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RESPONSE TO ENG COMMENTS RND 2.pdfI I engineering p c FNIM"TTMT Date: November 14, 2014 To: Site Workshop 222 Etruria St, Suite 200 Seattle, WA 98109 Attn: Brian Bishop From: Steve Hatzenbeler, PE Project: Edmonds Spray Park LPD Project No: 028-14-01 Subject: City of Edmonds Plait Review Comments Response 911 Western Avenue, Suite 420 Seattle, WA 98104 p. 206.725.1211 f. 206.973.5344 1pdengineering.com The following is response to the City of Edmonds review comments dated October 7, 2014. Please let us know if you have any questions or additional concerns. We greatly appreciate all of your coordination with us to quickly move this through the permitting process. Page 1 of 7 Engineering Cornments LPD Response 1. Please address the following call out issues to provide clarity to the plans and assist with clearer referencing during the construction process: a) SID #07 connects to an existing catch basin to the northwest, 1a) The callout has been relocated closer to the that existing catch basin then connects to a second existing catch basin. catch basin to the west. The callouts for the second catch basin are located on the west side of the asphalt road, quite a way away from the actual catch basin. The leader is the same weight as the other pipe lines. Please revise to avoid confusion. b) Assign identifiers to the existing catch basins. 1b) Catch basin identifiers have been added to ........ .. ... existing catch basins 2. Please revisit rim elevation for SID 407. If 5 ft between invert and SDtf7 rim elevation has been revised to 28.50. The rim then a type 2 catch basin should installed. The grade lines as distance from rim to IE is 4.5 ft, so the Type I CB shown on the plan indicate that the rim may be closer to 28. appears to be acceptable. Please make revisions as needed. 3. The second existing catch basin referenced in comment "la" has Existing drainage pipes connected to the CB will a length of pipe directed to the north and another length not be altered. It is not known with certainty directed northwest that do not connect to anything. Will they be where the two rioted pipes connect; they are abandoned? Do they connect somewhere that is not shown? Also included in the survey and expected to remain as. - the cb callout has two NW inverts; which is the pipe that extends is. Pipes that connect to the existing CB will rernain to the far west existing cb? ------------- -- unless they are proven not to be needed during . . ....... Page 1 of 7 engineerinNgo November 14, 2014 Edmonds Spray Park City of Edmonds Public Works Department - Engineering Division Plan Review Comments Page 2 of 7 Engineering Comments LPC Response 1. Sewer Lift Station - No data/calculations/report/sizing/pump construction. We assume the lower IE is the pipe curves has been provided for the sewer lift station for the project that extends to the far west existing CB. 4. The existing catch basin located just a bit to the southwest of The note has been amended as requested. SDCO #6 is noted to be filled with dirt. Please add to the note Appendix B of the drainage report. "Clean out catch basin...." the phrase "replace with new type 1 Datum. Pipe connection inverts to tank have been catch basin if damaged". added to sheets C2.0 and C3.0 as applicable. Utility Engineer Comments — Project`Calculations Reviewer: Michele (Mike) F. De Ulla, P.E., LEEP AP LPD Response 1. Sewer Lift Station - No data/calculations/report/sizing/pump The sewer lift station pump curves showing the curves has been provided for the sewer lift station for the project analysis of the performance of the two 2 -HP site. The consultant was asked to follow Engineering Handout E61 pumps are included with the resubmittal in for the design of the pump station, so there is no way for us to Appendix B of the drainage report. check sizing, type of pump, buoyancy calcs, etc. (as detailed in the Datum. Pipe connection inverts to tank have been handout). As discussed in the meeting, modifications to the added to sheets C2.0 and C3.0 as applicable. flow/storage rates would be allowed to account for the fact that this is just draining the spray ground. 2. Buoyancy for storage tank — It is understood that the tank will Buoyancy analysis has been added as section 5.7 have an underdrain system. The geotechnical report (HWA of the drainage report. The approximate elevation 9/18/2014), however, recommends that that the design of flood water in the parking lot was previously groundwater level for buoyancy purposes should be one foot considered in the design of the detention system, above the existing ground surface. Verify that the designer and the approximate elevation and related believes that the proposed underdrain system and associated information have been added to the Downstream concrete anchor are sufficient in these artisan groundwater Analysis section of the drainage report. conditions to prevent the detention pipe from floating without additional ballast. Underdrains can fail due to clogging. Also based on previous meeting comments by Rich Lindsey, during the winter, portions of the park parking lot are subject to flooding due to the rain events and the proximity of the nearby marsh. Has the consultant determined this flood stage water level to verify that the drainage system could still function and keep the empty tank from floating up? Or worse yet having the underdrain system act as a conduit for the flood waters to go in? Utility Engineer Comments: Plans Reviewer: Michele (Mike) F. De Lill, P.E., LEEP AP LPC Response 1. Sheets C2.0 & M4.00 Provide grades so that tank inverts/connection points are known. The project survey, included as reference with the Detail 2 on M4.00 has dimensions from top of grade, but site is project permit documents is based upon NAVD88 sloped. At least one NAVD88 reference grade needs to be and all elevations shown are on the NAVD 88 supplied. Also detail 2 on M4.00 shows a step between finish Datum. Pipe connection inverts to tank have been grade and the concrete collar, but detail 3 shows it flush. What is added to sheets C2.0 and C3.0 as applicable. the depth of the slab, thickness, etc. so that contractor knows November 14,20I4 Edmonds Spray Park City ofEdmonds Public Works Dopartment- Engineering Division Plan Review Comments Page 3 of Utility Engineer Comments: Plans LPD Response Reviewer: Michele (Mike) F. De 1-1111a, P.E., LEEP AP how much concrete to pour, with what dimensions, how to tie it in and what straps are made of? engineerinMgI November 14, 2014 Edmonds Spray Park City of Edmonds Public Works Department - Engineering Division Plan Review Comments Page 4of7 Utility Engineer Comments: Plans LPD Response Reviewer: Michele (Mike) F. De Lily, P.E., LEEP AP 2. Sheet C3.0 a) Water service piping shown as PE, plain PE is not allowed. City 2a) The pipe material has been revised to standard is copper. Municipex crosslinked PE pipe with indicate Municipex crosslinked PE pipe and associated 14 gauge PVC coated copper locator wire is the the depth and alignment information have only other alternative. Also depth and alignment information been added to sheet C3.0. The location where needs to be supplied so that it can be as -built properly. the water service enters the building has Location of where water service enters the building does not been modified to match the current match mechanical dwg on M2.00. Location on mech plans is mechanical drawings. better since you will not need to cross all the water supply lines to the spray park. Coordinate with mechanical and realign. b) Sewer FM profile missing. Horizontal alignment information 2b) A sanitary sewer force main profile has been missing as well. Also bends are shown in the FM pipe. These added to sheet C4.4 (new sheet), and called need to be sweeps/arcs. Verify that HDPE has a 200 psi rating. out on C3.0. Approximate horizontal alignment information has been added to the plan. The bends have been revised to sweeps. The pipe has been revised to 200 psi High - Mol PE per the City standards. 3. Sheet C3.1 a) Sewer FM profile missing. Horizontal alignment information 3a) A sanitary sewer force main profile has been missing as well. Also bends are shown in the FM pipe. These added to sheet C4.4 (new sheet), and called need to be sweeps/arcs. Verify that HDPE has a 200 psi rating. out on C3.1. Approximate horizontal alignment information has been added to the plan. The bends have been revised to sweeps. The pipe has been revised to 200 psi High - Mol PE per the City standards. b) Based on orientation of lid for the new manhole being placed 3b) The manhole orientation and location have in the ROW, an interior drop into the MH structure cannot be been changed. The IE in and out have also built as detailed, since the invert penetration for the FM will been modified to provide adequate cover at be somewhere between the cone transition or the riser. The the point of connection to the manhole. MH opening will need to be rotated 180 degrees to have the drop detail work as shown. Also at best, the FM at MH connection has about 1.1' of cover at connection, but lift station detail shows 2' cover min. Recommend rotating the manhole 180 degrees and also shifting it 3 feet east of the current location so that the lid is at the back of sidewalk and the cone portion is facing the roadway. This should solve the cover issue and the inside drop issue. c) SS service lateral connection shall be per COE std detail E6.4. 3c) The SS service lateral connection has been called out per COE Std Det E6.4, and the detail has been added to sheet C4.4 (new sheet). 4. Sheet C4.3 Pump Detail — a) 1 hp pumps shown. Standard per E61 is 2hp. Please revise so 4a) Pumps have been revised to 2 HP. that it matches all our other lift stations. Ops staff does not want to have even more materials on hand for maintenance. engineerinNgo November 14, 2014 Edmonds Spray Park City of Edmonds Public Works Department - Engineering Division Plan Review Comments Page 5 of 7 Utility Engineer Comments: Plans LPD Response Reviewer: Michele (Mike) F. De Lina, P.E., LEEP AP b) How are the valve extension handles for the gate valve 4b) The gate valves have been moved outside the secured so that they don't drop in the structure? Why were manhole. The detail has been modified to they not placed outside? (Was it because of all the supply include all the standard items in accordance pipes leading to the spray park?) Gate valves need to be non with COE Std Det E6.8. rising stem. Also, what is the pipe in the structure made out of and also how long is the piece of pipe after the gate valve? Can valve extensions be made so that they operate at such angles in relation to the lid? Also, verify clearances for all valves (gate/check valves) so that there is actually enough space in the structure to perform maintenance/access on the structure and valves so that there is adequate space and clearances can be removed for maintenance. A to scale x,y,z dimension check of this needs to be done. c) What is the purpose of the pump encasement pipe? From 4c) The pump encasement pipe has been previous meetings, there should not be any debris. What is it eliminated. The pumps are mounted on rails made out of? How is it secured? How many holes are needed that keep them above the bottom of the and what distance on center and how many rows? How many sump. holes are needed so that performance of pump is not affected? d) Pump needs to be on rail system per E61. 4d) The pumps are mounted on rails in accordance with E61 and COE Std Det E6.8. e) Provide Buoyancy calcs, since no underdrain system has been 4e) Buoyancy analysis has been included in provided. Add ballast as needed. Section 5.7 of the drainage report. f) Is lid of structure a MH lid? If so, please specify. Larger 4f) The City requested a larger diameter opening opening would be better, especially if the gate valves are to for the manhole, so we have increased it to a stay in the structure. 30 -inch opening. We have specified a hinged 4'x4' access hatch rather than a manhole cover, and a detail for the installation has been added. g) Where is the vent pipe? 4g) A 3 -inch PVC air vent pipe has been added to the SS lift station detail. h) 3" HDPE is shown with 2' min depth. Please show minimum 4h) On Detail 2/C4.4, a dimension has been clearance of HDPE in relation to the soffit of the structure, added to identify the minimum clearance of 1 because as shown, the HDPE could literally be at the soffit of ft below the bottom of the manhole top slab. the structure (making maintenance difficult) and still make The specified HDPE (Driscoplex 4100) has a the 2' minimum burial depth. HDPE needs to have a 200 psi rating of 250 psi. rating. I) All pipe penetrations shall have Calpico link seals with the 4i) On Detail 2/C4.4, a note regarding the tightening bolts installed so that they can be tightened from inclusion of Calpico link seals has been added the inside of the structure. to the detail. Storm Drain Cleanout j) Provide locking lid and revise to reference COE std E6.2. 4j) COE Std Det E6.2 has been added to the drawings, Detail 1/sheet C4.3. engineerinNgl November 14, 2014 Edmonds Spray Park City of Edmonds Public Works Department - Engineering Division Plan Review Comments Page 6 of 7 Utility Engineer Comments: dans Reviewer: Michele (Mike) F. De Lilla, P.E., ;LEEP AP LPC Response 5. Sheet M1.01 Material type for all piping not shown. Please supply so that city can verify that city standard materials are being used. Buoyancy analysis has been added as section 5.7 of 6. Sheet M2.00 the drainage report. The approximate elevation of All cleanouts need to have locking lids and be per COE std. E6.2. flood water in the parking lot was previously Stormwater Engineer Comments — Stormwater Site Plan LPC Response Reviewer: Jerry Shuster, P.E. 1. Buoyancy It is understood that the detention system has an underdrain Buoyancy analysis has been added as section 5.7 of system. The geotechnical report (HWA 9/18/2014), however, the drainage report. The approximate elevation of recommends that that the design groundwater level for flood water in the parking lot was previously buoyancy purposes should be one foot above the existing ground considered in the design of the detention system, surface. Verify that the designer believes that the proposed and the approximate elevation and related underdrain system is sufficient in these artesian groundwater information have been added to the Downstream conditions to prevent the detention pipe from floating without Analysis section of the drainage report. additional ballast. Underdrains can fail due to clogging. In addition, anecdotal information for Park's employees indicate that during large storm events the western part of the park's parking lot is flooded meaning the proposed underdrain system may not have anywhere to drain or be backwatered. 2. Section 5.4, page 7 a) The text states that 1,275 SF of impervious area (0.029 acres) 2a) The bypass basin has been renamed and a was modeled as bypass. The WWHM4 report in Appendix B screenshot of the model schematic has been does not have this basin (Basin 2) as a bypass basin. Please included in the WWHM model output in reconcile and show a screenshot of the WWHM schematic Appendix B of the drainage report. showing the basins with the accompanying basin areas and the detention pipe icon with the appropriate mode input information. b) The allowable release rates from the Edmonds Stormwater 2b) WWHM model has been revised to include Code Supplement listed in Table 2 are correct. These values, 0.027 acres of lawn tributary to the detention however, assume all disturbed pervious areas on a site have system. Results of the model showed no compost -amended soils so these area essentially generate significant changes in release rates for all zero runoff. This is not the case here where the wood chip three -recurrence intervals; therefore the play area is assumed to be 50 percent impervious and 50 detention design is unchanged. The report percent pervious (assume lawn). The model should include and exhibits have been revised to clarify the 0.027 acres of lawn for sizing the detention system. impervious and pervious areas, and bypass area. 3. Appendix B, WWHM4 Report Why is orifice 1 at an elevation of 0.5 ft? 0.5 ft of dead storage is noted in figure 3.14 of volume III of the 2005 Department Of Ecology Stormwater Management Manual For Western Washington. The bottom 0.5 ft of the pipe will be used for dead storage. IMM engineering pllc 911 Western Avenue, Suite 420 Seattle, WA 98104 p. 206.725.1211 f. 206.973.5344 Ipdengineering.com Stormwater Engineer Comments — project Drawings LRD Response Reviewer: Jerry Shuster, P.E. 1. Sheet C4.3 — Notes and Details a) Replace the City of Bellevue reference in the "Detention Pipe 1a) The notes have been revised to eliminate Structural Notes" with the City of Edmonds. notes that are not needed, and references to the City of Bellevue have been deleted. b) Detail 8 references the City of Edmonds drawing No, E5.4. 1b) Detail E5.4 has been added to Sheet C4.3 of Add this detail drawing to the plan set; an AutoCAD version is the plan set. available on our website. Public Works Comments LPD Response 1. Install RPBA at water meter, and hot box. Install RPBA or Airgap The water meter, RPBA, and water service line to at water tank. the southern edge of the spraypark project site will be installed by the Parks Department and are not a part of this project. cc: File Page 7 of 7