JUNE 1967

                HOUSEBOAT WASTES

                  Prepared by

                  B. D. Clark
           Technical Projects Branch
       U. S. Department of the Interior
Federal Water Pollution Control Administration
               Northwest Region
      Pacific Northwest Water Laboratory
               Corvallis, Oregon
                   June 1967
              Oept. of the Interior.

                        TABLE OF CONTENTS


    I.   INTRODUCTION	    1

        A.  Authority	    1
        8.  Purpose and Scope	    1
        C.  Problem	    1

   II.   SUMMARY	    5


        A.  Waste Quality	   11
        B.  Waste Quantity	   11


        A.  Houseboats	   18
        B.  Other Floating Structures 	   29

    V.   MOORAGE COLLECTION   	   33

        A.  Collection System	   33
        B.  Moorage Lift Stations	   40

  VI.   TREATMENT	   47

       A.  Individual Methods  	   47
        B.  Group Methods	   52


       A.  Basic Design Criteria 	   61
       B.  Layout and Cost Estimates	   63


  IX.  APPENDIX	   73

       Appendix A - Plumbing Costs  for Three Houseboats in
                    Seattle, Washington  	   75

       Appendix B - Design Curves for Multiple Pump
                    Systems	   79

                         LIST OF FIGURES
Figure                                                        Page
  No.                         Title                            No.
   1     Houseboat Water Use Pattern 	    14

   2     Houseboat Plumbing Plans  	    20

   3     Centrifugal Sump Design   	    27

   4     Recirculating Toilet and Macerating Pump
         Application	    30

   5     Walkway Connections 	    36

   6     Moorage Collection Costs  	    39

   7     Centrifugal Sump Pump Installation t	    41

   8     Moorage Lift Station	    42

   9     Extended Aeration Treatment Costs  	    55

  10     Floating Restroom & Sewage  Treatment Plant Used  in
         Conjunction with Boating and Other Marine
         Activities	    57

  11     Floating Restroom & Sewage  Treatment Plant Used
         with a  Boat Holding Station Evacuation System  ...    58

  12     Settling Tank and Chlorination Treatment  	    59

  13     System  Design	    62

  14     Design  Curves  for Multiple  Pump System for
         Various Inflow and Pumping  Rates   	    83

  15     Design  Curves  for Multiple  Pump System for
         Various Inflow and Pumping  Rates   	    84

                         LIST OF TABLES
Table                                                         Page
 No.                          Title                            No.
         Average Wastewater Quality from Three
         Individual Homes  	    12
         Quantities of Sewage Flow	    15
         Estimated Costs for Plumbing a  One-Bathroom,
         Single Story Houseboat with Copper,  Cast  Iron,
         and Plastic Materials    	    22
         Houseboat Plumbing and Pumping  Methods  Summary   .  .    32
         Comparison of Feces  and  Urine Waste  Quantities
         to Total  Household Wastes  for a  Family  of  Five
         People	    50
         Soil Absorption Areas  Required  for  Single
         Houseboats  for Various Percolation  Rates   	    53
         Cost  Summary	    69


     Methods of collection and treatment for houseboat and moorage

wastewaters are reviewed.  Several methods using alternative

materials are considered and approximate installed costs are

given.  Emphasis is on solution of the problem in the State of

Oregon but information developed is applicable in adjacent states

and elsewhere with appropriate adjustments.


      This study was made possible through  the  assistance  of  the

following State and local agencies and individuals:

                1.   Oregon State Sanitary Authority
                    Portland,  Oregon

                2.   Floating Homes Association
                    Seattle, Washington

                3.   Waterfront Property Owners  Association
                    Portland,  Oregon

                4.   King County Health Department
                    Seattle, Washington

                5.   City of Seattle Engineering Department
                    Seattle, Washington

                6.   Hersey Sparling Meter Co.
                    Seattle, Washington

                7.   City of Portland Water  Bureau
                    Portland,  Oregon

                8.   Parkrose Water District
                    Portland,  Oregon

                9.   Master Equipment Co.
                    Portland,  Oregon

               10.   Cornell Pump Co.
                    Portland,  Oregon

               11.   H.  D.  Fowler Co.
                    Seattle, Washington

               12.   DeFirs Moorage
                    Portland,  Oregon

               13.   Waterly Lane Moorage
                    Portland,  Oregon

               14.   Portland Rowing Club
                    Portland,  Oregon

15.  Mr. Terry Pettus
     Floating Homes Association
     Seattle, Washington

16.  Mr. Fred Repp
     Master Equipment Co.
     Portland, Oregon

17.  Dr. Donald Guthrie
     Professor of Math
     Oregon State University
     Corva His, Ore gon

                          HOUSEBOAT WASTES

                         I.   INTRODUCTION

      A.,   Authority

      The  Pacific  Northwest Water Laboratory of the Federal Water

 Pollution Control Administration, Northwest Region, was requested

 by the Oregon  State  Sanitary Authority, letter dated January 19,

 1966, to  conduct,

           "A study of  methods and costs of treatment and/or
           disposal of  sewage wastes from houseboats and other
           floating structures."

 The  Federal Water Pollution  Control Act, P,L» 84-660, as amended

 by the Clean Water Restoration Act of 1966, Section 5b, provides

 the  Federal authorization for this study.

     Bo   Purpose and Scope

     The  purpose of  this  study is to develop findings on wastewater

 characteristics,  together with methods and costs of collection and

 treatment  of sewage  wastes from houseboats and other floating

 structures.  The study area  for the report included the States of

Washington, Oregon,  and California with primary emphasis on the

 State of Oregon„

     C.   Problem

     In three Pacific Northwest States, California, Oregon, and

Washington, there are over 1200 houseboats and many other floating

 structures such as boathouses, commercial establishments,  floating

 restaurants, and public restrooms that discharge untreated sewage

wastes directly to waters over which they are moored,,  Few of these

structures have plumbing systems.

     All three states presently have legislation in varying forms,

both local and State, that require houseboats and other floating

structures to treat their sewage before discharge or else require

complete removal to existing shoreside sanitary sewers.

     In California, State law prohibits the discharge, of untreated

sewage to waters of the State and action is being taken by the

California Water Quality Control Board in the form of cease and

desist orders against property owners that have houseboats moored

at their property.  The State has had little success to date in

enforcing these orders.

     In Washington, most houseboats are located in the City of

Seattle and are required by city and county ordinances to connect

to a recently constructed city sewer by June 1967.  Development of

acceptable collection methods and difficulties with local contractors

on construction costs indicate that the June 1967 deadline will not

be met.

     In the State of Oregon, houseboats and other floating structures

will be required specifically by State law (ORS 449.150) to provide

adequate treatment for all wastes discharged to State waters

effective September 1, 1967.  This time limit has recently been

extended by the Sanitary Authority to January 1, 1968, for the

installation of waste treatment facilities for toilet wastes.

Treatment facilities for kitchen, bath, and laundry wastes (not

including garbage or human excreta) were given an extension of

time from September 1, 1967, to January 1, 1971, provided adequate

facilities were installed for toilet wastes and acceptable

progress reports are submitted on January 1, 1969, and January 1,

1970, demonstrating the development of a satisfactory plan

acceptable to the Authority for the disposal of the kitchen,

bath, and laundry wastes.

                       II.  SUMMARY

     Findings  of  this  study on methods  for  the  collection  and  treat-

ment of wastes  from houseboats and other floating  structures are

summarized below:

     1.  The study area  for this report includes the States of

Washington, Oregon, and  California which have over  1200 houseboats

and many other  floating  structures requiring sewage collection

and treatment  facilities.

     2.  With  rare exception, houseboats and other  floating

structures discharge untreated domestic sewage  from toilets,

kitchens, and baths directly to the water in violation of  State

statutes and water quality standards, and this  may  constitute  a

health hazard  to  other water users.

     3.  Average  daily houseboat wastewater quantities are similar

to those for normal land residences with a daily per capita flow

of 75 gpd.  The average  16-hour flow is also similar with  a per

capita flow rate  of 95 gpd.

     4.  The quality of  the houseboat waste is  expected to be

similar to that for a normal land residence.  A separate report

will present data on the quality characteristics of the houseboat


     5.  The collection and treatment of houseboat wastes will be

more expensive than most land-based installations because of their


     6.  Few houseboats have adequate plumbing systems, requiring

major replumbing to collect and treat wastes.  Several methods are

presented for replumbing.  The range of costs are estimated from

$230 to $800 for a single story, one bathroom houseboat.  Plastic

PVC pipe costs the least.  This material is not approved for use

in Oregon or Washington for interior plumbing but is acceptable in


     7.  Central collection of all wastes is recommended wherever

possible requiring that moorages provide central collection

facilities for houseboat wastes and wastewaters from other floating

structures.  Costs for above water, pressure moorage collection

systems installed were estimated to range from 8% to 83 cents per

houseboat per foot of moorage length using cast iron pipe and 5

to 48 cents per houseboat per foot of moorage length using PVC

plastic pipe for moorages ranging in size from 50 to 5 houseboats,

respectively.  Costs would be significantly higher for gravity

underwater collection systems.

     8.  Houseboats located on rivers or waters with a large tidal

fluctuation may require individual pump units to maintain collection

lines above water.  Individual houseboats on these waters may or

may not require pumps depending on whether they treat their wastes

on shore or on the water with a floating facility.  Several pumping

methods have been considered that range in price from $275 to $1500,

not including installation costs.

     9.  Houseboats  located on lakes or other relatively quiet

bodies of water  could use either gravity underwater systems to a

central  lift station or  individual pumping units for pumping

direct to shore.

     10.  Moorages on widely fluctuating rivers may find it

necessary to install lift stations on auxiliary floats to lift

the  waste to shore-based treatment facilities or public sewers.

These units can  be purchased in a price range of $2500 to $7100.

     11.  Recirculating toilets may find application where the w.aste

volume is significant.  This would be the case for intermittent

waste sources that choose to hold the wastes with periodic cleaning

of the holding facilities.

     12.  Pumping all wastes to a shore sewer is the least expensive

and most practical alternative wherever this is possible.   It has

been estimated that exclusive of city or other municipal group

connection charges, a houseboat could pump all wastes to a city

sewer for a cost ranging from $1000 up.

    13.  Individual treatment devices including macerator-chlorinator

toilets,  incinerator toilets,  septic tanks with soil absorption

fields, and aerobic extended aeration units were considered.

    14.  Macerator-chlorinator units presently available commercially

are not recommended for use in treating wastes from the floating

structures considered in this  report.

    15.  Incinerator toilets provide satisfactory treatment  of

toilet wastes  with proper operation and maintenance.   They are

not satisfactory when considering the entire household waste.  The

estimated costs for these units installed will range from $350 to

$575 per unit.

     16.  For no more than one houseboat, a properly designed and

constructed shore septic tank with soil absorption field would provide

satisfactory treatment in areas where soil conditions and local regu-

lations permit.  Such a system installed would cost from $1100 up.

     17.  Aerobic biological treatment units with disinfection

facilities would provide satisfactory treatment of all wastes in

most waters of the study area.  Packaged units are available

commercially that could be used in either a floating- or shore-

type of installation.  Costs for a floating unit would range from

$1800 to treat the wastes from a single houseboat, to $200 per

houseboat for the wastes from 50 houseboats,

     18.  Commercially available biological treatment units are over-

sized for individual houseboat applications making them bulky and

prohibitively expensive.  There is a need for an economical individual

household secondary treatment device capable of operating satisfactorily

with a minimum of operation and maintenance.

     19.  Primary settling with sludge removal facilities and chlori-

nation of the effluent could be considered as an interim method of

treatment.  This process may find application where sewers are not

presently available but are contemplated in the near future.  The

lower degree of treatment will not interfere with other beneficial

uses of the water.  A system adequate to serve up to 25 to 35 house-

boats could be fabricated for $500 to $700, excluding labor costs.


    20.  A system design with three alternatives was made for a

typical, moorage in the Portland, Oregon, area.  The design

considered:  (1) pumping with centrifugal pu;up=i from each house-

boat to a lift station for further lifting to a city sewer,

(2) pumping with centrifugal pumps directly to a city sewer

from each houseboat, and (3) pumping with pneuratic ejectors

to a floating treatment facility.  The cost to r.he individual

houseboat owner for each plan was $935, $1360, and ^1460,

respectively.  The first cost to the moorage owner for each plan

was $7500, $4600,  and $8700, respectively.  These figures do not

include annual costs for financing, operation, and n.aintenance.

                         III.  WASTE CHARACTERISTICS

     Houseboat waste  is  purely domestic in nature and is expected

 to be  similar in both quality and quantity to that of a normal

 land residence.  A  literature search was made to characterize

 the houseboat waste on the basis of normal household character-

 istics but,  the available information is limited particularly on

 an individual household  basis.  That which was found, together with

 field  data collected  to  date, is reported at this time,,

     A.  Waste Quality

     Watson  et al^  '  report on the quality characteristics of

wastewaters  from several individual land residences obtained in

an extensive sampling program of several years.  These data are

expected to be characteristic of houseboat wastes.  Table 1

summarizes data from  this report for three homes.

     B.  Waste Quantity

     The reported average -residential sewage flow per capita is

approximately 75 gallons per day (gpd) with a range from 27 to

200 gpd.(2)(3)  The percent distribution of this flow has been

estimated as follows:

     Waste Source             Reference 2   Reference 3  Average

     Kitchen Wastes              13.3%           6%        107.
     Toilet Wastes               33,4%          41%        38%
     Showers, Washbasins, etc.    33.370          37%        35%
     Laundry Wastes              20.0%           4%        12%

     The  basic design  flow variations  used for small Army

installations are reported on page  13.


                            TABLE 1

             Average Wastewater Quality from Three
                    Homes after Watson(l)
Total Solids
Suspended Solids
Total Volatile Solids
Total Nitrogen
NH3 -Nitrogen
Total P04
Flow (gpd)
Family Characteristics
Total People
Home Laundries
Home 1
Home 2
Home 3

                       Basic Design Flow Variations
                       for Small Army Installations

                 Condition            Per Capita Flow, gpd

                 24-hour average               70
                 16-hour average               37.5
                  4-hour maximum              122.5
                 Extreme Peak                 210

At  this writing, limited data have been obtained on the waste

discharge from houseboats.  Assuming that the waste disposal

pattern would parallel the water consumption with a certain time

lag between usage and discharge and a small consumptive loss,

water use was monitored at several moorages.

     The measured average houseboat per capita water consumption

is  78 gpd, based on the use at two moorages in the City of

Portland (Portland Rowing Club and Water Lane Moorage) and one

moorage in the City of Seattle.  This is based on data for 1585

houseboat-months water use.  With a 5 percent consumptive loss,(l)

the average waste discharge is 74 gallons per capita per day (gpcd)

which agrees closely with figures reported previously.

     Data on hourly flow variations were obtained by installing a

continuous recording device on a water meter serving the Waterly

Lane Moorage located on the Willamette River in Portland, Oregon.

Figure 1 averages these data for two weekend periods.   Analysis

of  the data indicates good agreement with those reported previously.

     Waste quantities from other floating structures can be

estimated from Table 2 reproduced in part from the Manual of Septic

Tank Practice.(2)


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                                     WATER  USE , GALLONS


                           TABLE 2


Type of Establishment

Single family dwellings

Restaurants (toilet & kitchen wastes/patron)

Restaurants (kitchen wastes/meal served)

Public restrooms (toilet wastes only)
Sewage Flow*

  75 gpcd

7-10 gallons

2%-3 gallons

   5 gallons/
Public bathhouses (bathhouse, showers, toilets)    10 gpcd
Stores (per toilet room)
 400 gallons/
*If recirculation toilets are used, the volume of toilet waste
 could be calculated on the basis of four gallons per 80 usages,

                        IV.  PLUMBING REQUIREMENTS

      To  provide  treatment  for wastes from houseboats and other

 floating structures,  the wastes must first be collected and trans-

 ported to a  single point.  In the case of houseboats that treat

 their wastes individually, this point may end at the houseboat.

 For a moorage with a  number of houseboats, boathouses with sanitary

 facilities,  and  other structures with liquid waste discharges, a

 common collection system with a single treatment facility is the

 most  economical  approach.

      The  problem of collection is complicated by flood stage

 fluctuations on  the rivers (as much as 27 feet on the Willamette

 and Columbia Rivers in the vicinity of Portland), river currents,

 floating  and submerged trash, tidal fluctuations, and the fact

 that  few  of  the  existing houseboats and other floating structures

have  plumbing systems.  To overcome these problems, individual

pumping units at each waste source with sufficient capacity to

pump  the waste to a shore-based facility or a facility at the

moorage level were considered.   An alternative to the individual

pumping units would be to retain the waste in a holding tank and

use a portable pump to empty the holding tank periodically.   Gravity

systems could be used on lakes  and other quiet bodies of water but

these were not considered in this report,

     This section is composed of two portions dealing first  with

the individual collection,  holding,  and pumping systems,  and

second with the moorage collection and pumping systems.


     It is expected that the individual will be responsible up to

the point of system connection and the moorage will be responsible

for providing a conveyance system and holding tank emptying facilities,

if necessary.

     A.  Houseboats

     The waste collection may require complete replumbing and indivi-

dual pumping units or simple holding facilities with provision made

for draining periodically.  In areas where gravity systems can be

utilized, replumbing may be all that is required.

     The drainage system of houseboats, boathouses, and other float-

ing structures with few exceptions, is composed of vertical drain

lines from each fixture discharging directly to the water.  Because

all wastes, including kitchen, laundry, and bath, require treatment,

most houseboats will require complete replumbing.  Also, in area's

where necessary to maintain lines above water, each structure will

have to be provided with a pump unit or a holding tank.

          1.  Plumbing Methods

          Methods and materials for plumbing installations on house-

boats and other floating structures must comply with State and/or

local plumbing codes except when alternatives are approved by the

plumbing department with jurisdiction.  It is recognized that there

are structural and financial problems involved unique to the existing

houseboats which may justify relaxation of certain code requirements

to effect a reasonable solution.

          The Floating Homes Association, Seattle, Washington, which

represents about 500 houseboats located on Lake Union within the


 City of Seattle,  together with the  City  of  Seattle  Plumbing Depart-

 ment has developed an acceptable  plan for replumbing  existing

 houseboats.   At this time approximately  80  houseboats have been

 plumbed according to this plan.   This basic plan, modified to

 meet the State of Oregon Plumbing Code,  is  presented  in Figure 2.

          This method of  plumbing  for  houseboats  facilitates

 construction and  minimizes the expense involved, yet  provides

 a completely workable system.   In the future, all houseboats

 without exception will be expected  to comply with State or

 local plumbing codes.

          Approved materials for replumbing  are specified by most

 State or local codes.  In Oregon, the  State plumbing  code requires

 that all fixtures be trapped and  that  waste discharge piping be

 either galvanized steel,  galvanized wrought iron, cast iron, brass,

 lead pipe, or copper tube.  Plastic pipes, Acrylonitrile-Butadiene-

 Styrene  (ABS),  or Polyvinyl Chloride  (PVC), that conform to the

 temporary standards  of the U.  S.  Department of Commerce (CS270-65

 for  ABS  pipe  and  CS  272-65 for PVC pipe) are acceptable for use

 in California  but are  not  approved in  Oregon or Washington.  The

 National  Plumbing Code has proposed revisions to include plastic

 pipe and  fittings  for water, sewer,  drain, and waste lines„  When

 and  if  these  revisions are made, Oregon and Washington,  as well,

 may  allow the  use  of plastic materials.

         To provide relative cost estimates for replumbing house-

 boats, a  typical  floor plan for a one bathroom,  single story

houseboat was chosen and cost estimates were made for replumbing


                                       " IF OVER 4' FROM  ./TUB SHOWER

                                                         IF OVER 4' FROM MAIN WASTE
                                                          INDIRECT WASTE TO SUMP
                                                          EITHER  DOCK  OR INDIVI-
                                                          DUAL HOUSE SUMP,
                        PLAN 3
                                          HOUSEBOAT  PLUMBING  PLANS
                                                      FIGURE  2

with  copper, cast  iron, and plastic materials according to the

plan  illustrated by Figure 2.  The cost of material was based on

an  average  of unit prices at local distributors in the State of

Oregon.  Unit labor costs were estimated at $9.50 per man-hour and

the construction time at 40 man-hours using copper pipe.*  Construc-

tion  time for the other two materials was based on a recent article

by  Pierce using copper material as a reference,(5)  These times are

given as follows?
                     Material              Time	

                     Copper                   1.0
                     Plastic (ABS or PVC)     0.35
                     Cast iron                1.83

The estimated cost for replumbing a one-bathroom single story

houseboat is $230 with plastic materials, $560 with copper

materials, and $800 with cast iron.  These costs are summarized

in Table 3.

         The estimated labor costs in Table 3 can be reduced

significantly if the owner assists in the work as indicated by

three examples of houseboat replumbing presented in Appendix A.

The owners did their own carpenter work and assisted the plumber

which reduced the average construction time by a factor of two.

It should be noted that the construction times for cast iron and

plastic materials are hypothetical and may differ significantly in

*Based on figures provided by University Mechanical Contractors,  Inc.,
 Seattle, Washington, for three houseboats.   See Appendix A for details,


                               TABLE 3


Cast Iron
Plastic (PVC
Cost of
$ 180
$ 110
or ABS) $ 100
Pumping Methods
$ 380
$ 690
$ 130

$ 560
$ 800
$ 230

          Where pump units are required, the houseboat drainage system

should tie into a small sump with a pump or ejector to convey the

waste under pressure to point of treatment or disposal.  The sump

or ejector which could be connected to the houseboat float should

conform to the following design criteria;

               a.  Storage capacity excluding pump of at least 20


               b.  Material should be cast iron, fiberglass,

aluminum, PVC, or steel coated with an asphalt or epoxy compound.

The weight of the sump should not be excessive.

               c,  Maximum liquid level in the sump should be 30

inches below the moorage connection, if possible.

               d.  Inlet diameter should be a minimum of 3 inches

and the outlet diameter a minimum of 2 inches.  If suitable

maceration precedes the pump, the outlet can be reduced even more.

               e.  Adequate venting should be provided.  A 2-inch

vent extended above the roof line is suggested.


                f.   There must be  no overflow  from  the sump.

                g.   It  should be located or protected in such a

 manner as  to  prevent damage from  boats, swimmers,  floating or

 submerged  debris,  and  to facilitate maintenance and inspection.

         In pump selection, there are a number of  alternatives

 open  to the houseboat  owner depending on his  location and whether

 treatment  is  provided  on shore or on the water.

         If the  waste  is treated  on shore, which is recommended

 wherever feasible,  the pump capacity should be 55  gpm at heads

 varying from  10  to  over 40 feet.  An arbitrary selection of 20

 feet was made  to differentiate between high and medium head pumps

 on  the basis  of  several typical head-capacity curves.  The capacity

 of  55  gpm was  selected on the basis of providing a 2.5 feet per

 second (fps) velocity  in a 3-inch pipe.

         High head  pumps would be required for pumping directly

 to  shore in the  Portland, Oregon,  area.  In nearly all other areas

 where  houseboats are located in the States of Oregon, Washington,

 and California, medium head pumps could be used for pumping wastes

 to  shore.

         If the waste is pumped to a floating treatment facility

 or  to an auxiliary  lift station used in place of individual high

head pumps, a low head pump should be used with a capacity of at

 least 55 gpm at a head of 0 to 10 feet.

         Two types of pumps have been considered;   pneumatic

 ejectors and centrifugal pumps.


          Pneumatic ejectors consist essentially of a closed tank

into which sewage flows by gravity until it reaches a certain depth.

Then air under pressure is admitted into the tank to displace the

sewage through the discharge line until the low water level control

cuts off the air supply.  Ejectors require one-way valves on both

inlet and outlet pipes, venting on the inlet side, level control

mechanisms, and a source of air under pressure.  For individual

houseboat pumping, pneumatic ejector units should provide their

own air supply.  If pneumatic systems were standardized on all

houseboats, perhaps moorages would provide the air supply, but this

possibility is unlikely.

          Pneumatic ejectors have the advantage of operating satis-

factorily over a wide range of heads from a minimal to a high head,

and to pass solids equal in size to the inlet and discharge piping.

Their main disadvantages include problems with check valves seating

properly, air control, and their high initial cost.  While they are

not free from operating problems, they are usually superior to centri-

fugal pumps that handle raw sewage.

          Pneumatic ejectors are ideally suited for houseboats in

principle because of their adaptability to various head requirements

and their nonclog characteristics.  However, few commercially

available units are economically feasible for houseboat application.

          At present, an ejector specific for houseboats for pumping

up to heads of about 20 feet is being developed in Portland.  This

work is aimed primarily at developing a unit that is small, self-


contained, that minimizes problems with controls and check valve

clogging on the inlet side, and that has a significantly lower cost.

A test unit has been constructed and will be operated on a

houseboat for several  months to obtain data on its operation.

An approximate cost of this unit exclusive of valves, fittings,

and the small compressor to activate the ejector is $550.  The

additional cost of valves, fittings, etc. and the compressor would

run between $150 and $200 for a total price of approximately $750.

An ejector sufficient to pump against higher heads would be

considerably more expensive--on the order of $1500.

     Radial flow centrifugal pumps, submerged or dry, were

considered as applicable for individual houseboat pumps.  This

type was chosen because it is less expensive than other types of

pumps and is available commercially in packaged sump type


     Centrifugal pumps are compact and less expensive than

pneumatic ejectors.  Their main disadvantages include: (1) operating

head limitations and (2) clogging problems due to rags, stringy

material, and other solids found in raw sewage.

     High head centrifugal pumps are available commercially

and, with minor modification, can satisfactorily pump houseboat

wastes ashore in high head pumping areas.  Modifications include

throttling of the flow to reduce velocities when the total pumping

head requirement is low.  This may also necessitate maceration of

the sewage prior to pumping in order to maintain a system free from


clogging,  It  is estimated  that a high head pump and sump, not.

installed, would cost at  least $450.  With maceration precedio^  the

pump,  the cost  is estimated at $600.

          Low  head centrifugal pumps are also available commercially

and could be used without modification for pumping ashore  in .iteas

with a 10- iv  20-foot head requirement.  A packaged sump and pu>  \-

of this  type is estimated to cost at least $330 not installed

          A. less, expensive  low head centrifugal pump could be us-^sl

for pumping at  the moorage level against heads less than 10 feet

but would require some modifications.  Throttling of the discharge

which may in turn require maceration would be necessary or the static

lift would have to be increased above 3 feet to assure dependable

service.  The cost for this type of pump with sump riot installed

would be at least $275.  To provide adequate maceration prior to

the pump would cost on the order of $150 for a total price of $425.

          A submersible type of centrifugal pump application that

could be used when throttling is required is illustrated schematically

by Figure 3.  This design includes a food grinder on the inlet and

a gate valve on the discharge line for throttling.  The grinder

macerates the sewage solids which reduces pump and valve clogging.

Throttling should be avoided if at all possible since this requires

additional and frequent maintenance.

          The disadvantages to this design should be carefully

considered before actual installation.  These are:

            3" Flexible Pipe
            to Houseboat
 2" Vent
to roof lineN
                                       /O-IO, I0-30psi  Pressure Gage

                                                 ,2" Gate Valve
                                                      Union  ^^—Clamped Connection
                                                           2"Flexible Pipe
                                    2* Discharge Pipe
                                        -See State code for
                                         approved material
       NOTE: inlet, Outlet and Vent pipes require watertight
              Clamped connection can be used as safety
              shear section.
              Food Grinder is optional feature-not
              recommended unless throttling required.
                                                           CENTRIFUGAL  SUMP
                                                                 FIGURE 3

               a.  The use of food grinders on raw sewage has serious

drawbacks, because they were not designed for this type of operation.

Any rags, sanitary napkins, or other long stringy material would

most  likely clog the grinder and require manual cleaning.  The life

of the unit under these conditions is unknown and in most cases

standard warranties would not be applicable.  There is only one

instance reported in the literature of a similar setup using a food

grinder to precede a pump.  Watson et al.    report using a food

grinder in their waste sampling apparatus for several individual

households for several years with no apparent difficulties.

               b.  The grinder would have to be modified by placing

the manual restart switch outside the sump and the motor would have

to be sealed to water tightness.

               c.  A switching mechanism is also required to start

the grinder when there is flow to the sump.

               d.  Few centrifugal pumps in a feasible price range

for houseboat use will pass rags, sanitary napkins, etc. without

clogging.  The use of these pumps requires either close control

over what is discharged to the sewer or frequent maintenance.

          A unit with the grinder option has been constructed and

is being used in a 6-week houseboat sampling program in Seattle,

Washington.  Data on the installation cost and operation of this

unit will be made available in a separate report.

          An alternative to use of a food grinder would be to install

a macerating type pump in the interior plumbing system of the structure.


This  type of pump  is commercially available and is used widely for

draining mobile home holding tanks and other types of sewage hold-

ing  facilities where the pumping head is less than 4 feet.

         This alternative has the advantages over the food grinder

of being a  tried and tested unit and is considerably less expensive.

It is estimated that this unit could be installed for approximately

$100 and would result in additional savings by allowing the use of

plumbing materials no greater than 2 inches.  Figure 4 gives a

schematic layout of this system.

         Table 4 summarizes the various plumbing and pumping methods

with their  associated costs.

     B.  O.ther Floating Structures

     For floating structures other than houseboats, with inter-

mittent, usage, such as boathouses, public restrooms, etc., a

number of commercially available devices could be employed for

the collection and/or treatment of the wastes.

     If the structure has only a toilet such as many of the

public restrooms,  recirculating, chemical,  or incinerator toilets

could be successfuly used.   With the exception of the incinerator

toilet, these methods require facilities for periodical cleaning;

e.g., a portable sewage pump could convey the wastes to a point of

treatment or disposal.

     For structures with waste sources other than toilets such as

certain boathouses, some commercial facilities including floating

restaurants, boat  supply stores,  etc.  with sink and bath or shower


                   METHOD I
                                       i sv.'MW.^ w.j. i ss sRc-g
                                                  Moorage Collection
                                                   Portable Sump
                                      600 Gal Ion
                                      Holding Tank
                     METHOD  E
                                       MACERATING PUMP AND
                                   RECIRCULATING  TOILET APPL.
                                               FIGURE 4

wastes, holding tanks could be used with one of the three toilet

devices mentioned above.  The tanks could be sized to retain the

waste for several weeks or longer on the basis of flow quantities

given previously in Table 2.  Disinfectant chemicals would be

required to inhibit sewage decomposition and offensive odors.

An installation similar to that illustrated by Method II in

Figure 4 could be used.  The estimated cost for holding tanks and

recirculating toilets to accommodate two complete restrooms with

washbasin and shower facilities for a 2-week period would cost

from $700 to $900.

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                        V,   MOORAGE  COLLECTION

      This section of the  report  presents  design criteria and cost

 estimates for a moorage collection system,  including design

 capacity,  swells,  waves,  float connections, effects of  temperature,

 selection of materials, and  design of houseboat connections and

 lift stations.

      A.   Collection  System

      The  first  step  in the planning  of a moorage collection system

 is  the overall  plan  or system layout in which both present and

 future sources  of  waste must be  considered,

      The wastes  on a houseboat moorage or marina come from a

 variety of sources other  than houseboats.  These include boat-

 houses with  sanitary facilities, public restrooms, floating

 restaurants,  snack bars,  commercial establishments with sanitary

 facilities,  and  pleasure  craft with toilets.  Wastes of a

 continuous nature  require individual connections to the moorage

 system.  This includes the houseboats,  floating restaurants and

 snack bars,  and  other commercial establishments with a continuing

water use.   Other  intermittent wastes from public restrooms,  boat-

houses, and  pleasure craft,  and certain of the commercial establish-

ments such as boat supply houses, repair shops, etc.,  may not

require individual, connection to the system but instead, could

utilize holding tanks, recirculating ,  chemical,  or incinerator


     Provisions should be made for any future expansion of the moorage

for houseboat mooring, boathouses, etc.  The systems should be designed

with capacity to receive wastes expected during the life of the moorage.

     Moorages located on rivers, such as nearly all those in the

State of Oregon, will require pressure collection systems to main-

tain lines above water because of river currents, submerged and

floating trash, and water stage fluctuations.  As discussed previously,

each individual connection to the system will require a pump with

adequate capacity to force the waste to a central point for treatment

or further pumping.  This may be on the water or on the shore.

     In the States of Washington and California, most houseboats

are located on lakes, bays, or other relatively calm bodies of

water with little stage fluctuation.  In these situations, gravity

lines under water to a central lift station could be considered as

well as the individual pump units for a pressure system.

          1.  Design Capacity and Sizes

          A sanitary sewer has two main functions:  (1) to carry

the peak discharge for which it is designed, and (2) to transport

suspended solids so that deposits in the sewer are kept to a minimum.

          The system should be designed to provide scouring velocities

greater than 2.5 fps at least two times a day to prevent corrosive

effects and potential clogging from sludge accumulations.

          For moorage pressure systems, the design peak flow will

be dictated by the number of pumps on the system that operate

 simultaneously, the rate of waste flow to the sump,  the pumping

 characteristics,  and the physical layout of the system.  The pipe

 should be sized to pass the peak flow at a velocity  greater than

 2,5 fps but less  than 10 fps,

           The minimum size pipe,  where more than one pump is

 connected,  is 3 inches.  This  size is adequate for peak discharge

 rates up to 220 gpm.   For rates  greater than this, a larger

 diameter pipe is  required.

          Appendix B presents design curves to indicate  number of

 pumps operating simultaneously for 99.9% of the time for multiple

 pump systems  on the basis of number of pumps connected  to the

 system,  rate  of inflow to the  pump sump,  and pump discharge rate.

 For example,  a system with 50  pumps connected,  a waste  discharge

 of  100 gallons in an  hour,  and a  pump discharge rate of 60  gpm

 would have  no more than six pumps  operating simultaneously  for

 99.9% of  the  time.

          2.   Swells,  Waves, and  Float  Connections

          To  allow for unequal movements  of one portion of  the

 moorage walkway relative  to the next,  caused by swells,  waves,  or

 unequal loadings,  lengths  of flexible  pipe  should be used wherever

 one walkway joins another.  This  is  illustrated by Figure 5.

          The  length of flexible pipe  should  allow for  an elevation

difference of 3 to 4 feet between adjoining walkways.  There  should

also be no sags with the additional  length made  up in the form of

a horizontal bend.


                                      FLEXIBLE PIPING
                            MOORAGE  WALKWAY^
                                   WALKWAY CONNECTIONS

           3.   Temperature  Effects

           Provision should be  made  to  prevent  freezing  of  the

 lines  and  to  provide for expansion-contraction.  The  lowest  one-

 day average temperature noted  during 25 years  of record at the

 U.  S.  Weather Bureau Portland  Airport  Station  was  -3  degrees F  on

 February 2, 1950.   The maximum recorded for  this station was

 107 degrees F on July 30,  1950.

           The minimum temperature value should be  used  to  calcu-

 late the amount  of  insulation  necessary.  Flexible connections

 between separate floats as described above will provide sufficient

 allowance  for expansion and contraction if connection of the pipe

 to  the moorage is such that the pipe can move  within  the connection.

           4.   Materials

           The following materials have been  accepted  for use on

 houseboat  moorages  by the  City of Seattle and  would most likely

 be  acceptable in Oregon and California as well:

               a.  Hewitt Robbins Flexible Pipes F55,  F66*

               b.  White National Rubber Flexible Pipes  CH22A,
                  CH64A (Neoprene)*

               c.  Plastic  (PVC) 160# Test (Solvent joint or
                  rubber joint)

               d.  Cast Iron and Ductile Iron

               e.  Copper Class L

               f.  Transite  (Water Pressure Type)
*Mention of products and manufacturers is for identification only
and does not imply endorsement by the Federal Water Pollution
Control Administration or the U.S. Department of the Interior.


Cost of material, labor for installation, and expected life will all

vary considerabl}1 for these materials.  Generally, plastic and cast

iron are the cheaper with flexible pipes the more expensive.  Concern-

ing labor costs, flexible and plastic pipes would be cheapest with

cast iron the most expensive; however, cast iron, pipe is the most

durable with plastic possibly the least.

          The specific situation, which will vary considerably from

moorage to moorage, will dictate the most economical choice of

material.  However, as a rough guide for estimating the cost of

moorage collection systems installed, Figure 6 indicates the cost

per houseboat per foot of moorage length for plastic and cast iron

materials.  An example on use of Figure 6 is given later in the


          5=  Houseboat Connection

          A standard form of connection should be adopted by all

morrages because of the mobility of the houseboats.  It is suggested

that where above water pressure systems are required, a standard

3"x3" 2-inch Tee or Wye with a 2-inch check valve be provided for

each waste connection,,  A 2-inch stub from the check valve should

be provided for a clamped flexible pipe connection to the houseboat

sump.  The clamped connection can be designed to provide a point

of failure in the event the houseboat breaks loose from its mooring.

          A minimum grade of 0.25 inch per foot should be maintained

between the check valve and the 90 degree elbow on the discharge pipe

of the sump with no sags or low spots in the connection.  This method













         PVC PLASTIC
             10     20     30

          NO. Of HOUSftOATS
                              MOORAGE COLLECTION  COSTS
                                          FIGURE 6

of connection is illustrated by Figure 7 for a centrifugal-type

sump.  The same type of connection could be utilized for a pneumatic


     B.  Moorage Lift Stations

     Central lift stations may be used in lieu of high head individual

pumps at moorages that treat their wastes on shore in areas with

water stage fluctuations greater than about 20 feet.  If treatment

is provided on the water or where water stage fluctuations are not

as severe with maximum ranges between 10 and 20 feet, it will be

possible to pump directly from the houseboat sump to a treatment

facility or public sewer.

     The following design criteria for moorage lift stations are

suggested regarding location, construction, pump capacity, wetwell

design, and estimated costs.  An illustration of a typical installation

is also presented.

          1.  Construction

          The station should be located near the shore ramp to mini-

mize piping and to be convenient for maintenance, operation, and

electrical service.   It should be firmly secured to the moorage

walkway to reduce damage from float movement and be completely

above water.

          Figure 8 suggests a plan which would be applicable at

most moorages.  The station is supported by an auxiliary float and

connected to the houseboat line and shore discharge line with flexible

pipe.  The shore discharge line could be a tubular hand rail along

the ramp.


          Moorage Walkwoy
Shore  Ramp
     3" Pipe
                                         //  Flexible Pipe
                                         /    3"-C.J,Wye

                                         ^Flexible  Connection
Wet Well
                   SECTION  A-A
                                         MOORAGE  LIFT  STATION
                                                FIGURE 8

         PUMP  SWITCH
                         OATE VALVE
                            CLAMPED CONNECTION

                          SHEAR CONNECTION
                                            2" FLEXIBLE HOSE
                                              2"r«ECK VALVE
                                         3? MAIN WYE CONNECTOR
                                             MOORAGE WALKWAY
                               SUMP PUMP
                                    VARABLE DISTANCE  L FT.
                           Vent to
                                            CENTRIFUGAL   SUMP
                                            PUMP INSTALLATION

          Note  that  the  inlet  to  the wetwell  for the illustrated

 station  is approximately 6  feet above the houseboat discharge main

 and  8^ feet above  the maximum  water level in  the houseboat sump.

 With this static head, little  or  no throttling of the sump pump

 would be required.   The  float  should be sufficiently large to

 support  the weight of the station and provide stability against.


          2.  Capacity

          The minimum size  discharge line from the pumps is 2 inches

 for  a macerated or ground sewage  and 3 inches for a raw sewage.

 Since the velocity of flow  in  the discharge pipe should be main-

 tained between 2.5 and 10 fps, it follows that the pump capacity

 for  a 2-inch discharge line should be at least 25 gpm at low river

 stage and a maximum  of 98 gpm  at  minimum head or high river stage.

 For  a 3-inch line the minimum  is  55 and maximum 220 gpm.

          Centrifugal pumps should be able to pass the maximum size

 solids expected for  the  system or severe clogging will result.  For

 a raw uncomminuted sewage they should have a 3-inch solids handling

 capacity.  However,  solids would  not be, a major consideration and

 a less expensive pump could be used if the grinder, sump-pump

 combination, or toilets with macerator pumps are used.

          3.  Wetwell Design

          Design criteria for construction of wetwelLs  are available

 in a number of documents  and are  specified in state regulations.

Essentially the only variable  is  the volume and this is considered


          The selection of proper storage capacity is critical

because it affects the time the sewage is retained in the station

and the frequency of operation of the pumping equipment.  ASCE

Design Manual No. 37^ ' suggests a wetwell size that, with any

combination of inflow and pumping, the cycle of operation for each

pump will not be less than 5 minutes and the maximum detention time

in the wetwell will not exceed 30 minutes.  Based on these criteria,

a pump capacity of 75 to 125 gpm, and a rate of inflow varying from

200 to 900 gpd per houseboat, the following volumes are suggested

for the lift station wetwell serving houseboats.

             No. of                    Capacity
           Houseboats             Wetwell Storage, Gal.

                 1                         20
                 2                         30
               3-7                         50
              8-15                        100
             16-30                        150

The above figures are for total storage which is composed of the

volume between high and low water levels, the dead storage or

storage below low water, and freeboard volume.

          4.  Materials

          The moorage owner has three alternatives in providing a

lift station.  He can purchase the components and fabricate the unit

himself, have it built, or he can purchase a small package lift  •

station ready for installation*  Possibly with exception of the

small moorages, the prefabricated package unit would be the most

practical approach.

          There are a number of package units on the market for

both centrifugal and pneumatic systems that would find application

as moorage lift stations.  The prices vary significantly depending

on the specific application, equipment needed, and manufacturer

with an estimated price range from $2.500 to $7000»  Again, this

is based on pumping uncomminuted sewage„  If the waste is

comminuted or solids removed by an incinerator toilet or other

means, this price range could be reduced,

          Additional details can be obtained directly from the

manufacturers or their representatives regarding specific


                       VI.  TREATMENT

     Wastes from all sources can be treated individually or on a

group basis.  With few exceptions it will be more economical to

treat on a group basis.

     Since most floating structures can travel through and/or

reside on various classes of water, a minimum of secondary treat-

ment or connection to a shore sewer is preferable and is generally

required.  Connection to shore sewers, wherevfer possible, should

be required to consolidate waste treatment responsibility and

regulatory control.

     The remainder of this section discusses available treatment

methods and estimated costs on both an individual and group basis.

     A.  Individual Methods

     Individual treatment should be considered only when the source

is isolated and would cause great expense to connect to a central


          1.  Macerator-Disinfecter Toilets

          This method, as the name implies, macerates and disinfects

the toilet waste before discharge.  Operation of the macerator and

addition of the disinfectant solution are generally automatically

triggered by the flushing action of the toilet.  These toilets

can be either marine or standard type.

          They have been shown''' to effectively reduce coliform

concentrations and provide some measure of organic removals when


operated properly.  There is sone question, at present unanswered,

as to the bacterial efficiency of these units due to the presence

of sewage solids.

          The average cost of these units, based on prices quoted

from three different manufacturers, is approximately $100.  Assuming

an installation cost of $50, the total installed cost would be on

the order of $150.

          Macerator-disinfecter units have several disadvantages:

               a.  They do not provide secondary treatment.

               b.  These units are difficult to police to insure

adequate operation and maintenance.

               c.  Use on board government vessels has demonstrated

short life and periodic equipment repairs and replacement.

               d.  They do not significantly reduce solids concen-

trations nor provide a reduction in the degradable organic matter,

and the bactericidal efficiency is questionable, and generally,


               e.  Treatment is provided only for toilet wastes.

          These units have received approval in a number of states

for use on pleasure craft.  However, for reasons mentioned above,

they are not recommended for use in the houseboat problem.

          2.  Incinerator Toilets

          These units provide complete gas incineration of toilet

wastes to an inert ash.  They use no water for flushing but can


handle  up  to  a  quart  of  liquid material.  The  combustion time  is

 from 14 to 18 minutes, but  the combustion cycle  can be  interrupted

 at  any  point  for  subsequent usage of  the unit.   Combustion vapors

 are vented to the atmosphere.  Operation is completely  automatic

 and the toilet  becomes nonusable when it is not  functioning

properly.   They use natural or LP gas  and are  ignited by 110 volts

AC  or a 12-volt DC battery.

           The treatment  efficiency of  these units  is complete  with

 100 percent removal of the sanitary waste.  Like the macerator-

disinfecter toilet, though, they provide treatment only for the

toilet  wastes or  based on figures presented previously, only

33  percent of the total  waste volume.  Table 5 indicates the

percent of the  total  household waste represented by the toilet

wastes.  This also would represent the percent efficiency of the

incinerator toilets in removal of these parameters.  This varies

from a  low of 23  percent total phosphate removal to a high of  100

percent NH^-nitrogen  removal.  While  this comparison is at best

a gross  one,  it does  indicate that incinerator toilets do not

provide  adequate  treatment on a total household waste basis when

secondary  treatment is the desired standard.

          The first cost of these units, not installed, runs from

$300 to  $500 depending on the type purchased and the extra features

desired.  There would also be the cost for gas and electricity but

these operating costs are minimal.   Installation of these units

could be estimated at approximately $50 to $75.


                                  TABLE 5

          Comparison of Faces and Urine Waste Quantities to Total
                 Household Wastes for a Family of 5 People
 Urine & Feces
Contribution (8)
Total Household
Contribution (1)
Urine & Feces
  of Total
Total Nitrogen
Total P04
Grease or Total
Total Solids
Fat 22
          The primary advantages of these devices include:  (1) com-

plete removal of fecal and urine wastes, and elimination of most of

the public health hazard from houseboat wastes; (2) low first cost

and operation costs; (3) easy installation and maintenance, and

(4) assured quality control if properly installed since there is

no place for the waste to go if the unit is not operating.  Adequate

maintenance and operation are essential.

          The primary disadvantages of the units, and it should be

noted that these are undocumented, include:  (1) odor problems,

(2) questionable durability under continued long-term usage, and

(3) less than secondary treatment is provided  for the total household

waste.  Also, a relatively high cost is involved considering the

degree of treatment provided.


          It is expected that these units may find application on

facilities with only toilet wastes such as certain boathouses, *

public restrooms, and certain commercial establishments or they

may be used for interim treatment.

          3.  Individual Aerobic Treatment: with Disinfection

          This method consists essentially of a tank with 24 hours

retention time, artificial aeration, solids settling and return,

and chlorination of the effluent before discharge.  It is a simple

system in principle but like any biological system, sensitive to

proper operation.

          There is only one unit presently known .£0 be on the

market suitable for individual application.  This  varies in size

from 750 gpd to 1,250 gpd.

          The efficiency of this unit with proper^installation and

maintenance is on the order of 75 to 85 percent organic removal and

would be acceptable as secondary treatment.

          For the individual houseboat the smallest unit is actually

oversized,  providing 750-gpd capacity when 200 to  400 gpd would be

sufficient.   This would not impair its efficiency  but does suggest

the need for a smaller sized unit.

          The cost of a 750-gpd unit is approximately $1000 delivered

to Portland,  Oregon.   To this would be added cost  of chlorinator,

flotation,  corrosion protection,  and installation  estimated at

$800,  and the total cost would be on the order of  $1800.


          Operation and maintenance of the unit relative to non-

biological forms of treatment are considerably greater both from a

time and money standpoint.

          4.  Shore Treatment

          If the wastewater from the individual houseboat is pumped

to shore for treatment, there are two alternatives.  These include

connection to a public sewer or to a septic tank with absorption

field, provided soil conditions permit.  Other methods such as hold-

ing tanks and extended aeration units are cheaper to use on the


          Each of these alternatives has been investigated and it

appears that the most practical is to pump the wastes to a public

sewer.  This would cost approximately $800 to $1000.  If no public

sewer is available, the next approach would be to pump the wastes to

a septic tank with absorption field or seepage pit on shore.  The

area required for the field or pit can be determined from Table 6.

It is estimated that a system such as this would cost on the order

of $1100, installed.  If land is unavailable or if soil characteristics

do not permit the use of an absorption field, an extended aeration

type plant would be necessary for treatment on the water (a shore-

based facility would be more expensive than providing a floating unit).

     B.  Group Methods

     In instances where connection to a public sewer cannot be made,

moorages and houseboat owners will have to provide their own treatment,

The alternative process discussed here meet State requirements.

They include a floating or shore-based extended aeration unit or

a settling unit with chlorination to be replaced by sewer connection

or secondary process at some designated date in the future.  Each

of these methods with illustrated applications is presented.

                           TABLE 6

    Soil Absorption Areas Required for Single Houseboats
             for Various Percolation Rates(l)
1 or less
30 W
Absorption Area'^)
Using Recirculating
Toilet, ft.
Absorption Area'^)
For Total Houseboat Waste

(1)  Table based on allowable sewage loadings presented in Manual of
     Septic Tank Practice, U.S.P.H.S., No. 562, 1957.

(2)  Based on flow of 100 gpd per houseboat

(3)  Based on flow of 225 gpd per houseboat

(4)  Not suitable for seepage pit

          !„  Extended Aeration

          Packaged extended aeration units are available from a

number of manufacturers in a size range suitable for a moorage

treatment system.  Information on facilities which can be modified

at a reasonable cost for flotation if desired, can best be obtained

through direct contact with a manufacturer.

          Figure 9 illustrates the estimated installed costs of a

floating extended aeration treatment facility for various sized

moorages on a per houseboat basis.  The cost per houseboat decreases

significantly as the size of moorage or number of houseboats served

increases.  For example, the cost per houseboat for serving one

houseboat is $1800 while the cost per houseboat for serving 50

houseboats is $200.  This curve is based on typical prices for a

floating treatment facility.  The cost for a unit installed on shore

would be less and would be recommended in areas with pumping heads

on the order of 10 to 20 feet.  In high head areas such as the

Portland, Oregon, area, it would be more economical to float the

treatment facility with the moorage.

          The major disadvantage to the packaged extended aeration

unit is the degree of competence required for efficient operation.

Like any biological system it is sensitive to a number of parameters

and unless these are understood by the operator, changes can upset

the balance in operation considerably„  Also, the annual costs of

operation are high due to power requirements, and maintenance labor.

    ! 1,506

                        FIRST COST INSTALLED WITH
                        CHLORINATION AND FLOTATION
               10     20      30      40
                                  EXTENDED AERATION
                                 TREATMENT COSTS
                                             FIGURE 9

          If these units are used, it is recommended that a service

agreement from the manufacturer or other reputable servicing firm

be obtained.

          Figures 10 and 11 illustrate typical examples of how and

where floating extended aeration facilities could be used.

          2.  Settling Tank and Chlorination

          This method of treatment will not provide the degree of

efficiency normally required but might be adequate as the first

step in a stage treatment scheme which would lead to secondary


          For the raw houseboat waste, the process would include a

settling tank constructed with a sludge draw off standpipe.  The

effluent would be chlorinated before discharge.

          The settling tank should be designed on the basis of less

than 600 gpd/ft  of surface area and provide a minimum of 2 hours

retention of the design flow.  The design flow should be the 16-hour

daily average or 95 gpcd.  The bottom of the tank should be sloped

at least 2:1 to the sludge draw off pit, and the chlorine contact

chamber should provide a 15 minute contact time on the basis of the

design flow.  If recirculating or incineration toilets are used on

the houseboats, the design flow can be reduced to 70 gpcd and if no

laundry facilities are permitted it can be further reduced to 50 gpcd.

          Figure 12 illustrates a typical design which utilizes a

500 gallon septic tank modified as shown, a 55-gallon barrel with

portable chlorinator, all supported by a wood float over styrofoam



K- S
z <
< u
_i o
U. U


             SCUM .BAFFLE
                                   2 DISCHARGE
                        SETTLING  TANK ft
                    CHLORINATION  TREATMENT

cylinders.  All metal surfaces would be covered with an asphalt,

epoxy, or other approved coating.  This design uses standard,  off-

the-shelf equipment and could be fabricated, excluding labor,  for

approximately $500 to $700.  It would be sufficient in size to

handle up to 35 houseboats using recirculating toilets.  Without

recirculating toilets, 25 houseboats could be connected.  This

unit could later be salvaged for use in construction of a lift

station when sewers become available.  The use of plastic or

fiberglass materials for the settling tank and contact chamber

could be weight saving.  The cost of this material would be some-

what higher but this may be off-set by savings in float requirements

and installation time.

                     VII.  EXAMPLE DESIGN

     The  following  design is  presented  to  illustrate method  of

design, equipment application,  alternatives  for  treatment, and

cost estimates.  It should be emphasized that  these costs  are

only estimates  and  could change significantly  with different

equipment  and labor costs.

    In  the design of this system, three alternatives are


          1.  Centrifugal pumps  at each houseboat  that pump to a

central lift station on the moorage which  in turn lifts the

waste to a Portland city sewer.

         2.  Centrifugal pumps  at each houseboat  with capacity

to pump directly to shore to  a  Portland city sewer.

         3.  Pneumatic ejectors  at each houseboat that pump  to

a floating package  plant.

    Each alternative  is discussed below.   The  basic scheme for

the system design in  plan and profile is shown on Figure 13.

    A.  Basic Design  Criteria

    The moorage is  assumed to accommodate  18 houseboats with no

future expansion considered.    A total of  35 people live on  the


    The average 24-hour flow  is  75 gpcd, and the  average 16-hour

flow is 95 gpcd.  The maximum rate of waste flow  expected from a

houseboat is 50 gallons in an hour.

                                                            PORTLAND CITY SEWER
                                                            MANHOLE SMH INV EL 31.9-
MAX WS EL. 26.8

MIN.Wt EL.0.0
                              4"FORCE MAIN, ATTACHED TO
                                MOORAQE WALKWAY
                                                        NOTE: ELEVATIONS ON DATUM  1.95FT. ABOVE
                                                             M.S.Li  PIPING LAVED  LENGTHS
                                                             BASED  ON  AERIAL PHOTOS »ELEV.
                                 EXISTING PORTLAND CITY
                                 SEWER-MH. S.E.I84
                                   AIR  LINE X

                        FLEXIBLE CONNECTION
                        COLLECTION MAIN
                                                                 BAFFLE BOX
                                                   FLOATING LIFT STATION OR(CENTRIFUGAL OR
                                                   PNEUMATlOFLOATING PACKAGE TREATMENT
             WILLAMETTE  RIVER
              SYSTEM DESIGN
                                                                     FIGURE 13

      The average organic loading per person is CL25 pound of 5-

 da.y biochemical  oxygen demand (BOD)  per  day on the basis of data

 presented in Table I.,

      A minimum velocity of 2 ,,5 fps and a maximum velocity of 10

 fps will, be used to size the force mains.

      A wetwell capacity of 1.50 gallons will  be used as  indicated
      B.   Layout and Cost. Estimates

      Each of the three alternatives  is  discussed  in two  schedules

 on the basis of financial responsibility—that  of the  houseboat

 owner and that  of the  moorage  owner.  Cost  estimates are given for

 each  alternative,

           1 ,  Alternate A

           This  alternate calls  for houseboat  plumbing, centrifugal

 pumps at  each houseboat,  a moorage collection system,  a  lift  station,

 and a discharge force  main with baffle  box  for  connection to  a city

 sewer „

                a0   Schedule_l

                This  schedule is composed of plumbing,  provision of

houseboat  pump  units,  and connection to the moorage system.   It

will be the  responsibility of the houseboat owner.

                Houseboats were assumed  to be plumbed with  copper

materials by a  licensed plumber in accordance with  the plan presented

by Figure 2,

               Packaged submersible centrifugal pumps in 18"x30"

cast iron sumps were used at each houseboat and attached in a manner

similar to that illustrated by Figure 3.

               The grinder mechanism for macerating sewage solids

was not considered necessary as the total lift between the high

water level in the sump and the discharge point to the wetwell was

in excess of 5 feet which is the minimum operating head for the pump.

               The normal operating range of the houseboat pumps

would vary, depending on the number of pumps operating simultaneously,

from 110 to 90 gpm.  The corresponding maximum flow in the collection

system which may be exceeded 0.1 percent of the time, would be 270 gpm.

               Each houseboat pump unit will be connected to the

moorage system with a length of 2-inch flexible hose of a type

mentioned previously.  The hose will be clamped on both ends with

sufficient strength to hold under normal stresses but such that it

will fail first in the event the houseboat breaks from its mooring.

               Estimated costs for plumbing and the pump units are

based on figures reported previously, plumbing at $560 per houseboat

and the pump units including installation at $325 per houseboat.

The cost for making the moorage connection is estimated at $50 per

houseboat.  The total first cost then to each houseboat owner would

be $935.

               b.  Schedule 2

               This schedule includes the moorage collection system,

the lift station, and the shore discharge line with baffle box.  It


would be  the  responsibility  of  the moorage owner  to provide  this


                The moorage collection  systeir  to the wetwell  of  the

lift  station  was  designed of 3-inch Schedule  ^.0 PVC pipe.  This

size  pipe requires an average flow of  55  gpn?  and  is adequate, for

flows up  to 240 gpm«   The peak  flow would actually be 270  gpm but

the difference  was not considered significant enough to warrant

the. use of 4-inch pipe.  The line, is supported at 5 foot intervals

with  devices  that allow  the  pipe to contract  and  expand»   A.  5-foot

long,  3-inch  flexible hose connection  was made every 100 feet and/or

at every  walkway  division,   A standard connection with 3"x3"x2"

tees  and  a 2-inch check valve was provided for every houseboat.

Insulation of the pipe was not  considered necessary on the basis

of heat transfer  calculations for extreme temperatures.  The

weight of the collection system is less than  2 pounds per  foot and

no additional flotation was  considered necessary.

               A  package lift station built in accordance  with

State  requirements was selected with dual nonclog sewage pumps.

To reduce  head  loss and pump  capacity, a. 4-inch .PVC Schedule  40

discharge  line was used.  Pumps with a capacity of 100 gpm at a

head  of 50 feet were  satisfactory for use in the  lift station,,

               It was calculated that the station would support

itself with no additional buoyancy at a depth of 3.5 feet when

empty.  The auxiliary float was designed only to support the

weight of sewage  in the wetwell before pumping and the, weight of


two men.  The float will also give the station stability against


               The force main from the lift station to the shore

sewer is of 4-inch Schedule 40 FVC pipe,,  The shore connection is

similar to that indicated by Figure 8 with a 5-foot length of 4-

inch flexible hose connecting the lift station to 4-inch PVC pipe

attached to the. 60-foot, long ramp,  A 10-foot length of 4-inch

flexible hose is used to connect the shore side of the ramp to the

4-inch PVC main on shore.  The line on shore is laid in trench and

backfilled.  A baffle box is used to dissipate the velocity head

before discharge to the sewer manhole.

               The estimated cost of the moorage collection system

is based on data presented in Figure 6 for the PVC system.  This

cost, for 18 houseboats, is $0,138 per houseboat per foot of

moorage length.  For the example moorage with a total length of

680 feet to the lift station the cost would be $1700.

               The lift station cost with auxiliary float is

estimated at $3600 installed.  This cost is based on typical

material and labor costs for the Portland, Oregon, area.

               The discharge force main of 4-inch PVC Schedule 40

pipe with an energy dissipating baffle box is estimated to cost

$1500 for materials and $700 for labor for a total cost of $2200.

               The total cost to the moorage owner for Alternate A

is $7500.

           2 „  Alternate B

           This alternate calls  for individual, centrifugal pumps

at each houseboat with capacity to pump directly through a moorage

system to  a shore sewer,

               a „  Scheduj,e_j_

               Under  this schedule are the houseboat plumbing and

the  individual, pump units,

               Plumbing would be the same as discussed previously

and  the estimated cost would be $560 per houseboat.

               Each pump unit to pump ashore will require capacity

to pump against a 51,9 foot head plus system losses.  To minimize

head losses and reduce the pump size, a 4-inch collection system

is required,  With a 4-inch collection system and discharge main,

a 1-hp pump with a capacity of 100 gpm at a head of 50 feet can

be used.  Each unit would be connected as discussed previously.

               The estimated cost for each pump unit is $950,

installed, plus an additional $50 for the moorage connection.

The total cost for each houseboat would be $1560 for this alternate.

               bo  Schedule 2

               This schedule would be the same as that discussed

under Schedule 1 with the exception that a lift station would not

be required and a 4-inch collection system would be required rather

than a 3-inch system,   The total estimated cost to the moorage

owner for this schedule would be $4600,  installed.


          3.  Alternate C

           This alternate calls for pneumatic ejectors at each house-

boat  that pump to a central floating treatment plant.

               a.  Schedule 1

               Plumbing is the same as discussed earlier with an

estimated cost of $560 per houseboat.

               The pneumatic ejector units are complete packaged

units sized for an individual household.  The total pumping head is

less  than 10 feet and a low pressure ejector is utilized.  The

estimated cost for the ejector is $800 installed.  There would be

an additional charge of $50 for the connection to the moorage system.

               The total cost to the houseboat owner for this schedule

is $1410.

               b.  Schedule 2

               For this alternate the moorage owner would have to

provide a moorage collection system and a floating treatment facility.

               The moorage collection system would be the same as

that discussed under Schedule 2, Alternate A, with an estimated

cost of $1700.

               The cost for the floating treatment facility was

estimated on the basis of data provided in Figure 9.  This estimates

a cost of $7000 or $390 per houseboat.

               The total cost to the moorage owner for Alternate C

is $8700.

          4.  Summary

          Costs for the three alternatives are summarized in Table 7.


Alternate A  is  the  least expensive method for the houseboat owner

but  involves a  greater cost for the moorage owner.  Centrifugal

pumps,  with  their inherent difficulties in pumping raw sewage

are  also a disadvantage,  Alternate B is the least expensive for

the  moorage  owner but the most expensive for the houseboat owner.

It also involves the use of centrifugal pumps for raw sewage and

large expensive pump installations at each houseboat.  Alternate C

is expensive for both the houseboat owners and the. moorage owners.

Pneumatic ejectors, though, would provide dependable none log

service and possibly in the long run be more economical.

         The floating treatment facility on the other hand may

prove to be much more expensive than the first cost indicates

because of annual operation and maintenance, costs.

         It should also be remembered that the costs presented in

Table 7 do not represent annual costs but simply the first cost

for  capital investment.  Annual operation, maintenance, replacement,

and  financing costs may present an entirely different outlook and

should  be considered before deciding on any one method.

                              TABLE 1

                           COST SUMMARY

Schedule                 Alternate A    Alternate B    Alternate C

1--Houseboat Cost
    Plumbing               $  560         $  560         $  560
    Sump,  pump & connection   375           1000            850
   TOTAL COSTS             $  935         $ 1560         $ 1410

2--Moorage Cost
    Collection System      $ 1700         $ 2400         $ 1700
    Lift Station             3600
    Force  Main & Baffle Box  2200           2200
    Floating Treatment        	-           	-           7000
   TOTAL COSTS             $ 7500         $ 4600         $ 8700


                         VIII.  BIBLIOGRAPHY
  1.  Watson,  K. S., Farrell, R. P,, and Anderson, J. S „  "The
          Contribution  from the Individual Home to the Sewer
          System."  Paper presented before annual WPCF Meeting,
          September 1966,,
  2.  Manual of Septic Tank Practices.  Public Health Service
          Publication No. 526, 1957.
 3.   "The Effect of Industrial Wastes on Sewage Treatment."  New
          England Interstate Water Pollution Control Commission,
          June 1965.
 4.  Babbitt, R. E.  Sewerage and Sewerage Treatment.,  6th ed.
          John Wiley and Sons, Inc., 1949„

 5.  Pierce, J. W.  "Plastic Pipe—A Progress Report/1  Civil
          Engineering, ASCE, February 1967.
 6.  Design and Construction of Sanitary and Stcjrm Sewers.  ASCE
          Manual of Practice No. 37, 1960.
 7.  "Evaluation of Marine Toilet Chlorinator Units."  by Syracuse
          University Research Corporation for New York State
          Health Department.  Report No, 9, May 1962.

 8.  Sunderman, F. W. and Bociner, F.  "Nutritional Values in
          Clinical Medicine." p. 260.  W. B, Saunders and Co,,

 9.  Personal communication with Dr. Donald Guthrie, Associate
          Professor of Mathematics at Oregon State University,
          Corvallis, Oregon.
10.  Cox,  D.  R.  and Smith,  W.  L.   Queues.   John Wiley and Sons,
          Inc.,  1961.


              APPENDIX A

Plumbing Costs for Three Houseboats in
          Seattle, Washington


                    iaiTVWAVN.fi • 9. O. • O X •• • PMQMC

                     • CATTLE, WABHINOTON 9B1OB
        Terry Pattut
        2039 Falrvlaw Ave. East
        Saa-HU. Washington 98102
   CAIN Upon COWUTIM «r w«««
                                            f. a. NO.
        2339 PalrvlM Ay*, b.
        Rorough waitat, vwitt and watar for houcaboat
                   9/14   9/21


                           CO NTHACTORS
                     BCATTLE. WASH INOTON 9B1OS
                                                 October 11,
       Dan Brackett
      .2818 Boyer East
       Seattle, Washington
Timid C««H UMK coupumoM OF wonn 0ur JOB NO. |9|9
Rcrough wastes, vonts and »at«r for hous* boat
Kattleman 16 7.30 131.40
Porni It

Overhead I5£

Foe 10*

Sales Tax

P. O. NO.



                    • CATTLE, WA1MINOTON ••IDS
KH.OTO .  281 A Boynr Avenue Ea§t
       Seattle, Washington 96108
                                          DAT. October  7
'. • run* C*«H un» eemunm or won Our
Rough In
Kettleman 7
Petereon 7

MB NO. 2047

U 84 7.30
II 6* 7.30

Overhead 15*

Fee 10*

Sales Tax
9. O. MO.


        APPENDIX B

Design Curves for Multiple
       Pump Systems


     Moorage collection systems with a number of pumps connected
in parallel should have adequate capacity for the maximum probable
number of pumps operating simultaneously.  To determine the
probable maximum number for various size moorages, queuing theory
was employed to relate pertinent design parameters which include:
          1.  Number of pumps connected to system.
          2.  System head characteristics.
          3.  Rate of sewage inflow.
          4.  Pump head-capacity characteristics.
          5.  Rate of pumping.
     A relationship developed by Guthrie^'and Cox'  ' for
indicating the proportion of time or probability that any number
of pumps in various sized systems operate simultaneously is given
by equation 1.
                Pj - P0rj     (D

                rj • 1 for j»o
                                         ™  JJ for 1*- j *N  (3)
                     (       j!          (o)  )
             N = number of pumps connected to the system
             I • rate of inflow to the pump sump, gallons per minutes (gpm)
             0 - pumping rate, gpm

          Pj * proportion of time or probability that j pumps are

in operation where j varies fron o  N

     For general use a family of curves was prepared for Pj by vary-

ing the number of pumps connected to the system from 0 to 50, the

rate of inflow from 50 gallons per hour (gph) to 200 gph and the

pumping rate from 120 to 30 gpm,  These curves are given in Figures

14 and 15.  The indicated number of pumps operating simultaneously

would cover over 99.9 percent of the time; i.e., there would be a

0.1 percent chance that the indicated number of pumps operating

would be exceeded.

     It should be remembered when using the curves that the average

24-hour houseboat waste flow is less than 200 gallons and the

average pumping rate would be on the order of 60 to 100 gpm.

                     INFLOW RATE -   50 GPH
I  i
                  10   15    20   25   30   35   40
                       Number of Pumps Connected to System
                                              45   50
                     INFLOW RATE =   100 GPH
Q- -3
                     INFLOW  RATE *   150 GPH