Robert Armijo, City Engineer From: Jim Nelson Subject
Total Page:16
File Type:pdf, Size:1020Kb
TECHNICAL MEMORANDUM (FINAL VERSION) Date: October 8, 2019 To: Robert Armijo, City Engineer From: Jim Nelson Subject: Supplement No. 3 to Citywide Storm Drainage Master Plan Lammers and Mountain House Watersheds SWC File: 2014-96CC This Technical Memorandum and its supporting exhibits and tables present Supplement No. 3 to the Citywide Storm Drainage Master Plan (SDMP) that was adopted by the Tracy City Council on April 16, 2013 by Resolution No. 2013-056. This supplement has been prepared to revise and update components of the storm drainage infrastructure plan for the Lammers and Mountain House Watersheds in the City’s Sphere of Influence. The primary reasons for preparing this Supplement No. 3 to the Citywide SDMP at this time include the following: • The alignment of selected segments of the Lammers Outfall Storm Drain system is proposed to be altered. Alterations will include a northerly shift of some storm drain segments to follow the south side of Eleventh Street to more efficiently follow existing topography and allow certain storm drain and sanitary sewer trunk lines to align parallel and contiguous to each other to improve efficiency of construction and maintenance. • Extensive development has occurred in this area since the current Citywide SDMP was adopted, and an update is needed to allow for official adoption of minor changes in Sub-basin boundaries and Supplement No. 3 to Citywide Storm Drainage Master Plan (FINAL VERSION) Lammers and Mountain House Watersheds To: Robert Armijo, City Engineer October 8, 2019 Page 2 detention basin sizes and locations associated with proposed storm drainage infrastructure. • The revisions herein may improve opportunities to accelerate the construction of the Lammers Outfall Storm Drain System, facilitating the conversion of several existing temporary retention basins serving existing development to detention basins having a positive drainage outflow. Proposed revisions and updates to the Citywide SDMP presented herein have been supported by additional hydrologic and hydraulic calculations, additional investigation of physical conditions and input from City staff. Exhibit A is a portion of Figure 5-1A from the Citywide SDMP that depicts the existing adopted storm drainage plan for the broader portion of the City where changes and updates are being proposed with this Supplement No. 3. The area to be served includes Cordes Ranch, various International Park of Commerce existing and proposed development areas, the property formerly known as the Gateway property, and other properties in the area. Proposed updates to program storm drainage infrastructure and minor adjustments to Sub-basins and Watershed boundaries proposed per this Supplement No. 3 to the Citywide SDMP are depicted and listed on Exhibit B and include the following: • Changes to the alignment of selected segments of the Lammers Outfall Storm Drain system. • Minor Sub-basin changes (L17A/L17B, transfer 22 acres of the Mountain House Watershed into the Lammers Watershed, L20/L14). • DET MWH3a/3b/3c storage volume is reduced from 37 acre- feet (AF) to 33 AF due to a 22 acre reduction in the contributing drainage area per the watershed adjustment cited above. Supplement No. 3 to Citywide Storm Drainage Master Plan (FINAL VERSION) Lammers and Mountain House Watersheds To: Robert Armijo, City Engineer October 8, 2019 Page 3 • DET LW6 storage volume is increased from 101 AF to 103 AF due to minor sub-basin changes (L20/L14). • DET LW9a storage volume is increased from 89 AF to 94 AF due to minor sub-basin changes (L17A/L17B) and watershed adjustments. • DET LW8 is no longer depicted as a linear basin. • DET LW10A, LW10B, LW9a and LW6 have minor location or configuration changes. • DET LW3 is shown as an aggregate basin not located as of yet and will become three (3) or so smaller basins to be determined by the Specific Plan process for the property formerly known as Gateway. • DET LW4 and LW5 will drain to the existing Lammers Road street storm drain system and/or future onsite storm drainage facilities serving the property formerly known as Gateway that will be directed to DET LW3; DET LW4 and LW5 (1 cfs outflow, total) will be “pass through” drainage in DET LW3 and will not affect the DET LW3 storage volume. Also, the following statement contained at the top of page 5.22 in the Citywide SDMP relevant to new development within the Mountain House Watershed is proposed to be changed from: New development within the Mountain House Watershed will not be allowed by the City prior to the execution of said agreement. (“Said agreement” refers to a future drainage agreement with Mountain House CSD). to: New development within the Mountain House Watershed will not be allowed to discharge to downstream facilities operated by the Mountain House CSD Supplement No. 3 to Citywide Storm Drainage Master Plan (FINAL VERSION) Lammers and Mountain House Watersheds To: Robert Armijo, City Engineer October 8, 2019 Page 4 unless an agreement that authorizes said discharge is executed between the City and the Mountain House CSD. Supplement No. 3 does not alter the following relevant components of the Citywide SDMP as it pertains to the subject area: • The 2010 Drainage Agreement Between the City of Tracy and The West Side Irrigation District • Outflow rates from detention basins proposed to serve this area (except for a DET LW3 outflow increase from 4 cfs to 5 cfs for “pass through” of storm water already stored and detained in DET LW4 and LW5). This Supplement No. 3 to the Citywide Storm Drainage Master Plan also includes updated Opinions of Probable Cost (OPCs) for program storm drainage infrastructure that will serve the Lammers and Mountain House Watersheds. Separate OPCs have been prepared each watershed. These OPCs will be incorporated into an updated impact fee analysis performed by Harris & Associates for these watersheds. Exhibits: Exhibit A – Portion of Figure 5-1A from Existing Citywide Storm Drainage Master Plan Showing Existing and Proposed Storm Drainage Facilities in the City’s Lammers and Mountain House Watersheds Exhibit B – Proposed Revisions to the Existing Citywide Storm Drainage Master Plan per Supplement No. 3 Tables: Table 1 – Opinion of Probable Cost for Program Storm Drainage Infrastructure, Supplement No. 3 to the Citywide SDMP (Lammers Watershed) Table 2 – Opinion of Probable Cost for Program Storm Drainage Infrastructure, Supplement No. 3 to the Citywide SDMP (Mountain House Watershed) Supplement No. 3 to Citywide Storm Drainage Master Plan (FINAL VERSION) Lammers and Mountain House Watersheds To: Robert Armijo, City Engineer October 8, 2019 Page 5 Cc: Andrew Malik, City of Tracy Bill Dean, City of Tracy Al Gali, City of Tracy Ilene Macintire, City of Tracy Nanda Gottiparthy, SNG Associates Mike O’Connor, SNG Associates Alison Bouley, Harris & Associates Sarah McIlroy, Stantec RA 4 8 u EXPANSION DET LW1 WSID SUB M ILR 48" SD o ! W87 ! 4 Scale: 2 48" SD " M 1” = 1,500’ OAD S (if printed full size at 11”x17”) AIN DR W94 ! Von Sosten Rd FILIOS! 4 AIN 2-76"X48" HEPs 42" SD * L23 2-60" SDs 2- CATELLUS 60" SD W 60" s WSID LOWER MAIN CANA IR D! R S " BERG/BYRON8 4 4 2- d 8" 60 S " S DET LW2 D Ds D S ! R D " S ! 6 " 3 !24 0 " 3 B S D n D ! S D ^_ D S S 0" " D " 3 e 2 - 10' x 10' CBCs 4 4 S 2 30 2 " S 29" x 18" CMPA " * s 6 DET MHW3cV 3 DET MHW3b18" SDFM * 36" x 22" CMPA L22 L BERG/B * n = * 2 - 6' x 3' CBC W86 30" RCP 36" x 22" CMPA BRIGHT D a S * MH3 DET LW8 " 36" RCPD Culvert * Eleventh St 4 DET MHW3a 2 H V 12" SD D 54 2 - 5' x 5' CBCs ! ! L18 30" SD 48" SD V DELTA MENDOTA CANAL L19 W83 ! D D S ! DET LW7 1 " 2" 2 12" SD ! 24" SD ! SD 4 " SD F RUN 30" SD 18 M 36" RCP Culvert DET MHW2 36 ! " * DET LW9b = SD V L24 DET LW4 W84 GATEWAY D S L17B DET LW3 L20 " MH1 DET LW9a D 0 S 3 WSID UPPER MAIN CANAL " 6 3 PATTERSON L21A CORDES RANCH DET * LW6 V 12" SDFM ! 93" RCP Culvert MH2 DET = W L17A 30" SD LW5 D L14 ! L21 W82 L08 Exhibit A – Portion of Figure 5-1AL21 from Existing Citywide Storm Drainage Master Plan ShowingWESTSID ED 3.5' x 3.5' CBC S Existing and Proposed Storm Drainage Facilities in " * 0 RESIDENTIA3 DET LW10b V the City’sL08 Lammers and Mountaind House Watersheds D L16B DET LW10a S " Supplement No. 3 to the R Citywide SDMP 8 *# 1 L07 Legend from Figure 5-1A: 36" Pipe Overchute L16A s ( Existing Storm Drain r ( ProposedW80 Pump Stations 36" Pipe Overchute Proposed Storm Drain e Subbasins *# 12" SD Existing Detention L15c Watershed Boundaries2 L15d 4" m S DET LW11 Proposed Detention Sphere of Influence D OFF1 DET L15a L13 D WEST 6" S cy_nei_exhibit_A_supplement_3.ai mlm 1-28-2019 DET L15b 3 ! Pipe Change " Existing Channel ! 2 m 1 *# SIDE Overchutes Proposed GreenbeltChannel Parkway Parkway D a D * Culverts V L12 100-yrProposed Floodplain Greenbelt Parkway 78" RCP Culvert INDUSTRIAL * Proposed Culverts L 10' x 4' Overchute D DrainProposed Inlet Opento Channel C L15b L15a D L05 ^_ OutfallsL06 Delta Mendota Canal A *# L10 100W45 Fl d l i N P D= DATE: May 2019 O SWC PROJECT NO. 2014-96CC DET LW12 L11 D UNI 45' Bridge 2 - 36" CMPs 3 - 36" HDPEs 10' x 8' Overchute * *V V:\1840\active\184010206\northeast_industrial_area\graphics\tra *# V D 7.5' x 3.5' *VOverchute 4 - 6' x 3' CBCs *# *# D L04 RA 4 8 u EXPANSION DET LW1 WSID SUB M ILR 48" SD o ! W87 ! 4 Scale: 2 48"SD " M 1” = 1,500’ OAD S (if printed full size at 11”x17”) A IN W94 ! Von Sosten Rd D FILIOS! R 4 AIN 2-76"X48" HEPs 42" SD * L23 2-60" SDs 2- CATELLUS 60" S 6 D W 0" s WSID LOWER MAIN CANA IR D! R S " d BERG/BYRON8 4 4 2- R 60 8" " SD SDs DET LW2 D S D! n " ! 6 S " 3 24 0 e ! " 3 B S D D s ! S D ^_ D S S 0" " D " 3 n 2 - 10' x 10' CBCs 4 4 S 2 30 2 " S " * 29" x 18" CMPA a 6 DET MHW3cV 3 DET MHW3b L 18" * * 36" x 22" CMPA H L22 BERG/B SDFM = * 2 - 6' x 3' CBC W86 30" RCP 36" x 22" CMPA BRIGHT D S * MH3 " 36" RCPD Culvert * Eleventh St 4 DET MHW3a 2 DET LW8 V 12" SD 36” SD D 54 2 - 5' x 5' CBCs ! ! ! L18 30” SD 30" SD 48" SD V L19 W83 ! D D S 30” SD DET LW7 DET LW3 2 1 1 " 2" 2 12" SD ! 24" SD ! 24” SD SD 4 ! F RUN M 36" RCP Culvert DET MHW2 DET 36 ! " DELTA MENDOTA* CANAL LW9b = SD V L17B L24 GATEWAY DET LW4 W84 DET L20 24” SD MH1 LW9a D ! S " 6 3 PATTERSON WSID UPPERDET MAIN CANAL L21A CORDES RANCH LW6 * 1 V 18” SD 12" SDFM ! Supplement No.