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Home My WebLink AboutConceptual Mitigation Plan - PLN General - 3/30/2003 THE COOT COMPANY Wetland and Wildlife Consulting Services 416 S. Washington Olympia,WA 98501 (360)352-9897 FAX(360)352-9914 CONCEPTUAL MITIGATION PLAN FOR THE ALDE"ROOK/SR-106 RELOCATION S33T22NR3W Mason County MARCH 2O03 prepared for: Barbara Anderson Woerman Collins 777 108th Avenue NE, Ste 400 Bellevue WA 98004 0�of th'etla, prepared by: e�� IO SYJS i S. Shanewise, PWS rt ',003 9 Senior Ecologist ��t��i^1 4 Sa`� l LV6iIcS�•�� A .a ►� CONTENTS Introduction............................................................................I Roadcut Mitigation Difficult..................................................l Unsuitable Wetland Creation Conditions..............................1 Mixed Mitigation Proposed...................................................I Wetland/Stream Function Preservation.................................2 Mature Riparian Forest Preservation.....................................2 Full, Functional Mitigation Compensation............................2 Exhibit 1: Proposed Mitigation Plan Exhibit 2: Proposed Wetland Mitigation Terraces — Cross Section J Introduction This conceptual mitigation plan has been prepared for the Alderbrook Resort Project environmental impacts to streams,wetlands and ESA species. An initial mitigation concept to provide some compensation by creating wetlands at the toe of the roadcut habitat was rejected because of threats to roadway integrity. In addition, creating wetlands elsewhere in the vicinity landscape would harm sensitive steep slopes and valuable mature forest habitat. Hence,preservation techniques are offered instead that will keep primary onsite wetland and stream functions as well as permanently preserve a large acreage of mature forested habitat along Alderbrook Creek that can protect expansion habitat for ESA species. Roadcut Mitigation Difficult Creating wetlands within benched areas along the new roadcut where the existing wetlands occur has problems. WSDOT representatives and project engineers are concerned about secondary, long-term saturation of the roadbed from wetland hydrology needs. In addition,the benched area available for wetland creation would not meet a minimum 1:1 mitigation ratio, and expanding the roadcut to create more space for compensation wetlands just increases the area of project impacts to wetlands. Unsuitable Wetland Creation Conditions All terrain within the general vicinity of this project is unsuitable for wetland creation. The landscape here consists of steep slopes that rise abruptly from the shoreline of hood Canal or dry,perched, well-drained flats that lack hydrology sources. Nearly all areas are thickly wooded with dense, mature conifer forest. Trying to force a new wetland into such conditions may actually produce more functional harm than good from the cumulative impacts of tree cutting and earthwork. Indeed, forested habitats, especially slopes, are a key element for protecting the Hood Canal watershed, and should not be sacrificed to mitigate wetland impacts without severe cause and justification. Mixed Mitigation Proposed The proposed mitigation approach incorporates a combination of preservation techniques. First, the existing primary wetland hydrologic functions will be preserved on-site by maintaining and enhancing existing ground and surface water flows. Second, adjacent, upstream mature forested habitat along Alderbrook Creek will be permanently preserved within a land conservation easement. These aspects are discussed individually below. Alderbrook Conceptual Mitigation Plan The Coot Company 1 Wetland/Stream Function Preservation Preservation of existing wetland and stream functions in the impact areas will be achieved with two techniques. Areas along the roadcut slope where groundwater surface saturation occurs will be cut with narrow terraces. This will slow runoff rates and cause the water to percolate into soils better. Such groundwater recharge may benefit Hood Canal by increasing freshwater shoreline aquifer inputs in summertime. In addition to the terracing, all terminal slope seepage and stream flows will be kept separate from the to Hood Canal surface waters along highway stormwater, and directed g the same outfall Sh routes they currently drain through. The combination of these actions will maintain, if not enhance, existing ground and surface water flow connections to Hood Canal within the project area. Mature Riparian Forest Preservation The second method of mitigation involves easement preservation of 30 acres of mature forest habitat along the shorelines of Alderbrook Creek. This habitat will provide both excellent protection for the restored salmon runs in the creek, and good recovery habitat for marbled murrelets and bald eagles. The 100+year old trees here have better potential for munrelet nesting than specimens within project impact areas, and will provide at least equal opportunity for bald eagle nesting and roosting. In addition,protection of the steep slopes surrounding the creek from any machinery disturbances caused by logging or development will prevent soil erosion and help maintain high quality stream conditions for fish Full, Functional Mitigation Compensation The proposed preservation of habitat function and habitat area presented within this mitigation plan will fully compensate for project impacts to the Type 5 streams,wetlands and ESA species. Habitat function will be preserved because all existing, impacted wetland and stream areas will still persist within the cut slope established by the new roadway. Indeed,the area of technical wetland conditions may well remain unchanged across the face of the new slope because the existing groundwater discharge will continue to occur. In addition,the 30 acre forested area slated for preservation will provide better murrelet and eagle habitat than occurs within project impact areas(see Washington Forestry Consultants, Inc. report dated Mar. 7,2003)while simultaneously protecting the stream quality for restored fish runs in Alderbrook Creek. Suffice to say the mitigation proposed is both adequate and good. Alderbrook Conceptual Mitigation Plan The Coot Company 2 r HOOD ►T CANAL 'ALRfER60 4M 4 r ADDITIONAL 150'BUFFER + FOR WETLAND MITIGATION • 5.4 ACRES ,Y wuw j r 30 ACRES OF THE EAST i r- PARCEL AREA TO BE DEDICATED AS A : PERMANENT CONS EASEMENT LNG • ALDERBROO REEK '�� 1•e ,, ' '� ADDITIONAL � FER r { FOR ROAD CONSTRUCTION r ,_• • • M > �Q''' MITIGATIO,%.4.3 ACRES ., b TOTAL EAST A WEST Y , `�. + }•� i ` �,' PARCELS AREA = 85.9 ACRES • �+� w ,'l �L.rf 7 � ,v 4• f� �J,�+i.:,E7'f' i N'. '',• •w •, fir .-1Mf i •a ' �� j � i i i -26 i. �yEXHIBIT NO 1 •yf,� ALDERBOOK RESORT REMODEL y� r cn W W ry W Ir (!) CD F- U CDQ Q [If Of (!) F- W Z ~ J U Q Z a- O 1 60 FEET 45 OF HILLSIDE 2: 1 SLOPE TO ROADWAY RIGHT OF WAY TERRACES TOP OF CUT CROSS SECTION OF ROADWAY CUT TERRACES EXHIBIT NO. 2 SCALE: 1"=20' ROADWAY TERRACES M -Top view side view NOTES: SUMMARY ON/OFF SITE IMPACT stale divider fox widh>10 R 1.2'DEEP DITCH TO COLLECT HILLSIDE RUNOFF or.pi",of n.e s"owa Wa"gUaIRY des+gn depth m�4' 2.ROADSIDE DITCH TO COLLECT RUNOFF FROM THE HILLSIDE CUT(ONLY). 1. ROOFS = 1.51 ACRES T`"`" 1A. CONCRETE CULVERT AREA FOR PROPOSED ACTION �Yrl" /f(2"far kegtently mowed areas) 3.BROOKHAVEN DRAINAGE(TYPE 5 DRAINAGE) 2. OFFSITE ROADS = 2.31 ACRES. 4.STORM WATER OUTFLOW TO EXISTING DISCHARGE POINT CLEAN RUNOFF , LANDSCAPED°eoy�a O a%9 b C„e:,4r '---- ---/--- 5.STORM WATER COLLECTION DITCH FOR HILLSIDE RUNOFF(CLEAN RUNOFF) 4. PARKING AR &ACCESS =C 344 ACRES 2.23 ACRES „, r 6. 120'LONG Bio-SWALE TO TREAT ROADWAY RUNOFF S. OFFSITE RD SLOPES = 4.57 ACRES �_2'cam dl[x1 into 7.EXISTING STORM WATER OUTFALL-TREATED STORM WATER DISPOSAL 6.STREAMS&RIPARIAN = 0.9 ACRES TrIlch bq[gn vAdlh_(b) 6•nam sw B.240'OF BIO-SWALE TO TREAT PARKING LOT DRAINAGE C O.recrly�wta % R.—wil le '-� 9. COURTYARD STORM WATER FILTRATION/TREATMENT SYSTEM tl P a`"n`°Fa a I 10.BUILDING ROOF DRAINS AND FOUND.DRAINS-CLEAN WATER TOTAL IMPACT AREA = 15.10 ACRES u o bo e.. Gan ow-�}dwber ` 11.GRAVEL OVER SAND PARKING LOT-INFILTRATION/TREATMENT i S.—0— Sand Rdta 12.SR 106 TO BE CURBED-RUNOFF FLOWS WEST INTO INFILTRATION SYSTEM Swv a.r"s°.een 13. WEST PARKING LOT STORM WATER COLLECTION SYSTEM 14'STORM WATER INFILTRATION SYSTEM-SR 106, WEST LOT&FIRE LANE TYPICAL BIO SWALE SECTION A.ALDERBROOK CREEK-95'LONG X 12'WIDE BOTTOMLESS CULVERT B.REALIGN ALDERBROOK CREEK TO ACHIEVE A 4%STREAM GRADE&FLOODPLAIN. C.ALDERBROOK CREEK-RETAIN OLD STREAM CHANNEL&CONSTRUCT REARING POND. D.ALDERBROOK CREEK-34'WIDE BY 20 FEET LONG LOG OR STEEL BRIDGE INFILTRATOR/FILTRATION TRENCH SECTION E.SALMON GROTTO-SALMON EDUCATION AND REARING CENTER. F. OFF CHANNEL POOLS-REPLACE FISH PASSAGE BARRIER WITH LOG WEIRS. GRA RETE 10/_(/.0541 ✓ -- — Qq)� - --------- -� -------J Ito tv 4�0 ,v �. EXHIBIT D-2 ALDERBROOK RESORT REMODEL SEPA DOCUMENTATION PROPOSED STORM WATER COLLECTION, _ - �� TREATEMENT, AND DISPOSAL SYSTEM eo.ou u moo' c ]OEM 1C . 00PU0'C a + n OD OO N tn N N + ' O ) m O + N + � rn + (D c. O If) _ N M OO d +Ch O tal !n U U j (N� U Vj t j Ld U U j > W W > m U > U 1 U1 > > > w m Ol W W m 0] > w —0. 6 .93 DATUM KZV —0.44% 5.00 N 0 , �D �� C � i( I nN (b O Lf) N N in M � a a � 0 OlMn aD O r. to N Na M� N D OO OO O 0 r-: 0 a � N N OilN 1 ^ N NN N 94+00 95+00 96+00 97+00 98+00 99+00 100+00 101+00 102+00 103+00 104+00 105+00 106+00 107+00 108+00 109+00 110+00 111+00 112+00 113+00 114+00 115+00 116+00 117+00 118+00 119+00 PROFILE - SR 106 EXTENSION ROADWAY SCALE: 1 "=200' - ---� - HOOD L` ~ O cc iiniffl EXHIBIT T3 ALL ERBROOK RESORT REMODEL SEPA DOCUMENTATION OVERVIEW OF THE PROPOSED TRANSPORTATION AND SITE IMPPOVMENTS PLAN VIEW - PROPOSED TRANSPORTATIONV ABV r.: .'E IMPROVEMENTS NOTE: 2' CONTOURS SCALE: 1 "=200' Grace Miller- Ltr Mraz 11-15-04.jpg Page 1 North Forty Lodging LLC / 22526 S.E.64th Place,Suite 210 Issaquah,Washington 98027 Telephone:425 369 9290 Facsimile:425 369 9008 NORTH P FORTY November 15,2004 Richard Mraz Senior Planner Mason County Planning Department Courthouse Building I 411 N.5th P.O.Box 279 Shelton,WA 98584 Re: Alderbrook Storm Drainage As-built Drawings Dear Rick: Enclosed are the marked up as-built drawings for the storm drainage system at Alderbrook. Since they have been marked up by hand, it may not be entirely clear what field changes were made. If you have any questions concerning the attached drawings, please contact our construction manager Loren Davis when he returns to the office on Monday,November 22. Very trulyyours, Bean P.McGinnis President Attachment Drawings CI1,C13,C14,C17 and C18 b. Ground: 1) Will ground water be withdrawn, or will water be discharged to ground water? Give general description, purpose, and approximate quantities, if known. No ground water will be discharged or withdrawn during this project. 2) Describe waste material that will be discharged into the ground from septic tanks or other sources, if any(for example, Domestic sewage: industrial, containing the following chemicals . . .; agricultural, etc.). Describe the general size of the system,the number of such systems,the number of houses to be served (if applicable), or the number of animals or humans the system(s) are expected to serve. Alderbrook has a sewage treatment plant with a deep water outfall that has been approved by Washington State Department of Health and Mason County. The previous owner of the resort, Crista Ministries, has a separate project underway to extend the wastewater outfall an additional 1,500 feet into deeper waters(from 55 feet to 155 feet). The Brookside Building currently has a septic system, which will be abandoned and decommissioned following county and state guidelines. The Brookside building will be tied into the existing sewage treatment plant with a small sewage pump station and a 2"PVC force main. Due to the relocation of SR106 the Raikes and McConkey residents, currently on septic systems,will have their septic systems abandoned and decommissioned following county and state guidelines. The Raikes and McConkey residents will be tied into the existing Alderbrook sewage treatment plant with a small sewage pump stations and a 2" PVC force main c. Water Runoff(including storm water): 1) Describe the source of runoff(including storm water) and method of collection and disposal, if any (include quantities, if known). Where will this water flov"'' Will this water flow into other waters? If so, describe Existing storm water drainage facilities The existing site and roadway storm drainage system shown is shown in Exhibit D-1 and described as follows: 1. There is a small intermittent hillside drainage located just east of the wastewater treatment plant the flows into a catchment and then under Beach Drive into Alderbrook Creek through a 12—inch concrete pipe. The 12-inch pipe and catchment is easily plugged with debris and is typically a maintenance problem during the rainy season. 2. The hillside above the southeast parking lot flows into an interceptor ditch on the south side of the parking lot and then flows east to a small stream that flows through private property to Hood Canal. 3. The portion of the site located north of SR 106 and south of the existing motel buildings drains into a catch basin located at the southeast corner of the motel 31 buildings. The catch basin discharges into a 12-inch concrete storm water outfall located on the east boundary of the site. 4. A major portion of SR 106 and the central area of the existing parking lot drain into a catchment area just east of the resort lobby. The stormwater then flows through the resort interior stormwater piping system to a 12-inch concrete outfall that discharges into Hood Canal. 32 5. The existing gravel parking lot, located on the west side of Alderbrook Creek and in the southwest corner of the site, drains to the SR 106 roadway ditch and then flows west to an 18-inch culvert crossing of SR 106. The stormwater then flows to Hood Canal through a stormwater piping system that crosses private property. 6. The cottage area stormwater runoff flows overland to the base of the hill where it is intercepted by a small area drain that discharges to an 8-inch concrete pipe that outfalls at the existing concrete bulkhead. The existing storm water drainage system does not contain any facilities for the treatment or detention of storm water. The resort and SR 106 stormwater runoff are conveyed through the same catchment and piping systems. Proposed storm water drainage facilities: A contemporary stormwater collection system has been incorporated into the Alderbrook and SR 106 site design that will separate clean water runoff from impervious surfaces runoff. Clean water runoff is not required to be treated before discharge,while the road and parking lot impervious surfaces runoff will be treated before entering Hood Canal (Exhibit D-2 &D-3). This treatment system incorporates"low impact drainage" facilities intended to mimic natural drainage conditions on site. Low impact features, such as, open ditches, swales, and infiltration facilities will treat the SR 106 and site impervious surface runoff prior to discharge off site. These low impact facilities would be designed in accordance with the Washington State Department of Ecology Stormwater Manual (2000). The proposed site stormwater management system(Exhibit D-2 &D-3) is described as follows for the eastern, central, and western portion of the site and SR 106: 1. Drainage flowing north from the watershed above the proposed roadway cut will collected in a 2-foot deep ditch constructed along the top of the cut(Exhibit D-2, #1). A 12-inch diameter curtain drain will be installed below the surface of the drainage ditch to intercept groundwater interflow. The eastern half of this clean runoff and the intermittent drainage channel at the east end of the roadway cut will be directed through piping to a control structure(Exhibit D-2,#2)which will allow a controlled portion of the runoff to flow through the existing drainage channel (Exhibit D-2, #3). The westerly half of this clean runoff will be directed to a new discharge point in the intermittent drainage channel east of the sewer treatment plant and then through a 24-inch culvert and cobbled channel to Alderbrook Creek(Exhibit D-2, #IA) 2. The stormwater runoff from the proposed roadway cut slope will flow downslope to a drainage ditch alongside the road(Exhibit D-2, #5)where it will flow easterly to the control structure(Exhibit D-2,#2)where it will be piped to a new clean water discharge point at the east corner of Alderbrook (Exhibit D-2, #4) 3. Storm water from the eastern portion of the realigned SR 106 will be collected in catch basins and directed into a 120-foot long combination bioswale and infiltration trench(Exhibit 34 D-2 #6) for treatment before discharging through the existing 12 inch outfall at the northeast corner of Alderbrook(Exhibit D-2, #7). 4. Stormwater from the parking lot directly in front of the resort will flow northerly through trench drains and curb stop scuppers into a 240-foot long combination bioswale and infiltration trench(Exhibit D-2 #8) for treatment before discharging through the outfall at the northeast corner of Alderbrook(Exhibit D-2, #7). 5. Stormwater for the loading dock area will be collected in a catch basin and be piped through existing storm drainage pipe under the Plaza building to an oil water separator and then will flow into a 1,500 gallon septic holding tank(Exhibit D-2 #9). The low flow runoff will discharge from the septic tank and be further treated by flowing through a 56-foot long, 6- foot wide infiltration trench. High flows not needing treatment will flow through an overflow pipe to the existing 10-inch outfall east of Alderbrook creek. The 1,500 gallon septic tank will also incorporate shut off valves and an overflow pipe to the sanitary sewer pump pit that would allow spills at the loading dock to be isolated at the septic tank and (pumped into a tank truck for disposal at an expectable offsite location. 6. The roof drainage and foundation drainage (Exhibit D-2, #10)will be isolated and will be piped to a new clean water discharge point at the northeast corner of Alderbrook(Exhibit D- 2, #4). 7. The storm water runoff from Beach Drive,the proposed maintenance building area(Exhibit D-2, #11 and the westerly parking lot area(Exhibit D-2, #13)will be piped to the bottom of the hill and allowed to seep into the ground through a stormwater infiltration gallery(Exhibit D-2, #14). The lawn behind the bulkhead next to the beach will be rebuilt with previous gravel and sand to allow the stormwater to seep through the gravel out through the bulkhead. Runoff from the maintenance building paved areas will be run through an oil water separator (plate separator)before discharge to the roadway ditch. The maintenance area parking lot will be constructed with a gravel surface over 12-inches of ASTM sand so as to provide treatment through filtration before flowing to the roadway ditch. 8. Substantial improvements are planned to Alderbrook Creek(Exhibit D-2, A,B, C, D and E) as previously discussed in the environmental checklist. No impervious surface runoff from the site or roadway will be discharged into Alderbrook Creek. Overland flows from the vegetated areas will drain into the stream. The small drainage that flows from the Type 5 drainage stream,just to the east of the wastewater treatment plant,will be piped under the proposed SR 106 roadway into Alderbrook Creek through a 24-inch CMP pipe. 9. Approximately 600 feet of the existing SR 106 drains to Dalby Creek(.44 acres of pavement),while approximately 550 feet of the existing SR 106 drains to Big Bend Creek, (0.34 acres of pavement). The westerly 1,200 feet of the proposed SR 106 realignment will drain to Big Bend Creek(.94 acres of pavement). There will be an increase in the runoff from SR 106 that flows to Big Bend Creek while the runoff from SR 106 entering Dalby Creek will be eliminated. The water quality impact of the increased roadway runoff to Big Bend Creek will be mitigated by installing a 3-foot wide by 3-foot deep storm water 35 infiltration ditch (See Exhibit D-3, #15). The storm water will enter the ditch and percolate down through sand or pea gravel to an 8-inch under drainpipe. The under drain pipe will discharge into Big Bend Creek west of the proposed Dalby Road intersection with SR 106. The proposed storm water drainage collection and treatment system will greatly improve the quality of run off entering Hood Canal. Surface pollutants and road oils will be largely removed as water filters through the oil water separators, bioswales and infiltration trenches. 2) Could waste materials enter ground or surface waters? If so, generally describe. Waste materials are collected and pumped to the sewage treatment plant prior to entering hood canal. The existing on site septic system will be abandoned, to stop the possible contamination of ground water. The existing Grease Trap located in the Alderbrook stream buffer will be abandoned and replaced with grease traps located in the commercial kitchen. The grease barrels and compactor will be located in the stream buffer, but will be maintained in an enclosed structure. d. Proposed measures to reduce or control surface, ground, and runoff water impacts, if any: Refer to 5.c-1 above 4. PLANTS: a. Check or circle types of vegetation found on the site: x deciduous tree: alder, maple, aspen, other _x_evergreen tree: fir, cedar, pine, other shrubs x grass pasture crop or grain x wet soil plants: cattail, buttercup,bullrush, skunk cabbage, other water plants: water lily, eelgrass, milfoil, other other types of vegetation b. What kind and amount of vegetation will be removed or altered? The realignment of SR106 will pass roughly parallel and 200-feet south of the old section and require clearing of 7.4 acres of second growth forest (Exhibit P-1). Approximately 4.3 acres of this forestland will be terraced and landscaped with native vegetation (Exhibit T-3) to merge naturally with upslope second growth forest. The remaining 3.1 acres will be in impervious road surface and roadside slope. 36