The URL can be used to link to this page

Home My WebLink AboutEngineer's OWTS Design Plan129 CAINS LANE CARBONDALE, CO 81 623 970.309.5259 CARL-A.OSTBERGCaGM AI L.COM September 5, 2024 Project No. C1900 Mike Premich W h ite ri vercon stru ctio n co Cal ama i i. co m Subsurface Investigation and Onsite Wastewater Treatment System Design 4-Bedroom Residence Lot 23, Homestead Estates Garfield County, Colorado Mike, CBO Inc. performed a subsurface investigation and completed an onsite wastewater treatment system (OWTS) design for the subject residence. The 10.069-acre property is located outside of Glenwood Springs, in an area where OWTSs and wells are necessary. Legal Description: Section: 24 Township: 6 Range: 88 Subdivision: HOMESTEAD EST. Lot: 23 Parcel ID: 2187-243-00-023 SITE CONDITIONS The property is currently undeveloped. A 4-bedroom residence is proposed The residence will be served by a private well on the property. The well is located to the northeast of the proposed residence. The well is located greater than 50-feet from the proposed septic tank and greater than 100-feet from the proposed soil treatment area (STA). The proposed soil treatment area (STA) location has an approximate 5 to 6 percent slope to the southeast. The proposed area is vegetated with sage and native grasses. There should be no traffic or staging of material over the future STA site to avoid compaction of soils prior to construction of the STA. SUBSURFACE The subsurface was investigated on June 28, 2024 by digging three soil profile test pit excavations (Test Pits). A visual and tactile soil analysis was completed by Carla Ostberg at the time of excavation. I The materials encountered in Test Pit #1 consisted of medium brown clay loam topsoil to 3.0-feetwhere digging refusal was encountered on a large boulder. No bedrock or groundwater was encountered. The materials encountered in Test Pit #2 consisted of medium brown clay loam 4.0-feet, underlain by medium brown clay loam with pockets of reddish brown clay to a maximum depth explored of 5.0-feet where practical digging refusal was encountered. No bedrock or groundwater was encountered. Carla Ostberg holds a Certificate of Attendance and Examination from the CPOW Visual and Tactile Evaluation of Soils Training. Page 2 A sample of the soil was taken from Test Pit #1 at 3-feet below grade. Soil structure grade was moderate. The soil formed a ball and a ribbon 1 to 2-inches in length before breaking. Soil structure shape was blocky and consistence was friable. Soil texture was both gritty and smooth. We also viewed a previously excavated Test Pit near the house foundation. It was excavated to a maximum depth explored of 7.0-feet. We have labeled this Test Pit #3, but it is described in Kumar and Associate's report (enclosed) as Pit 7. A gradation was performed on a sample from Pit 7 and is described below. The subsurface was investigated by Kumar and Associates, Project No. 23-7-2024 and is documented in a report dated July 15, 2024. Seven Test Pits were excavated surrounding the proposed foundation. The gradation on a sample taken from Pit 4 at 4.5 to 5.5-feet consisted of 40% gravel, 30% sand, and 30% silt and clay. A gradation on a sample taken from Pit 5 at 3.0 to 4.0-feet consisted of 14% gravel, 48% sand, and 38% silt and clay. A gradation on a sample taken from Pit 7 at 4.5 to 5.5-feet consisted of 31 % gravel, 22% sand, and 47% silt and clay. Pit 7 profile consisted of topsoil (clay, silty, slightly sandy, organics, firm, slightly moist to moist, gray) to 2.0-feet, underlain by clay (sandy, scattered gravely to gravelly, stiff to hard, slightly moist to moist, brown) to 4.0-feet, underlain by gravel and cobbles (sandy, clayey, occasionally silty with boulders, basalt rock, dense to very dense with depth, moist, dark brown) to a maximum depth explored of 7.0-feet. No bedrock or groundwater was encountered. We have researched soils in the area through USGS Web Soil Survey. The report is enclosed. The area of the proposed STA is identified by map unit symbol 19. The map unit name is Cochetopa-Antrobus association, 25 to 50% slopes. Typical soil profile from 0 to 3-inches consists of loam, 3 to 38-inches consists of clay loam, and 38 to 60-inches consists of gravelly clay loam. Based on information provided from the available documented resources and our knowledge of soils in the area, soils are consistent with Soil Type 3, Clay Loam with moderate structure grade. A long-term acceptance rate (LTAR) of 0.35 gallons per square foot will be used to design the STA. - VW AM Test Pit #1 Ilkti Clay loam topsoil with sporadic large boulders Sieved sample Test Pit Pit #1 AdOw Ribbon 1 to 2-inches in length Page 3 Page 4 �t ? • � a Looking toward Test Pit #2 Similar bouldery conditions id IL Test Pit #2 r}' f y� f +ram._• r Test Pit #2 i x , w Pit 7 (previously excavated) yp��Y 1 Page 5 Page 6 DESIGN SPECIFICATIONS Design Calculations_ Average Design Flow = 75 GPD x 2 people/bedroom x 3 Bedrooms + 75 GPD (41h Bedroom) = 525 GPD LTAR = 0.35 GPD/SF 525 GPD / 0.35 GPD/SF =1500 SF x 1.0 (gravity trenches) x 0.7 (chambers) =1050 SF / 12 SF/chamber = min. 88 'Quick 4' chambers The OWTS design is based on 4-bedrooms. An average daily wastewater flow of 525 GPD will be used. For the purposes of this OWTS design, Benchmark Elevation at grade 8756' has been established as 100' (Finished Floor). CBO Inc. should be notified of any discrepancies or problems with grade elevations of proposed components during installation of the OWTS. OWTS Component Primary Tank Inlet Invert Distribution Box Minimum Elevation Approximate horizontal distance 29' / min min. 7.25" fall Approximate horizontal distance 48' / min min. 6" fall 2% fall / 1 % fall / Infiltrative Surface Approximate horizontal distance 45' to furthest _ trench / min. 1 % fall to STA / min. 5.625" fall _ *Elevations are based upon standard OWTS installation practices. Component elevations may change during installation due to site conditions. Minimum grade refers to piping between components. The 4-inch SDR-35 sewer line exiting the residence must have a double -sweep clean out and a minimum 2% grade to the septic tank. The system installation must include a minimum 1250-gallon, two -compartment septic tank with an Orenco® Biotube effluent filter on the outlet tee. We have specified a 1500-gallon, two -compartment Infiltrator® poly septic tank. Any state -approved poly or concrete septic tank may be substituted. Risers must bring the manhole lids to grade for access. If more than one riser is added to the septic tank, an extension handle must be installed on the effluent filter. Effluent will gravity flow to a distribution box, and then to six gravelless chamber trenches. The distribution box must be accessible from grade and must have flow equalizers, or similar product, installed on each outlet pipe in the distribution box to assure equal flow to each trench. Each trench will consist of 15 'Quick 4' Standard Plus Infiltrator® chambers for a total of 90 chambers and 1080 square feet of infiltrative area. There must be at least 4-feet of undisturbed soil between each trench. Inspection ports must be installed at the beginning and end of each trench. Ports may be cut to grade and placed in sprinkler boxes for access. COMPONENT SPECIFICATIONS The component manufacturers are typical of applications used by contractors and engineers in this area. CBO Inc. must approve alternative components prior to installation of the OWTS. Requests must be submitted, in writing, to our office for approval prior to installation. Component technical data sheets are available upon request. Page 7 COMPONENT MANUFACTURER I MODEL NO. COMMENTS Septic Tank Infiltrator® IIM-1530-2CP 1500-gallon, two - compartment poly septic Effluent Filter Orenco® 4" diameter full size filter Tank Risers and Lids Orenco® Double -walled PVC Rise Lids (24" diameter) :)n Box Polylok (Distribution box, risers, lid, flow equalizers (4) rs Infiltrator® 'Quick 4' Plus Standard 90 'Quick 4' chambers Chamber Construction must be according to the jurisdiction's adopted On -Site Wastewater Treatment System Regulations, the OWTS Permit, and this design. PERMIT APPLICATION INSTRUCTIONS An OWTS Permit Application must be submitted to Garfield County Environmental Health Department. ht# s:/Iwww. arfield-coup .com/environmental-health/files cco/sites/1610WTS-A lication-Com lete- Packet-Dec.-2019.odf. If the OWTS Permit Application will be submitted with a Building Permit Application, it should be submitted directly to Garfield County Building Department. All questions regarding permit submission can be directed to Garfield County Environmental Health Department, 970-945-6614 x8150. INSTALLATION CONTRACTOR CBO Inc. expects that the installer be experienced and qualified to perform the scope of work outlined in this design. The installer must review this design thoroughly and coordinate with our office in advance of installation. Any additional conditions in this design or county permit must be completed and documented prior to final approval of the OWTS installation. Communication between the installer and this office is expected throughout the installation. INSTALLATION OBSERVATIONS CBO Inc. must view the OWTS during construction. The OWTS observation should be performed before backfill, after placement of OWTS components. Septic tanks, distribution devices, pumps, dosing siphons, and other plumbing, as applicable, must also be observed. CBO Inc. should be notified 48 hours in advance to observe the installation. In an effort to improve the accuracy of the record drawing, we request that the installer provide a sketch of the installation, including path of the sewer lines, water line installation (if applicable), septic tank location, STA location, and measurements from building corners or another fixed objects on the property. This sketch is most easily provided on Sheet W2.0 of the OWTS Design Packet. Photographs of the installation and final cover are also requested to supplement our installation documentation. REVEGETATION REQUIREMENTS An adequate layer of good quality topsoil capable of supporting revegetation shall be placed over the entire disturbed area of the OWTS installation. A mixture of native grass seed that has good soil stabilizing characteristics (but without taproots), provides a maximum transpiration rate, and competes well with Page 8 successional species. No trees or shrubs, or any vegetation requiring regular irrigation shall be placed over the STA. Until vegetation is reestablished, erosion and sediment control measures shall be implemented and maintained on site. The owner of the OWTS shall be responsible for maintaining proper vegetation cover. OPERATION INFORMATION AND MAINTENANCE The property owner shall be responsible for the operation and maintenance of each OWTS servicing the property. The property owner is responsible for maintaining service contracts for manufactured units, alternating STAs, and any other components needing maintenance. Geo-fabrics or plastics should not be used over the STA. No heavy equipment, machinery, or materials should be placed on the back -filled STA. Machines with tracks (not wheels) should be used during construction of the STA for better weight distribution. Livestock should not graze on the STA. Plumbing fixtures should be checked to ensure that no additional water is being discharged to OWTS. For example, a running toilet or leaky faucet can discharge hundreds of gallons of water a day and harm a STA. If an effluent filter or screen has been installed in the OWTS, we recommend this filter or screen be cleaned annually, or as needed. If the OWTS consists of a pressurized pump system, we recommend the laterals be flushed annually, or as needed. The homeowner should pump the septic tank every two years, or as needed gauged by measurement of solids in the tank. Garbage disposal use should be minimized, and non -biodegradable materials should not be placed into the OWTS. Grease should not be placed in household drains. Loading from a water softener should not be discharged into the OWTS. No hazardous wastes should be directed into the OWTS. Mechanical room drains should not discharge into the OWTS. The OWTS is engineered for domestic waste only. ADDITIONAL CONSTRUCTION NOTES If design includes a pump, weep holes must be installed to allow pump lines to drain to minimize risk of freezing. The pump shall have an audible and visual alarm notification in the event of excessively high- water conditions and shall be connected to a control breaker separate from the high-water alarm breaker and from any other control system circuits. The pump system shall have a switch so the pump can be manually operated. Excavation equipment must not drive in the excavation of the STA due to the potential to compact soil. Extensions should be placed on all septic tank components to allow access to them from existing grade. Backfill over the STA must be uniform and granular with no material greater than minus 3-inch. LIMITS: The design is based on information submitted. If soil conditions encountered are different from conditions described in report, CBO Inc. should be notified. All OWTS construction must be according to the county regulations. Requirements not specified in this report must follow applicable county regulations. The contractor should have documented and demonstrated knowledge of the requirements and regulations of the county in which they are working. Licensing of Systems Contractors may be required by county regulation. Page 9 Please call with questions. Sincerely, CBO Inc. Carla Ostberg, MPH, REHS . 1 L 1 1 i r 1 +tr f .. • ' . r� p . \1 \ y !1 i f I � -' y l � 1 � l �l •1 � � r l '1 }. � ' �� ) r I J 1 y ■ r 1{ I 1V�y i n -'''y f L m i 1 1 1 y ■ ]! r }� ! y r .s l 1 r l l L mc _ yzz 000 avr ! I t S r t , 7 { / I I Ilyy � � z a p,i c {{ .1 1 t 1 \ 1 { r■ 1 ! 1 L:-fir • lk!4, 1 1 \ �, yy y ■ ti� 1 y l 1 ! 1 $L 1 1 I "O'c 0 1 \,\\• ■ 1 \ 1 yl 11 1 �ti.. ly ( i= \.r ■lyl 4 +. + m o m m ■ ■ 1 1 1 1 { L! ■ { i o Q O W,EP ym 1 ■ ■■ 1 l f i ■ \ t1{ 4 1 1 ! r' 1 1 J f `° °-'•moo I{ JtI/ 1 i f\J� 1rs�- 1 a / 111`' ., ,, r •� f r -� y", ■ 1 r ( , w 1 � \y y•\1 I Ste{ {rf ti � 1 11 �+I/ / ■ /J � � � yJ , L��1 { S r l�rfJ1 1 .q ,{I❑ } 1 1 __e �{rr 1 ti \ J \`} I `1 `I r �r r ■, �J,rrr� `� ,ram J�� i► ! 1{ti ra 11 . 1 ■ j !1 J I �t{ J �Jlf 1! 1 �!r_� r�1--J'�J / �� J � a 4 � y .y �r 1 � r •ter ; \ ` y'c: fry r fJ J � r'r—• � � � r rl_ L � J��ti �� mm r 1 r fi till I r m a r r•� } 2O I .� 1 \ `off m ■ 1■ �.. l 7 � r t r■. r � y Lr � �� 1 � rr• -. � -- � � y r 'D o. N m I /r 1 It z I Al�R_M CD CD 1 \ .. nn C1 oN - 1j - 1 CD CL CD 1■`'�`l�-4 ` _k ti � � ti ` `-�ir i' Plyy '� \^_ � �l l /� ^/�` may r ' { 5r i r `per �• �.�i �1SM1�(� tj /~ "` { a � ti_ ... �---■ f �• �. "� `• � � �. -��— .r wflll�{tip I �� 1\ i_ _ f� s2=o m yu "$o=ym 1J 1. / jam` c� / ■ �w r r /f r l �m} \■L� J +. �� / \off/�;:' f�/rlft lr g?m�yya �� `■` .. � ■` ! � � r f lfl��"/1111�I�r x�� \ i�i 1 v ` r+'• 4 •-r ^��/f -I/�� I%r�f�J1 ,�r Fr��/�'��, �� am /• ` 0 a 8,a � + �, ■� �Ir v Iti \1 i fj�/J�gf�/I��frft�/1�•{F � ti ,\-, au -as I 0 o m�=x � {■ I~' J��■ ■ram If.��I�11/�IIIIf�'II/f/rrJir� i� � L; ?� � p6Nc�� O 1 �NA� ■ f�� .� 1 f �� f��■� �!�t///r�/��///%/FJf jtf,/ r`rtilJ t a W N 1 $�i�xn�� S r-•�--"`' Iw/■fRl r,^ ��11 ��r/i�fjrf�fi�—� ��^■ r y Hum O a -'� Inc��m1° yr .J� .-1--��-�•"�I ^J�-^r// rjf if ff/I//!. !'l ._ nar 1 }--.�1 4 m ` vm+w �'m-i{�'fl .-.tip 4`� ��It��r� � i��'•�a��i'f��/•:fj ��``• � —�� 1 I , o � _ � � �� r w�,. i � �i�r�/��f�� fJ/ft�`f 1..rlr •—��/ �� ItY ti a � .• � r l r ..» j r f !.//J r�ii'�fr % y 1 fIf f f f• f� � i 1 �� I,f \s I ��` ~�— _�'--- i r>r•triri��f..rtr �frr�-��•f,:_ y � 'l} 1 1 ( �m 0,m zv / ma�'� �z Tcn T! m� Quo y J m cvno�ou I j5 o m7J �o m f �� I zO, ZED Om m3\ m o r 3 p I m 1 }Z]p \ o I 'o M�)m �M n \ mi I L\ ?� m0 / W ft. n J1 \ m oy Wo" � \ ?D \ ``■ xz l •� m o on 1 In 1 r- T 1' v o \ 1Z m L L- / m .2 { _ D \ m f' me 1 0� / ^\z� mo 05 Z�'^' Do7 I r r m r} 0 0 0 / O ( v I D - ,._ m \,Y T w z c o 3 3 �^' \ \\•..� h 3 c mCL \ �0 o rm Q o a ^' / 1 r j m CD 0 Z m W A \ I cmi 1 z z m 1 (m2 Ion mrn O-{p \ <_0' oo4, 1 X --I I I �Z1 OAK m - W vo v m3= f T m \ 1 I �mm I D/ C ', r n \ \ cnA n O > D rn /in Q o 0 r- \ 1 l zo m O A I m \ OZ1 ` \ I cn 1 cn m b \ O m= , \ A N \ A O , )r \i }.\ / m (2 , [f/77 200 M. k¢// k )) » \,« % _0 2 §`\ m ;D f \ \ 0 § { m ou - 0 § /]« _x { ` - X0 / �� \00 \ + 0 m 0m 0 3 n_ § { ( 2 - O �EE� j - - 2255 @O § 0 - § - z0- k \O 2 2 ® m (\�� § Q , \2\� § \� lomx ) )/ Er/ ®§( C. ! k |mm ®` �/} I /\ m� m� c § 600 |\ TOk 2 ` « !; �k �§ < 0* 2: _ ,i k \ la Ll § 7Fn / 0 - ! - _ \ } } ) �/ _ - ) k o _ § 2 ' _ - | \� o k \ w / o DEPTH -FEET //\\? \ /)§ m oo\jE m =oo = 2@ -n = = w I /33 $ w �x\mm / $x2 - �m \� GJ)> i Mm }\0 t \( 2ƒ ! § o \ \ Z \ 7 k ¥ > r \/.� �� > ccm o i \ / k k :{ N/ 2 - 44Rz> z 11$o 3C? c$ » E§q9 ® \�� ) (3 { m > / o f m 71 \ 77//.. § ]2k z £ 00m°— xz � ` \*\> I \q $ C:) ) § ƒ -6 / m 0 , /fU)m 00q\ 2` a\ / f -n j / j § k ( �� z 3 m1 , q / §( §) \ ) o r z\ § 2 x( (0 ) _ � \kj/o }o = 2 (§ \#c\§§) o�■ i-o A) . °§ f« ) ]�`§ ) )