Municipality of Anchorage, Alaska Parks & Recreation Department

Transcription

1 Municipality of Anchorage, Alaska Parks & ecreation Department 632 W. 6 th Avenue, Suite 630 P.O. Box Anchorage, AK Tel UL MEMOANDUM Date: May 3, 2017 To: Cc: From: Parks & ecreation Commission Josh Durand, Parks Superintendent Tom Korosei, Park Planner PC Campbell Creek Park Alterations Local oad ehab. & Project: Drainage Improvements, PM&E Projects #14-28 & #14-37 POJECT OVEVIEW The Parks and ecreation Commission is requested to approve proposed installation of a storm water infiltration system and related equipment in part of the Campbell Creek Greenbelt located on the north side of Campbell Creek, at the intersection of Folker Street and E. 46 th Ave. The site is northwest of the central, active area of Campbell Creek Park. The project is part of storm water drainage improvements to an area adjacent to the park, an area that the Parks and ecreation Department understands has longstanding experience with flooding of neighborhood streets. The MOA Public Works Dept. has developed plans to address drainage deficiencies in the area in conjunction with certain roadway improvements. Earlier recommendations to direct the storm water to the Tudor oad drainage system were objected to by Alaska Dept. of Transportation and Public Facilities. As a result a system directing the water to nearby Campbell Creek was chosen. The infiltration system is expected to help protect the water quality of Campbell Creek and reduce erosion by intercepting storm water runoff rather than direct discharge to the creek, meeting qualification as low impact development. The affected park parcel is dedicated park land, and records indicate that the parcel may have been acquired in part with a grant from the Land and Water Conservation Fund of the National Park Service. Most of the installation in the park would be underground at a site where a tennis court was removed in 2011 and is now open turf. The main part of the system is a series of chambers to collect runoff and allow the water to percolate into the subgrade. At ground level would be three manholes and a driveway for maintenance of the facility. Parks and ecreation staff believes that the driveway surface should be a porous pavement system to allow turf to grow while supporting maintenance vehicles. A porous pavement system would minimize the visual impact and allow continued recreational use of the surface. Overflow from the infiltration system would flow through a culvert approx. 83 feet to Campbell Creek. Additional information about the project is attached.

2 PC PM&E oad & Drainage Improvements, Proj. Nos & May 3, 2017 Page 2 of 2 The project, in particular the infiltration system proposed for installation in the park, was presented to the Campbell Park Community Council at its meeting April 20, Attendees at that meeting expressed general support for the project and no objection to the proposed use of the park area. The project engineer indicates that landscaping and parking would be possible over the system, but not permanent structures or roadways. The Parks and ecreation Department staff believes that current recreational use of this area would not be unreasonably diminished, provided the proposed driveway and other above-ground components are designed to minimize visibility and protrusion and the area is adequately restored after construction. STAFF ECOMMENDATION The Parks and ecreation Department requests that the Parks and ecreation Commission approve the attached resolution regarding the proposed construction of storm water drainage facilities in a portion of the Campbell Creek Greenbelt generally as described. The Parks and ecreation Dept. expects to execute an intragovernmental use permit for the project to address general mitigation and compensation concerns. Cc: Eric Hohman, PTS, Inc. PAKS & ECEATION DEPATMENT Municipality of Anchorage, Alaska

3 Municipality of Anchorage, Alaska Parks & ecreation Commission 632 W. 6 th Avenue, Suite 630 P.O. Box Anchorage, AK esolution No equest for Approval of Proposed Drainage Facility Installation in Campbell Creek Park (Greenbelt) WHEEAS, the Anchorage Parks and ecreation Commission serves in an advisory capacity to both the Mayor and the Assembly; and WHEEAS, the Anchorage Parks and ecreation Commission has the responsibility and duty to provide for the long term vision of our park system by ensuring that a balance of parks, natural resources, and recreation facilities provides for the health, welfare, and safety of all residents of the Anchorage Bowl; and WHEEAS, Campbell Creek Park and greenbelt area are popular neighborhood park areas, dedicated in 1984; and WHEEAS, Campbell Creek Park provides open play areas and also provides buffer area for Campbell Creek and adjoining neighborhood; and WHEEAS, the Project Management & Engineering determined that certain facilities including storm water infiltration system are needed to address drainage deficiencies to better serve the community in the vicinity of Campbell Creek and meet applicable design standards; and WHEEAS, installation of the infiltration system on the subject park land facilitates accomplishing the objectives of the proposed improvements, including minimizing potential adverse effects of storm water discharge; and WHEEAS, the Campbell Park Community Council at its meeting April 20, 2017, has reviewed and is generally in support of the proposed plans; and WHEEAS, the Parks and ecreation Department understands that with certain design features such as porous paving system, and upon execution of an intragovernmental use permit, the facility would not cause significant loss of usefulness or visual quality to the park; now, therefore, BE IT ESOLVED, that the Anchorage Parks and ecreation Commission supports in principle the proposed installation of drainage facilities in Campbell Creek Park greenbelt land generally as proposed, incorporating features to minimize visual obtrusiveness such as Geoblock type of porous paving material for maintenance access, and execution of an intragovernmental use permit. PASSED AND APPOVED by the Anchorage Parks and ecreation Commission this 11th day of May, ATTEST: Chair Parks and ecreation Commission John H. odda, Director Parks & ecreation Department

4 Lake Otis Parkway Folker Street Folker Street Campbell Park Loop Laurel Street Infiltration system-- approx. proposed location Lot 6, Eden Park Subd. Addn. 1 Plat No East 46th Avenue Campbell Creek Park Campbell Creek East 48th Avenue ² Campbell Creek Greenbelt Feet Park Property portion

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9 8'-1" [2464mm] CONNECTING PVC INFLOW PIPE TM TM CONNECTING PIPE TM INFLOW PIPE INSTALLATION OF STOMCHAMBE SYSTEMS (can be downloaded and printed from TENCH PEPAATION DOWNFLOW END UPFLOW END 1. Do not excavate trench until dry weather is forecast long enough to allow at least coverage of the StormChamber system with filter fabric prior to raining. STOMCHAMBE EXAMPLE CONFIGUATION 2. Excavate to a width and length sufficient to accommodate the number of StormChambers plus a minimum one foot border around the entire bed. The OPTIONAL IMPEVIOUS LINE bottom of the bed must be level, unless otherwise specified. STOMCHAMBE ALONG TENCH WALLS AND HEAVY WEIGHT BOTTOM MAY BE EQUIED 3. Do not use heavy equipment on the excavated trench bed in order to avoid soil compaction. OPTIONAL UNDE DAIN NETTING (SUPPLIED) OPTIONAL 12" (300mm) PVC ISE FO SOME DETENTION POJECTS 4. If use of heavy equipment on the excavated trench bed can not be avoided, scarify the trench bottom and break up soil clumps and till smooth before PIPE FO IN FLOW WITH GATED adding the stone base. 8'-7" [2617mm] MANHOLE COVE ASSEMBLY 5. Line trench walls with a 4-ounce [113g] non-woven filter fabric such as Mirafi 140N or 140NC, Synthetic Industries 401, or AMOCCO 4545 or STAT CHAMBE CONFIGUATION Overlap adjacent filter fabric by at least 2' [600mm]. Do not place filter fabric under the StormChambers. STAT MODEL IS CLOSED AT THE SIDE POTAL END AND PATIALLY OPEN AT THE TOP POTAL END 6. Unless otherwise specified, place 6" [150mm] of crushed, washed, 3/4" - 2" [20mm - 50mm] hard, non-calcarious stone on the bottom of the trench. The base must be level and at a zero grade. 7. If it becomes impractical to level the stone base by hand, use a low pressure, tracked dozer, not exceeding 1,100 lbs/sf [500kg/sf], maintaining at least 6" [150mm] of stone under the tracks at all times. PEFEED STOMCHAMBE STOMCHAMBE INSTALLATION OUT FALL LOCATION HEAVY WEIGHT 1. You may need assistance in separating the StormChambers. Based on weather and transit conditions, sometimes the StormChambers become tightly NETTING (SUPPLIED) compacted. Separate StormChambers using two 2 x 4 studs along one side of the stack for leverage. Do not use any damaged units - contact UNDE IN FLOW AND 8'-2" [2490mm] ADJACENT STAT UNIT(S) StormChamber immediately. 2. Start building the StormChamber system with the Start Unit StormChambers at the inflow end of the StormChamber system. The Start Units are MIDDLE CHAMBE CONFIGUATION 9" [230mm] MINIMUM 10" (250mm) PVC BETWEEN completely closed at the end with the two side portals. MIDDLE MODEL IS COMPLETELY OPEN AT THE SIDE POTAL END AND PATIALLY OPEN AT THE TOP POTAL END SEPAATION IN FLOW AND ADJACENT STAT 3. oll out two rows of StormChamber light weight stabilization netting (provided with the StormChambers) perpendicular to the rows of where the Start BETWEEN UNIT(S) AS "EMEGENCY OWS SPILLWAY" Unit StormChambers will be placed. Overlap the rows by approximately 1' [300mm]. Keep the netting flat; if moved, straighten and flatten out. CATCH BASIN WITH 4. Place one piece of the StormChamber heavy weight stabilization netting (provided with the StormChambers) under each StormChamber that will be 3' - 4' (900mm - 1,200mm) receiving inlet storm drain pipes. Cut a hole in the netting to fit snuggly around the exposed top of the SedimenTrap. Place on top of the light weight netting SUMP AND SNOUT and extend beyond all edges of the StormChamber. The purpose of heavy weight stabilization netting is to function as a "splash pan", preventing excavation of the underlying stone and soil, while allowing infiltration to occur. 10" [250mm] PVC CLEAN OUT ISE 5. Place the Start Unit StormChambers (completely closed at the end with the two side portals), spaced a minimum of 5' 9" [1753mm] apart at the center 8'-2" [2490mm] AND UNDE-LYING SEDIMENTAP line of the end walls (9" [230mm] apart at the base). Position the closed ends at least 1' [300mm] from the trench wall. END CHAMBE CONFIGUATION 6. Cut open the side portals for the inflow storm drain pipes (size and location specified on the plans) and lateral connecting pipes between StormChamber END MODEL IS COMPLETELY OPEN AT THE SIDE POTAL END AND COMPLETLY CLOSED AT THE TOP POTAL END Start Units (8" [200mm] or 10" [250mm] Schedule 40 or SD 35 PVC; 8" [200mm] or 10" [250mm] HDPE will not fit) with a reciprocating saw, router bit on a drill, or keyhole saw along the defines indented circle. 10" [250mm] PVC pipe is the largest diameter pipe that can fit into the side portals. If the inflow END CHAMBE STAT CHAMBE PEFEED IN FLOW storm drain pipe is specified to enter the closed end wall, place a piece of the pipe against the end wall. Trace the diameter of the pipe on the end wall and LOCATION UP TO cut out the circle. The maximum pipe size that can be inserted into the end wall is 30" [750mm] O.D. 30" [750mm] O.D. PIPE 10" [250mm] PVC CLEAN OUT 7. If a cut extends more than 0.5" [13mm] beyond the intended diameter, place a piece of the StormChamber non-woven filter fabric over the hole, cut an ISE AND UNDE-LYING "X" just short of the width of the opening, and insert the pipe. ALTENATIVE IN FLOW LOCATION SEDIMENTAP 8. Mark the midpoints of 8" [200mm] or 10" [250mm] PVC pipe and insert into the adjacent StormChamber Start Units where specified so that the marked FO LAGE THAN 10" [250mm] PIPE, UP TO 30" [750mm] O.D. midpoint is centered between the two adjacent StormChambers. Pipe length should be sufficient to extend 6" [150mm] - 12" [300mm] into both adjacent ALTENATE IN FLOW LOCATION FO 10" [250mm] PVC PIPE (TYPICAL), O StormChambers (about 4' [1200mm]). In order to facilitate placement, install the lateral connecting pipes in the specified StormChambers before attaching SMALLE the next StormChambers in the row. LIGHT WEIGHT STABILIZATION 9. If the locations of row - connecting PVC pipes are not specified, add 8" [200mm] or 10" [250mm] PVC pipes to connect all the Start Unit StormChambers NETTING (SUPPLIED) UNDE IN FLOW AND ADJACENT OW(S) of each row. 8'-1" [2464mm] 7'-7" [2311mm] CATCH BASIN WITH 10. oll out additional StormChamber light weight stabilization netting, over-laying the previous sheet by 1' [300mm] and place the first rib of a Middle Unit 3' - 4' (900mm - 1,200mm) LAY-UP LENGTHS (completely open at side portal end partially open at top portal end) over the last rib of each of the Start Unit StormChambers. SUMP AND SNOUT 11. Screw the StormChambers together at their base on both sides with regular 3" [75mm] dry wall screws. One screw on each side is sufficient to NOTE: 1. Start chambers (closed at the side portal end) are placed at the inflow end of the rows. temporarily hold the StormChambers together until the stone is place. The gap between the two StormChambers near their base must be closed enough to 2. Begin placements with Start chambers and end rows with End chambers. TM prevent stone from migrating into them to prevent potential surface subsidence. 3. Place first rib of next chamber in the row over last rib of previous chamber. STOMCHAMBE WITH SEDIMENTAP 12. Continue placing and screwing the rest of the StormChambers, one at a time, leaving at least 1' [300mm] between the end of the End Unit (completely CAST ION FAME WITH COVE open at the side portal end, completely closed at the top portal end) and the trench wall. 95% COMPACTED CLEAN FILL O 3' X 3' [900mm x 900mm] 3/4" - 2" [20mm - 50mm] CUSHED WASHED STONE 13. For large StormChamber systems it is advisable to install and backfill a few StormChambers of all rows at a time as you continue to install the rest of INSPECTION COVE EINFOCED the chambers. CONCETE PAD PAVEMENT 14. Deposit 3/4" - 2" [20mm - 50mm] crushed, washed, hard stone directly along the centerline of the StormChambers to evenly flow down each side to O AS SPECIFIED keep the StormChambers in proper alignment. DO NOT use limestone. Limestone gets pasty when wet and will tend to reduce the void spaces in the 8" [200mm] 8'-6" [2591mm] stone. Do not place the stone directly against the closed end walls at the start and end of the rows. Add stone to 6" [150mm] above the StormChambers, 7' [2130mm] 1'-6" [457mm] 18" [450mm] MIN unless otherwise specified. 10" [250mm] PVC PIPE 15. Level the stone cover with a vibratory compactor, not to exceed a dynamic force of 10,000 pounds [4536kg], or with a low pressure, tracked vehicle not ISE SCH40 O DL35 6" [150mm] MIN exceeding 1,100 lbs/sf [500kg/sf]. IMPOTANT: If a low pressure, tracked dozer is used, do not run the dozer on anything less than 6" [150mm] of stone above the StormChambers. Spread 5'-0" [1524mm] 3/4" - 2" [20mm - 50mm] LIGHTWEIGHT STABILIZATION CUSHED, WASHED, stone is small piles to prevent movement of the StormChambers. Caution must be exercised when placing stone on top of the StormChambers so that NETTING (SUPPLIED) UNDE IN FLOW 4'-8" [1422mm] STONE AND ADJACENT STOMCHAMBE excessive pressure is not applied directly on the StormChambers by equipment "buckets". OW(S) 16 Cover the stone with StormChamber non-woven filter fabric. Overlap adjacent sheets by at least 2' [600mm]. 6" [150mm] MIN BACKFILLING END UNIT 1. Backfill soil must be free from large stones and large organic material (e.g. tree limbs and root stumps), and is capable of being compacted to at least CUTOUT GUIDE FO 10" [250mm], 90% of the Standard Proctor Test (AASHTO Method T-99). If not, crusher run or other suitable backfill material must be used. The stone surrounding the AND 12" [300mm] PVC ISE PIPE StormChambers can also be extended up to the pavement subgrade, if desired. STOMCHAMBE 20" [508mm] 24" [610mm] SEDIMENTAP 2. Compaction of the soil backfill must be achieved in 6" [150mm] - 8" [200mm] lifts. Grading of lifts should start in one corner of the system with a low pressure, tracked dozer, with a pressure not exceeding 1,100 lbs/sf [500kg/sf], keeping at least 1' [300mm] of fill in front of the blade at all times. Compact 47" [1194mm] STAT UNIT lifts to 90% Standard Proctor with tracked vehicles not exceeding 1,100 lbs/sf [500kg/sf], or with a hand operated compactor or vibratory roller not CUT OUT GUIDE FO 10" [250mm] exceeding a dynamic force of 20,000 lbs [9071kg]. PVC PIPE O SMALLE 3. Keep the StormChamber system closed or protected from receiving sediment until the site is completely stabilized (grass growing and all pavement placed). 1'-11" [584mm] 1'-1" [330mm] 2'-10" [864mm] 10" [250mm] PVC PIPE ISE, SCH 40 O DL35, WITH ABOUT 12" [300mm] LONG PIPE INSETED 10" [250mm] PVC PIPE ISE, SCH 40 O DL35 WITH COUPLING, WITH ABOUT 12" [300mm] LONG PIPE INSETED IMPOTANT: After compaction of backfill and setting of final grade, avoid parking on or traversing over the StormChamber installation with heavily loaded trucks and heavy equipment until paved. IMPOTANT: These instructions assume accepted construction procedures and trucks that do not exceed specified DOT load limits. Uncustomary loads or improper load distributions in vehicles may require additional cover. Contact StormChamber for installation under abnormal conditions. Installations not in compliance with these instructions will void warranty. 95% COMPACTED CLEAN FILL O 3/4" - 2" [20mm - 50mm] CUSHED WASHED STONE 3/4" - 2" [20mm - 50mm] CUSHED WASHED STONE OPTIONAL UNDE DAIN STOMCHAMBE TYPICAL COSS-SECTION INSTALLATION (POVIDED AS AN ILLUSTATED EXAMPLE ONLY) FO PAVED AEAS PAVEMENT PAVEMENT BASE LIGHT WEIGHT STABILIZATION NETTING (SUPPLIED) UNDE IN FLOW AND ADJACENT OW(S) 10" [250mm] PVC FO UNPAVED AEAS 4 OZ. [113g] NON-WOVEN FILTE FABIC AT STONE/SOIL INTEFACE 6" [150mm] MIN PEFEED IN FLOW LOCATION (UP TO 30" [750mm] O.D. PIPE) ALTENATIVE CONFIGUATION 95% COMPACTED, CLEAN FILL O CONTINUE CUSHED WASHED STONE TO SUFACE 18" [450mm] MIN ALTENATE SIDE POTAL IN FLOW OPTION (10" [250mm] PVC) 4 OZ. [113g] NON-WOVEN FILTE FABIC AGAINST TENCH WALL AND TOP OF STONE 6.7' x 10' [2000mm x 3050mm] HEAVYWEIGHT STABILIZATION NETTING (SUPPLIED) UNDE IN FLOW AND ADJACENT STAT UNIT(S) 95% COMPACTED CLEAN FILL O 3/4" - 2" [20mm - 50mm] CUSHED WASHED STONE 3/4" - 2" [20mm - 50mm] CUSHED WASHED STONE 6" [150mm] MIN 12" [300mm] ECOMMENDED STACKED INSTALLATION OF STOMCHAMBE FO STOMWATE MANAGEMENT (POVIDED AS AN ILLUSTATED EXAMPLE ONLY) FO PAVED AEAS PAVEMENT PAVEMENT BASE PEFEED IN FLOW LOCATION (UP TO 30" [750mm] O.D. PIPE) FO UNPAVED AEAS 4 OZ. [113g] NON-WOVEN FILTE FABIC AT STONE/SOIL INTEFACE 10" [250mm] PVC 95% COMPACTED, CLEAN FILL O CONTINUE CUSHED WASHED STONE TO SUFACE 6" [150mm] MIN 18" [450mm] MIN SIDE POTAL IN FLOW OPTION (10" [250mm] PVC) 12" [300mm] MIN 6.7' x 10' [2000mm x 3050mm] HEAVYWEIGHT STABILIZATION NETTING (SUPPLIED) UNDE IN FLOW AND ADJACENT STAT UNIT(S) LIGHT WEIGHT STABILIZATION NETTING (SUPPLIED) UNDE INFLOW AND ADJACENT OW(S) PODUCT ENGINEEING SPECIFICATIONS FO STOMCHAMBE Each chamber will be formed from high molecular weight/high density polyethylene. Each chamber will be composed of at least 40% recycled material. The stone base that the chambers are placed on will not be compacted in order to avoid compaction of the stone-soil interface, which restricts soil infiltration. The chamber system will be designed without filter fabric under the chambers in order to avoid restriction of soil infiltration, which occurs from the normal clogging of the filter fabric from sediment and debris deposition. Use of filter fabric between the soil and stone backfill layer and lining the side walls of the excavated area will be required to prevent intrusion of soil or silt into the chambers and surrounding stone. Each chamber will be capable of supporting a minimum of 24,000 pounds [10,886kg] per square foot (i.e., three times the AASHTO H-20 Wheel Load ating). Each chamber will be capable of being installed with a minimum of 25 feet [7620mm] of cover above the crown of the chamber. Each chamber system will be capable of being installed in at least two layers, providing a minimum of 0.8 cubic feet of storage per square foot of surface area. Each chamber system will be capable of being installed with a minimum of six inches [150mm] of stone base. Each chamber will be 34.04" [864mm] high, 60" [1524mm] wide and 102.5" [2591mm] long. Lay-up length will be 8.1' [2464mm] (start and end unit) and 7.6' [2311mm] (middle unit). Each chamber will have 14 ribs of approximately 3.6" [91.4mm] in height, 3.8" [96.5mm] wide at the top and tapering to 4.4" [112mm] at the bottom. Spacing of the ribs at the bottom of the chamber will be approximately 4.9" [124mm] and approximately 3.2" [81.3mm] at the top. One smaller rib sized dimensionally to effectively nest under and interlock to connect units will be 2.9" [73.7mm] high, 3.3" [83.8] wide at the top of the rib, and 4.1" [104mm] wide at the base. Overall height to the inside rib will be 30.44" [864.62mm]. Overall height to the outside rib will be 34.04" [773.18mm]. Each chamber will have a defined top portal which is structurally enhanced to compensate for loss of structural integrity when apertures are cut open to receive pipe. Each such portal will be capable to receive up to a 12" [300mm] PVC pipe. Each chamber will have defined side portals on opposing sides which are structurally enhanced to compensate for loss of structural integrity when apertures are cut open to receive pipe. Invert height for a 10" [250mm] PVC pipe through a defined side portal will be 17.49" [444.25mm]. Invert height for an 8" [200mm] PVC pipe through a defined side portal will be 18.49" [469.65mm]. Each chamber will be capable to accept an 8" [200mm] or 10" [250mm] PVC feed pipe through a defined side portal. Each chamber will be capable to accept up to a 30" [750mm] OD pipe through its end wall. Each chamber will be capable of storing at least 9 cubic feet per lineal foot with 6" [150mm] or stone above and below the chamber. Each chamber system will be designed without utilizing a header pipe manifold system. Stone diameter will be 3/4" - 2" [20mm - 50mm]. STOMCHAMBE DESIGN DETAILS SHEET For Availibility and Pricing Please Call: Storm hamber TOLL FEE: DAWING EVISION Info@StormChambers.com NOT TO SCALE DAWINGS

10 POJECT MANAGEMENT & ENGINEEING DEPATMENT OWNE'S INITIALS: PAGE OF DATED SENATE DISTICT H LOCAL D. EHABILITATION & DAINAGE IMPOV. PM&E # & EXISTING PACEL AEA: ± 36,847 S.F. OW ACQUISITION TYPE: DE OW ACQUISITION AEA: ± 7,859 S.F. SCALE: 1"=60' DATE: GID: SW1834 PACEL No. 1A

11 POJECT MANAGEMENT & ENGINEEING DEPATMENT OWNE'S INITIALS: PAGE OF DATED SENATE DISTICT H LOCAL D. EHABILITATION & DAINAGE IMPOV. PM&E # & EXISTING PACEL AEA: ± 36,847 S.F. OW ACQUISITION TYPE: ITCP OW ACQUISITION AEA: ± 12,272 S.F. SCALE: GID: 1"=60' DATE: SW1834 PACEL No. 1