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HomeMy WebLinkAbout2001-10-09 BRAA Email to OPHKris Danielson From: Sent: To: Cc: Subject: Postler, Dennis M [dpostler a@bonestroo.com] Tuesday, October 09, 2001 5:08 PM Kris Danielson (E -mail) Scott Richards (E-mail); Kimberly Kamper (E- mail); Jay Johnson (E- mail); Jim Butler (E- mail); Hanson, David D Oak Park Station Kris: As a follow -up to the letter faxed to you earlier today, we have finished our analysis of the existing pond in the Kern Center under ultimate development conditions assuming the 12" outlet restriction remains in place. Under this scenario, the pond surface area needs to be increased by 3.0 acres from its current surface area of 2.5 acres (as you may recall in the letter the existing pond surface needs to be increased by 1.0 acres if the 12" outlet restriction is removed). Just a reminder that this is for the Kern Center completely developed. The area the existing pond needs to be enlarged due to Oak Park Station will be some incremental portion of the 3.0 acres listed above (probably a fairly large portion since Oak Park Station is the largest piece of undeveloped land remaining in the Kern Center), and METRO Land Surveying & Engineering is determining that number - which we will review. Thanks. Dennis M. Postler Bonestroo, Rosene, Anderlik & Associates 2335 West Highway 36, St. Paul, MN 55113 Direct: (651) 604 -4815 Office: (651) 636 -4600, x4815 Fax: (651) 636 -1311 Cellular: (612) 865 -9187 E -mail: dpostler©bonestroo.com BONESTROO AND ASSOC 17:, 6516361311 Conversation Record By: Erik Peters Project blame: Oak Park Station Spoke with: Doug Utterer Title: Organization: Metro Land Surveying and Engineering Ponding requirements Subject: 2onestrao, Rosen°, Ander and Associates 2335 Highway 35 West Hi hwa 36 1 St. Paul, MN 5511311 Phone: 651-636-460011 Fax: 651 -636 -1311 10/09/01 13 :06 :08/08 NO :905 Date: Oct, 3, 2001 Project No: 55 -Gen Phone Number: 651-766-0112 Boriestroo Rosene mar Associates Enor 1 (i & Arch Itect1 Doug Pond Sizing for Flood Control: 1 clarified for Dou a few issues regarding pond design for flood control. 1. The � existin HWL cannot increase to maintain existing discharge rates. Additional flood storage �w► volume w ill need to be provided. The most cost effective means for the developer to provide the flood storages to expand existing is and the existin Kerns Center Pond. Expanding the Kerns Center Pond is p also what we e as the city want to see. Centralizing the ponding allows full utilization of the added Y storage volume. The city also needs to have the pond expanded (see item 3). 1 directed him to expand the Kerns Center Pond. 2. The preliminary estimate of additional flood storage volume is the runoff volume difference between existing conditions and fully developed ed conditions, 1 told him that we assumed existing conditions to be weedy, grass field with a CN of 66. He would need to estimate future build -out conditions. Once we receive a grading plan with the expansion to the Kerns Pond we can determine if the discharge e g p ex p rate will be maintained. 3. The desired HWL for Kerns Pond is 934, however the existing HWL is 935' +. The desired HWL is based on estimated d low floor elevations from adjacent properties. Today's higher HWL leaves less freeboard for flood protection, 1 told him that ultimately the city needs the Kerns Center Pond to have a minimum surface area of 3.5 acres at the NWL and 23.5 acre -feet of flood storage between (9286') the NWL and HWL of 934. The pond currently has a surface area of 2.5 acres. Pond Sizing for Water Quality: 1, For water quality the wet storage is governed by two issues a. Desired average depth of 4 feet (minimum average depth of 3 feet). with quality b. Review wit the water uallt model (PondNET) to restrict pollutant (phosphorus) discharge to 200 ppb outflow concentration. 2. Since this is a pond expansion and not an individual pond, use of PondNET is a little difficult for the developer to quantify given `v n the additional offsite drainage area Hence l told him to meet item #la q and provide wet storage volume equal to NURP (runoff from 2.5 -inch rainfall event). Providing the NURP RP volume will like] be comparable with the city's water quality standard. K,155\55GEN\wordlGerre uoodericeioMP_EGP"GvnverG.tion with Doug Littier.dOC BONESTROO AND ASSOC Bonestroo Rosene NEM Anderlik & Associates Engineers 6. Architects October 9, 2001 Ms. Kris Danielson Community Development Director City of Oak Park Heights 14168 Oak Park Blvd., P. 0. Box 2007 Oak Park Heights, MN 55082-2007 1 2' 6516361311 10/09/01 13:06 E5] :05/08 N0:905 uonestroo. Rexene, Anderllk and Associates, Inc. is an Aft : Action /Equal Opportunity Employer and Employee Owned Principals; Ouo U. finny. rtroo. f .l". Mirvin L. Sctf vii €n, P. • Glom R. Cook, PC. • Robert G, S(r unict t, P . Jerry A, BouraOOn, IMP Senior Consultants; Rrzaert W. Rosen(. PF. d Inirpn C. Anerenik, F. o Rills, rd C. Tut Fief, RC • Sucira M. COarlin, C.P.A. Associate Principals: Ketch A. Gordon, PE. • Robert k. Proticrlc, PF a Rich:srd W. Fivarr, P.E. • D:svid 0. f.oAkotii, P.C. • Mirk A. 1 l,r1 rt, P.C. • Michael T. RAutnflann, P.E. • Ted K. FICId, Ir>~ Kt'nnrth R Anderson, I?f . • Murk R, ROlf +., P.C. • David A. Bonestroo, M.b.A. • 51dney P. WIlllamsop. F'h•, i S Ar nrx M. Ring, M.B.A. e All.fra I ?i�.k S�Iimrcl�, RE. • Trioma5 W Peterson. f',F. • James R Ma €��nn, I�.1". • Miir' H. k neon, P.E. n l.. Phillip Gravel 111, T'C. fl Daniel . Edgerton, RE. • Ismael Martinez, P. A Tnomas A, Syfko, P.F. She,!1<l r' I. ,lohns.ort • P]nIr. A. rrr,vr:, PC. • Thomas A. Roushar, P,E. Robert J. Devery. P.E. Offices: Si. Paul, Sl. Cloud, Rocht:stor and WiHni r, MN o Milwnt kce, WI a Chicasjo: IL 11 iebsite: www.I>onestroa.COm Re: Oak Park Station Preliminary Plat & Concept Development Plan Review Bonestroo File No. 55-01-000 Dear Kris: We have reviewed the preliminary plat and concept development plans for the proposed Oak Station development 4 t in the Kern Center as submitted by METRO Land Surveying & � Engineering and have the following comments /recommendations: Sitgla yout /A cces J ocations: 1 • The p ro osed plat creates a private street that loops from Memorial Avenue North . to � �th P p ` s sewer and water main arc Street North. Sanitary se proposed within the private street primarily p • nt to State Highway to serve the four lots adjacent g Y 5. Sanitary sewer and water services for the three lots adjacent ent to Memorial Avenue North are in place from previous Kern Center improvements. 2. The City may want re t to consider requiring the proposed internal street to be a public street �. � The utilities within ' i this street should be "public" since connecting to public utilities in Memorial Avenue Mort � a private Having rivate street over public utilities may result in disputes e should the utilities ities ever need repair, or maintenance and upkeep of or unclarities in the futur sh p the street itself be questioned. Requiring `oned. Re uiri the street to be public would ensure that the street � constructed to City and associated utilities are cons y standards, and the issue of ownership and /or . As such, the street should b e constructed to . standard City maintenance would be clear. 0 right-of-way, and to the appropriate tonnage classification for widths for curb and gutter and � � y: p commercial /industri al areas. San ewer:_ sanitary sewer layout o ut in the proposed internal street is acceptable as 1 The preliminary sanitary se er y P P submitted. it is assumed that three lots adjacent to Memorial Avenue North will utilize c�SS�ii'Y]cd ihdt the hr ' • ' 6 • services provided b the existing sanitary sewer sei S p y previ Kern Center improvements, if not, these services will need to be properly abandoned. 2335 West Highway 36 St. Paul, MN 55113. 651- 636-46OO ® Fax: 651 -63& -1311 BONESTROO AND ASSOC 6516361 311 10/09/01 13:06 5 :06/08 NO :905 Water Main: 6" through the site, A � water main is proposed to loop r connecting to two existing services off Memorial Avenue N. provided by previous revious Kern Center improvements. Sewer and water f different locations aloe services were provided �.t lour d� g Memorial Avenue North to serve this site. With the new plat configuration, water services now need to reach the four lots o � The developer/engineer should verify that a 6" main line will provide proposed along S.H. 5. Th pressures fire protection volumes and ressures for the new lot layouts. A better looping scenario is for the proposed water main in the internal street to connect to the main lines in Memorial Avenue N. and in 58 Street North. However, this will require cutting across both streets to make connections (via wet taps). S. The 6 " services provided along ' • v` al Memorial Avenue N. should be utilized for the three adjacent � lots, otherwise properly abandoned if not to be used a h lves and drants need to be reviewed with Publics Works and the 6. Proposed locations of y y Fire Department. rradin xaina elStorm Sewer: ed site does not change Grading for the proposed e ultimate drainage patterns tributary to the � existing Kern Center pond. The existing .i Kern Center pond has a 42" diameter outlet pipe restricted to a 12" opening. With this restriction, the pond is at maximum capacity currently y' existing for the development currentl existin in the Kern Center. The proposed grading and w enlarging the existing Kent Center pond (in outlot A). However, from drainage plan sha s � � � discussions with METRO, pond the additional and storage accounts only for the difference between a 65% impervious impervious r�pery ' ious site and an 80% im site, not for the increase in runoff from existing conditions to post-development conditions. METRO needs to calculate how on much additional ponding required ondin i s re uired due to their development with the 12" outlet restriction v` e for this additional storage in place, and pro (increase the Kern Center pond accordingly)�d g p 8 . We have analyzed the entire Kem Center as is relates to the existing pond storage and water levels under ultimate developed conditions: • With the pond ou t (opened u p to its 42" diameter pipe size), the pond 1 et unrestricted area needs to be increased 1.0 acres to accommodate ultimate development surface ax by within the ent ire Kern Center (see attached Conversation Record between Erik. Peters of our office ffice and Doug Litterer of METRO Land Surveying and Engineering). g • We are currently calculating how much the existing pond surface area needs to be increased to accommodate ultimate development within the entire Kern Center with the 12 outlet restriction remainin g in place. Assuming the 12" outlet restriction will remain in place indefinitely (Le. regional improvements to the wetland west of the Kern Center by Brown's Creek Watershed District not occurring any time soon), Oak Park Station will he and to handle their proposed l l need to enlarge osed development, as mentioned in 7. t pond P p above, at a minimum. n • Once we have the entire Kern Center modeled under ultimate development conditions with the 1 2" outlet restriction place, ion in lace , we can deterrn in e how much larger the existing • dlor how much ponding will need to be, an p g is required for those portions of the Kern Center currently undeveloped. physically develo ed. If possible, enlarging the existing pond is more desirable, both economically hydraulically, and draulically, than each development. providing its own Y on -site ponding. BONESTROO AND ASSOC • 6516361311 10/09/01 13 :06 L 1 :07/08 NO :905 the internal street to handle all internal storm water runoff 9. Two catch basins are proposed on . area ma should be submitted to verify the proposed Drainage calculations and a drainage map . storm water flows and/or whether more storm sewer is needed. storm sewer can handle s y district (Valley l0 The a roprtate watershed des Branch) should be contacted by the appropriate for com liance with any requirements they may have p Basements � � l , Existing drainage and utility easements along existing lot lines within Oak Park Station will I l g � ew drainage e and utility t. need to be vacated and n � �' easements established as part of this plat If you have any questions regarding uestions rc ardin this review, please contact me at (651) 604 -4815. Sincerely, BONESTROO ROSENE, ANDERLIK & ASSOCIATES INC 4,40 Dennis M. Postler, P.B. cc: Scott Richards Northwest Associated Consultants, Inc. Kim Kamper, Acting City Administrator Jay Johnson, Public Works Director Jim Butler, Building Official DMP, DDII, File Bonestroo K:\55\O1d \Oak Park Statioit • Pre). Plat &Cu;lcept ))cv. Plat1sa14- '1- O1,doc