Loading...
HomeMy WebLinkAboutHIGHLAND TERRACE ADDN #6 General InformationH i hlo nc HEWITT V, LOUNSBURY & A$SOCIATE~ ENGINEERS PLANNERS SURVEYORS 72 3 W. 6th. Avenue, Anchorage, Ak. 9950i Tel.(907) 272,5451 March 19, 1974 Platting Authority Greater Anchorage Area Borough 3500 E. Tudor Road Anchorage, Alaska 99507 Subject: Highland Terrace Subdivision, Addition No. 6 Gentlemen: We respectfully request that the subject plat be approved without further on-site soils investigations. This request is being made based on a thorough review of soils data performed by our firm and the Greater Anchorage Area Borough, Department of Environmental Quality, on property near and adjacent to the proposed plat. We wish to cite five separate soils report which are enclosed for your con- venient review. Report #1 was performed by this firm in July of 1973 on the Highland Terrace Subdivision, Addition No. 4, approximately 1,200 feet to the Northeast. The test hole excavated on Tract 5 indicates that on-site develop- ment can be accomplished using a design factor of 225 to 250 square feet per bedroom. Report #2 was performed on Lots 1, 2 and 3, of 'the Donaho Homestead, Addition No. 1, this winter by this firm. This report indicates a design factor of 200 to 225 square feet per bedroom. This property is located ap- proximately 1,200 feet Southwest of the proposed subdivision. Report #3 and #4 are soils logs performed by Greater Anchorage Area Borough, Department of Environmental Quality, in June of 1972. Report #3 indicates a fairly gravelly soil and a design factor of 105 square feet per bedroom. Report #4 indicates a siltier soil with a design factor of 225 square feet per bedroom. Report #3 is approximately 1,500 feet Southwest of the proposed project. Report #4 is approximately 800 feet Southwest of the proposed subdivision. Report #5 is a soils log performed by the Greater Anchorage Area Borough, Department of Environmental Quality, in July of 1973. This report is on Lot 2 in Highland Terrace Subdivision, approximately 500 feet West of the proposed subdivision. This report indicates a design factor of 100 square feet per bedroom which does not coincide with the soils log. Based on the soils log in the report, we would indicate a design factor of 200 to 225 square feet per bedroom. Based on the above reports, we feel that the proposed subdivision can be safely designed with seepage pits based on a 4-bedroom home and a 250 square feet per bedroom seepage pit wall area. Assuming a 6 foot depth of seepage Platting Authority Greater Anchorage Area Borough March 19, 1974 Page Two wall, the seepage pit would be approximately l0 feet by 17 'Feet. l'he proposed lot layout is adequate, both in size and topography, to allow the placement of on-site disposal systems and a safety factor of at least one additional seep- age pit should the first seepage pit ever fail. Thank you for your consideration of this subdivision. Respectfully submitted, HEWITT V. LOUNSBURY & ASSOCIATES Charles S. Mortf~er, P.E. CSM/erq Enclosures 0 tt V ,'V 0 0 GEOLOGIC SOIl_ INVESTIGATION OF tlIGttI_AltD TERIIACE SUBDIVISION, ADDITION NO. 4 A Portion of the NE 1/r~, Section 7, Township lq North~ Range 1 West, Seward Meridia.n,.Alaska July ll, 1973 PREPARED FOR: Paul Jones Eagle River, Alaska PREPARED BY: Ilewitt V. Lounsbury & Associates 723 W. 6th Avenue Anchorage, Alaska 99501 W. O, #73-34] TABLE OF CONTEIfr$ INTRODUCTION SITE DESCRIPTION FIELD INVESTIGATION SUB-SURFACE COI~DITIONS CONCLUSIONS AND RECOMMEliDATIONS LOCATION MAPS, TEST LOGS AND DATA I [ITRODUCT I This report is the result of field investigations conducted July 6, 1973, on propert'ies ill the Eagle River area, Greater Anchorage Area Borough, known as Highland Terrace Subdivisign, Addition bio, 4, Portions o'F this subdivision under investigation comprise al)out eight acres. The purpose o' the, investigation was to determine feasibility of the proposed subdivision of certain tracts within the area, SITE DESCRIPTION The property under investigation is in its natural state except 'For gravel roads leading into and through the property. It is located on the slope of the Ci~ugach Mountains and is moderately steep in gradient al- though smooth and regular in contour. There are no large defined drain- ages on the properties under investigation, Average elevation of the site is around 1,200 feet above sea level. Most of the area is covered by dense trees of birch and spruce. Other areas are covered by alder and grasses. Drainage is to the Southwest and. West, FIELD INVESTIGATION Soils investigation consisted of four test trenches dug with a Case 580 Backhoe. Visual inspection was made and logged in this report. Road cuts were also observed within the area, A road cut South and East of Test Hole #1 revealed exposed fractured bedrock (see Location Map). That area also showed exposed very large boulders. Test IIole #3 was excavated to a depth of four feet and encountered rock. Location of Test lto'le t/3 was moved to all adjacent area and re-excavated to a depth of 3.5 feet where we encountered rock. Other areas shown on the Location Map could not 'Feasibly be penetrated with the existing equipment due to the steep- ness of tile terrain and density of tile vegetation. SUB-SURFACE CONDITIOitS Various publications define the geology of the immediate area as morainal deposits (till) and bedrock. This was confirmed l~y the field investigation of tile test holes and the road cuts. Poorly sorted mixed deposits of sand, gravel and silt were visible in all test holes. Under- laying material, boulders or bedrock, were visible in Test Holes #2 and #3. The glacial material is in all cases overlain by a variable thick- ness of brown, loose silts and organic materials characteristic of the en-- tire area. From field observations, it appears that the depth of the morainal till layers are extremely variable and should'be considered on a strictly local basis. No water or seepage was encountered in any of the test holes,' Frozen ground, however, was encountered in all test holes. CONCLUSIONS AND RECOMMENDAIIONS The following conclusions are made from the field investigations herein described. Portions of the site are suitable for the proposed residential development. l. Tract 5. This site appears adequate for an on-site disposal system. A design factor of 225 to 250 square 'Feet per bedroom is recommended. Any proposed on.-site disposal system, well or dwelling should be located to be compatible with the steep gradient of the terrain. Tract 7. Test Holes #2, #3, and #3A revealed bedrock or very large boulders very close to the ground surface. Due to the low permeability characteristics of the soils revealed by these test holes, subdivision and/or development of this ~ract is not recommended at this time. Future geologic investi- gations may reveal suitable soils on the West (lower) portions of these proposed lots. However, suitability cannot be deter-. mined at this time. ' Respectfully submitted, HEWITT V. LOUHSBURY & ASSOCIATES ~S S. M'ortTFFer, P.E. FEET 17 ' I Dot~ ~Tc~un Dote Completed Pro]oct Nome ~ocotion Method Used Field P~rty __ LOG OF ?'?ZST b'O~,ING Sampling DL~CI~IPTION Soil 1½'po~ color~ lo~Vuro, osh?nalod porh'c!o s/'zcj ~ sampler drlvin~ no/es~ [ deplhs Cl~culcllion Io~I~ ~ hi,'~ u~ed~ etc. Ifolo No. Sheol ?'o1~1 Doplh Locatlbn /,/g/es £ ?rajecl l¢ome, _. Location Method Used __ Field Pc/ri? . ICeolher I_ OG OF TEST UOI~IIVG II¢'~WII V. L ounshuO, Sampling Eng/neors -- Surveyors Anch'or~ge~ . Ala~ko DESC/~IPZ'ION Soil lype, co,'or~ lexlure, e$timolod porh'c!e size~ sum?/er driWn..g notes~ depths c~colalion lost, holes on cL,'ilhng eose~ hi,'s used, tlc. Hole No. Sheel ~ of i'olal Deplh · Locohbn [Voles £ [ I Dole ~egun Dote Completed Project Nome__ ~(ethod Used ~ Field P~rty Weofher Sampling Sheet ~' of ?'oral Deplh ~'~ . ~? Ground Wolet' Time __ ~Dale ~Dble DEb'CH/PT/ON $~il lypo~ co/or, lexture, eslk~olod por/icle sizG sampler driving notes, d~pll~s circul~l[on iosf noles on dr/Ihng eose~ bHs u$od~ elc. Locatz~n Ilo/es £ Diagram., Vegelsl;'on: Ld £H913~^ ),.8 I. J3NI3 .I. N3O~3d SOILS REVIEW OF LOTS l, 2, AND 3, DONAHO HOMESTEAD, ADDITION #1 PREPARED FOR: Teddy Donaho P. O. Box 124 Anchorage, Alaska PREPARED BY: Hewitt V. Lounsbury & Associates 723 W. 6th Avenue Anchorage, Alaska 99501 SOILS REVIEW OF LOTS l, 2, AND 3, DONAHO HOMESTEAD, ADDITION #i SITE DESCRIPTION The subject property is designated as Lots 1, 2, and 3, Donaho ltomestead, Addition #1, described on the accompanying preliminary plat and located within the Southeast One-Quarter (SE 1/4 , Section 7, Town- ship 14 North, Range 1 West, Seward Meridian, Alaska The lots contain approximately 3.5 acres, and are bounded on the South and West by gravel roads. The land generally slopes to the South and West and is covered with a dense stand of small birch, brush alld scattered spruce. The ad- joining properties on the South and West have been subdivided. SOIL REVIEW The "Generalized Geologic Map of the Eagle River - Birchwood Area" by Schmoll, Dobroyolny, & Zenone shows this area to be a combination of coarse-grained alluvium terraces, and mixed coarse and fine-grained glacial morraine deposits, Our test pit log closely parallels this general classification. The road cut bordering tile West property line shows similar soils, possibly containing a higher percent of gravel closer to the surface. Based on the information acquired from field investigations, we make the following recommendations. l. Seepage pits should be based oil a design factor of 200-225 square 'Feet per bedroom. 2. Top of the seepage pits should be located at or below 3.0 feet to utilize the above design factor. 3. It is recommended that seepage pits on Lhe Northern most two lots be set as deep as possible to guard against the seepage surfacing along the road cut; also that seepage pits be located to the East and North of the house locations, away 'From the road. 4. All existing State and Borough requirements should be complied with. PREPARED BY: John R. Clark, P.E./George Grutsch 35D0 TUDOR ROAD ANCHORAGE, ALASKA 99502 Legal Descrintion: Lot Block This ~orm Renorts Soils Lofl~) Soil Characteristics F)eDth Feet 9 h~I ~ , In __ l'Z~(W~ Ground Water Encountered?.. /~ If Yes, At what Depth? Date Performed Subdivision Percolation Test Reading Date Gross Time Percolation Rate Minute Proposed Installation: Seename Pit Deuth of Inlet Net Time Depth to H20 N e t Dropi Drain Field . Depth To Bottom Of Pit Or Trench Test Performed By _ Data Certified By: Date: DEPARIHEIII OF EiI.,JkO;ii!E;I]'AI. QUALITY 3500 TUDOR RDAD ANCHORAGE, ALASKA 99502 Performed For Date Performed CASE 6'; -2 Lefla.1 .p~sFci.~.t~ o.n~:.- .Lot . .B1 o.c$: .S:ubdi,.visJ.on '""'"':'f~'S" F~¢m~:R~'~'O'~ts '~'"'o'~ ~'~'LO~.~~ '"'" ..... ' Percolation Test Qenth Feet Soil Characteristics 1 as Ground Water Encountered? /~/F, . C'?oz)e If Yes, At what Depth? Readinfl Date Gross Time Net Time Depth to H20 Net Drop ercolation Rate Hinute Proposed Installation: SeeDaae Pit Drain Field Den. th of Inlet Depth To Bottom OF Pit Or Trench cnM!~ENTS: 7'~ ?- _~- .s~c F~ Test Performed By Data Certified By: Date: ~ P'e'rf6rmed For GF [ER AHCHORAGE AREA BOROUG, DEPARTMENT OF ENV!~tONME!,ITAL QUALITY Case 3330 "C" Street ~o~[~.~NCliORAGE, ALASKA 99503 Legal Description: Lot ~ Block Subdivision_~/~/,'?~z/~~ - = This Form Reports Soils Log_~ Percolation Soil Test Must Be Logged To 4' Below Proposed Seepage System - Depth Feet Soil Characteristics 4~ 5--- 6~' 9--- lO--- 11-- 14--- /00 Was Ground Water Encountered? If Yes, At What Depth? Reading Date Gross Time Net Time Depth to H20 Net Dro Percolation Rate Minute Proposed Installation: Seepage Pit Depth of Inlet Drain Field Depth to Bottom of 'Pit or Trenc~ Test Performed BY_/~?F.~_ -~.' ~?~'F~_~ Date Certified BY: Date: ,Z .Z 3 7 ~./.Z o ~ -('}a / / '% ir) / / ' d~ :¢,4 r4 / / /