan and profile. 9. (Exhibit L — 10yr & 100yr) Please verify that your exhibit elevation match the construction document plan /profile elevations, several appear to differ. There were several pipe elevations that did not match. Additional changes were made to the storm sewer model that resulted in elevation changes to many of the storm pipes, including some not included in the questions within the City's comments. The pipe elevations shown on the construction plans now reflect what is shown in the drainage report exhibits. All pipes are sized sufficiently and have available capacity, and keep the corresponding HGLs within the elevations specified in the Drainage Design Guidelines. 10. (Exhibit L — 10yr) Please revise Rim Elevation Upstream for Pipe ID #230. See response #9. 11. (Exhibit L — 10 yr) The HGL appears to exceed the Rim Elevation downstream for Pipe ID #232. After making revisions to our storm sewer model, all HGLs stay below the rim elevations for the 10 year storm event. In addition, the HGL does not exceed the R.O. W. elevation in the 100 year storm event. 12. (Exhibit L — 10yr) Please confirm total flow and available capacity data provided for Pipe ID #140. See response #9. 13. (Exhibit L — 100 yr) Pipe ID #160, please check HGL downstream data. See response #9. 14. (Exhibit L — 100 yr) Pipe ID #150, please check Total Flow data. See response #9. 15. (Exhibit L — 100 yr) Pipe ID #140, please check Capacity data. See response #9. 16. (Exhibit L — 100 yr) Please check HGL and Rim Elevation upstream and downstream data for Pipe ID #211, 212, 213, 220, 221, 230, 231 & 232. See response #9. 17. (Exhibit L — 100yr) In the areas where the HGL is exceeding the Rim Elevation is the water surface elevation staying within the right of way? It appears that some of the proposed HGL encroach into your proposed residential Tots. See response #9. 1 . During a 100 -yr event Pond 1 will back up into Pond 2 and Pond 2 will back up into the proposed storm sewer system; did you perform a backwater analysis using the tailwater conditions to verify the system will function properly once the system is inundated by the subject storm event? The wording in this comment is not clear. The storm drain system for this subdivision is designed to convey stormwater from a 10 yr event. During a 100 yr event, the entire system will cease to `function properly" and water will be flowing overland. The storm drain system has been modeled assuming a tail water effect at the outfall in the 100 yr event, and the HGL's remain inside of the right -of -way lines as required. . During the 100 -yr event "blocked outlet condition" there appears to be very little future buildable area available on Block 7, Lot 1, A -O tract, please address. According to the Drainage Report, the WSEL under blocked conditions will be 314.7 feet. The Final Plat calls for a minimum finished floor elevation of 316.0, which means that fill will be imported as needed to build on this lot. Since much of the lot falls outside of the FEMA floodplain limits as delineated in the Spring Creek LOMR, it can be raised as much as desired by the owners. . Based on the height of the outlet structures proposed and being modified, please verify that these structures do not fall under the TCEQ Dam Safety Program regulations (TCEQ Chapter 299). According to the TCEQ Dam Safety Laws, the definition of a dam is "any barrier, including one for flood detention, designed to impound liquid volumes and which has a height of dam greater than six feet. This does not include highway, railroad or other roadway embankments, including low water crossing that may temporarily detain floodwater, levees designed to prevent inundation by floodwater, closed dikes designed to temporarily impound liquids in the event of emergencies, or off - channel impoundments authorized by the commission in accordance with Texas Water Code, Chapter 26, or the Texas Solid Waste Disposal Act, Texas Civil Statutes Article 4477-7." In our case, the embankment of WS Phillips Parkway is less than 6 feet when measured from the flow line of channel to the low point on the street (5.57 feet). Due to its height and the fact that it is a road embankment, it does not fall under the TCEQ definition of a dam. The outlet structure serving the existing Castlegate pond measures only 4 feet from the top of berm to the flow line of the outlet. It too, is built up as part of the roadway embankment for Castlegate Drive and thus does not qualify as a dam. RESPONSE TO ENGINEERING COMMENTS NO. 2 . Please submit bonding documents related to the City Participation Agreement. The bonding documents are included with this submittal. e ' .. PI =:se pay outstanding development permit fee of $11,930.41 //��' - outstanding fee will be paid when we pick up the approved plans and Development Permit. ,cr ease sign and return easement dedication documents as soon as you receive them, this must b e accomplished before CSU Electric can pull wire. At the time of this submittal, the easement dedication documents are still being processed by the COCS Legal Department. They will be signed and returned as soon as they are received. 4. P ase provide documentation and certification concerning permitting through the United States Corp of Engineers. A copy of the Pre - Construction Notification was included with the previous submittal. Since that time, we have attempted to contact the USACE for their input but have been unsuccessful in reaching them yet. A note has been added to the plans stating that no work shall be undertaken in or around the existing channel or the small wetland area identified in the report. The documentation and certification will be forwarded as soon as it is received. 5 . Please provide correspondence with the pipeline company. A copy of the e -mail correspondence is included with this submittal. It merely states that they have received our plans and will review them soon. At the time of this submittal, no comments have been received. Sheet 4) Victoria mis- labeled as 48' B -B. The labeled was changed to 38'B -B. . Please place a note on the plans that the developer's contractor will terminate water services with a ball valve. A label was added to the water line p /ans stating, "The contractor shall terminate the water services with a ball valve." . Please provide street signage detail and layout, as well as block numbers tables: a. Please add W S Phillips Pkwy © Victoria Ave 4200 blk b. Please add Odell Ln @ W S Phillips Pkwy 4400 blk The block number table was updated. The detail provided to us by the City is included in the plans. . Please provide most recent modifications based on the United States Postal Service comments. The location and specs of the LISPS mailbox pad has been added on Sheet 4. \